1.
Orbital elements
–
Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are considered in classical two-body systems. There are many different ways to describe the same orbit. A real orbit changes over time due to perturbations by other objects. A Keplerian orbit is merely an idealized, mathematical approximation at a particular time, the traditional orbital elements are the six Keplerian elements, after Johannes Kepler and his laws of planetary motion. When viewed from a frame, two orbiting bodies trace out distinct trajectories. Each of these trajectories has its focus at the center of mass. When viewed from a non-inertial frame centred on one of the bodies, only the trajectory of the body is apparent. An orbit has two sets of Keplerian elements depending on which body is used as the point of reference, the reference body is called the primary, the other body is called the secondary. The primary does not necessarily possess more mass than the secondary, and even when the bodies are of equal mass, the orbital elements depend on the choice of the primary. The main two elements that define the shape and size of the ellipse, Eccentricity —shape of the ellipse, semimajor axis —the sum of the periapsis and apoapsis distances divided by two. For circular orbits, the axis is the distance between the centers of the bodies, not the distance of the bodies from the center of mass. For paraboles or hyperboles, this is infinite, tilt angle is measured perpendicular to line of intersection between orbital plane and reference plane. Any three points on an ellipse will define the ellipse orbital plane, the plane and the ellipse are both two-dimensional objects defined in three-dimensional space. Longitude of the ascending node —horizontally orients the ascending node of the ellipse with respect to the reference frames vernal point, and finally, Argument of periapsis defines the orientation of the ellipse in the orbital plane, as an angle measured from the ascending node to the periapsis. True anomaly at epoch defines the position of the body along the ellipse at a specific time. The mean anomaly is a mathematically convenient angle which varies linearly with time and it can be converted into the true anomaly ν, which does represent the real geometric angle in the plane of the ellipse, between periapsis and the position of the orbiting object at any given time. Thus, the anomaly is shown as the red angle ν in the diagram
Orbital elements
–
In this diagram, the
orbital plane (yellow) intersects a reference plane (gray). For earth-orbiting satellites, the reference plane is usually the Earth's equatorial plane, and for satellites in solar orbits it is the
ecliptic plane. The intersection is called the
line of nodes, as it connects the center of mass with the ascending and descending nodes. This plane, together with the
Vernal Point (♈), establishes a reference frame.
2.
NASA
–
President Dwight D. Eisenhower established NASA in 1958 with a distinctly civilian orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29,1958, disestablishing NASAs predecessor, the new agency became operational on October 1,1958. Since that time, most US space exploration efforts have led by NASA, including the Apollo Moon landing missions, the Skylab space station. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the agency is also responsible for the Launch Services Program which provides oversight of launch operations and countdown management for unmanned NASA launches. NASA shares data with various national and international such as from the Greenhouse Gases Observing Satellite. Since 2011, NASA has been criticized for low cost efficiency, from 1946, the National Advisory Committee for Aeronautics had been experimenting with rocket planes such as the supersonic Bell X-1. In the early 1950s, there was challenge to launch a satellite for the International Geophysical Year. An effort for this was the American Project Vanguard, after the Soviet launch of the worlds first artificial satellite on October 4,1957, the attention of the United States turned toward its own fledgling space efforts. This led to an agreement that a new federal agency based on NACA was needed to conduct all non-military activity in space. The Advanced Research Projects Agency was created in February 1958 to develop technology for military application. On July 29,1958, Eisenhower signed the National Aeronautics and Space Act, a NASA seal was approved by President Eisenhower in 1959. Elements of the Army Ballistic Missile Agency and the United States Naval Research Laboratory were incorporated into NASA, earlier research efforts within the US Air Force and many of ARPAs early space programs were also transferred to NASA. In December 1958, NASA gained control of the Jet Propulsion Laboratory, NASA has conducted many manned and unmanned spaceflight programs throughout its history. Some missions include both manned and unmanned aspects, such as the Galileo probe, which was deployed by astronauts in Earth orbit before being sent unmanned to Jupiter, the experimental rocket-powered aircraft programs started by NACA were extended by NASA as support for manned spaceflight. This was followed by a space capsule program, and in turn by a two-man capsule program. This goal was met in 1969 by the Apollo program, however, reduction of the perceived threat and changing political priorities almost immediately caused the termination of most of these plans. NASA turned its attention to an Apollo-derived temporary space laboratory, to date, NASA has launched a total of 166 manned space missions on rockets, and thirteen X-15 rocket flights above the USAF definition of spaceflight altitude,260,000 feet. The X-15 was an NACA experimental rocket-powered hypersonic research aircraft, developed in conjunction with the US Air Force, the design featured a slender fuselage with fairings along the side containing fuel and early computerized control systems
NASA
–
1963 photo showing Dr. William H. Pickering, (center) JPL Director, President John F. Kennedy, (right). NASA Administrator James Webb in background. They are discussing the
Mariner program, with a model presented.
NASA
–
Seal of NASA
NASA
–
At launch control for the May 28, 1964,
Saturn I SA-6 launch.
Wernher von Braun is at center.
NASA
–
Mercury-Atlas 6 launch on February 20, 1962
3.
TRW Inc.
–
TRW Inc. was an American corporation involved in a variety of businesses, mainly aerospace, automotive, and credit reporting. It was a pioneer in multiple fields including electronic components, integrated circuits, computers, software, TRW built many spacecraft, including Pioneer 1, Pioneer 10, and several space-based observatories. It was #57 on the Fortune 500 list, and had 122,258 employees, tRW’s roots were founded in 1901, and it lasted for more than a century until being acquired by Northrop Grumman in 2002. Persons coming from TRW were important to build up corporations like SpaceX, in 1953, the company was recruited to lead the development of the United States first ICBM. Starting with the design by Convair, the multi-corporate team launched Atlas in 1957. It flew its full range in 1958, and was adapted to fly the Mercury astronauts into orbit, TRW also led development of the Titan missile, which was later adapted to fly the Gemini missions. The company served the US Air Force as systems engineers on all subsequent ICBM development efforts, in 1960, Congress spurred the formation of the non-profit Aerospace Corporation to provide systems engineering to the US government, but TRW continued to guide the ICBM efforts. TRW originated in 1901 with the Cleveland Cap Screw Company, founded by David Kurtz and their initial products were bolts with heads electrically welded to the shafts. In 1904, a welder named Charles E. Thompson adapted their process to making automobile engine valves, and, by 1915, Charles Thompson was named General Manager of the company, which became Thompson Products in 1926. Their experimental hollow sodium-cooled valves aided Charles Lindberghs solo flight across the Atlantic, in 1937, Thompson Motor Products bought J. A. Drake and Sons. The company made high performance valves that were used in racing engines of the day. Dale Drake bought the Offy engine design with his partner Louis Meyer in 1946 and won the Indianapolis 500 twenty-seven times, more than any other engine design. During the period leading up to World War II, through the end of the Korean war, Thompson Products was a key manufacturer of component parts for aircraft engines, including aircraft valves. The TAPCO plant, owned by the U. S. Government and it employed over 16,000 workers at the peak of WW II production. They grew frustrated with Howard Hughes’ management, and formed the Ramo-Wooldridge Corporation in September 1953, the detonation of a thermonuclear bomb by the Soviet Union spurred Trevor Gardner to form the Teapot Committee in October 1953. Chaired by John von Neumann, its purpose was to study the development of ballistic missiles, Ramo and Wooldridge were committee members, and Ramo-Wooldridge Corp. became the lead contractor of the resulting ICBM development effort, reporting to the United States Air Force. With continued backing from Thompson Products, Ramo-Wooldridge diversified into computers and electronic components and they also produced scientific spacecraft such as Pioneer 1. Thompson Products and Ramo-Wooldridge merged in October 1958 to form Thompson Ramo Wooldridge Inc. unofficially known as TRW, in February 1959, Jimmy Doolittle became Chairman of the Board of Space Technology Laboratories, the division which continued to support the Air Force ICBM efforts
TRW Inc.
–
TRW Inc.
4.
Space Shuttle
–
The Space Shuttle was a partially reusable low Earth orbital spacecraft system operated by the U. S. National Aeronautics and Space Administration, as part of the Space Shuttle program. Its official program name was Space Transportation System, taken from a 1969 plan for a system of reusable spacecraft of which it was the only item funded for development, the first of four orbital test flights occurred in 1981, leading to operational flights beginning in 1982. Five complete Shuttle systems were built and used on a total of 135 missions from 1981 to 2011, the Shuttle fleets total mission time was 1322 days,19 hours,21 minutes and 23 seconds. Shuttle components included the Orbiter Vehicle, a pair of solid rocket boosters. The Shuttle was launched vertically, like a rocket, with the two SRBs operating in parallel with the OVs three main engines, which were fueled from the ET. The SRBs were jettisoned before the vehicle reached orbit, and the ET was jettisoned just before orbit insertion, at the conclusion of the mission, the orbiter fired its OMS to de-orbit and re-enter the atmosphere. The orbiter then glided as a spaceplane to a landing, usually at the Shuttle Landing Facility of KSC or Rogers Dry Lake in Edwards Air Force Base. After landing at Edwards, the orbiter was back to the KSC on the Shuttle Carrier Aircraft. The first orbiter, Enterprise, was built in 1976, used in Approach, four fully operational orbiters were initially built, Columbia, Challenger, Discovery, and Atlantis. Of these, two were lost in accidents, Challenger in 1986 and Columbia in 2003, with a total of fourteen astronauts killed. A fifth operational orbiter, Endeavour, was built in 1991 to replace Challenger, the Space Shuttle was retired from service upon the conclusion of Atlantiss final flight on July 21,2011. Nixons post-Apollo NASA budgeting withdrew support of all components except the Shuttle. The vehicle consisted of a spaceplane for orbit and re-entry, fueled by liquid hydrogen and liquid oxygen tanks. The first of four orbital test flights occurred in 1981, leading to operational flights beginning in 1982, all launched from the Kennedy Space Center, Florida. The system was retired from service in 2011 after 135 missions, the program ended after Atlantis landed at the Kennedy Space Center on July 21,2011. Major missions included launching numerous satellites and interplanetary probes, conducting space science experiments, the first orbiter vehicle, named Enterprise, was built for the initial Approach and Landing Tests phase and lacked engines, heat shielding, and other equipment necessary for orbital flight. A total of five operational orbiters were built, and of these and it was used for orbital space missions by NASA, the US Department of Defense, the European Space Agency, Japan, and Germany. The United States funded Shuttle development and operations except for the Spacelab modules used on D1, sL-J was partially funded by Japan
Space Shuttle
–
Discovery lifts off at the start of
STS-120.
Space Shuttle
–
STS-129 ready for launch
Space Shuttle
–
President Nixon (right) with
NASA Administrator Fletcher in January 1972, three months before Congress approved funding for the Shuttle program
Space Shuttle
–
STS-1 on the launch pad, December 1980
5.
Space Shuttle Atlantis
–
Space Shuttle Atlantis is a Space Shuttle orbiter belonging to the National Aeronautics and Space Administration, the spaceflight and space exploration agency of the United States. Its maiden flight was STS-51-J from 3 to 7 October 1985, Atlantis embarked on its 33rd and final mission, also the final mission of a space shuttle, STS-135, on 8 July 2011. STS-134 by Endeavour was expected to be the flight before STS-135 was authorized in October 2010. STS-135 took advantage of the processing for the STS-335 Launch On Need mission that would have been necessary if STS-134s crew became stranded in orbit, Atlantis landed for the final time at the Kennedy Space Center on 21 July 2011. By the end of its mission, Atlantis had orbited the Earth a total of 4,848 times. Atlantis is named after RV Atlantis, a sailing ship that operated as the primary research vessel for the Woods Hole Oceanographic Institution from 1930 to 1966. Weight,151,315 pounds Length,122.17 feet Height,56.58 feet Wingspan,78.06 feet Atlantis was completed in half the time it took to build Space Shuttle Columbia. When it rolled out of the Palmdale assembly plant, weighing 151,315 lb, Atlantis is the lightest shuttle of the remaining fleet, weighing three pounds less than the Space Shuttle Endeavour. Space Shuttle Atlantis lifted off on its voyage on 3 October 1985, on mission STS-51-J. It flew one mission, STS-61-B, the second night launch in the shuttle program. Atlantis was then used for ten flights between 1988 and 1992, two of these, both flown in 1989, deployed the planetary probes Magellan to Venus and Galileo to Jupiter. With STS-30 Atlantis became the first shuttle to launch an interplanetary probe, during another mission, STS-37 flown in 1991, Atlantis deployed the Compton Gamma Ray Observatory. Beginning in 1995 with STS-71, Atlantis made seven flights to the former Russian space station Mir as part of the Shuttle-Mir Program. When linked, Atlantis and Mir together formed the largest spacecraft in orbit at the time, Shuttle Atlantis also delivered several vital components for the construction of the International Space Station. During the February 2001 mission STS-98 to the ISS, Atlantis delivered the Destiny Module, the five hour 25 minute third spacewalk performed by astronauts Robert Curbeam and Thomas Jones during STS-98 marked NASAs 100th extra vehicular activity in space. The Quest Joint Airlock, was flown and installed to the ISS by Atlantis during the mission STS-104 in July 2001. The successful installation of the airlock gave on-board space station crews the ability to stage repair, the first mission flown by Atlantis after the Space Shuttle Columbia disaster was STS-115, conducted during September 2006. The mission carried the P3/P4 truss segments and solar arrays to the ISS, on ISS assembly flight STS-122 in February 2008, Atlantis delivered the Columbus laboratory to the ISS
Space Shuttle Atlantis
–
Atlantis launching on the
STS-122 mission to dock with the
International Space Station in February 2008
Space Shuttle Atlantis
–
Space Shuttle Atlantis as it
transits the
Sun
Space Shuttle Atlantis
–
Atlantis docked to the International Space Station during STS-132 mission.
Space Shuttle Atlantis
–
Atlantis heads toward Earth orbit at the beginning of
STS-129.
6.
STS-37
–
The mission also featured two spacewalks, the first since 1985. Resumption of the countdown after the T-9 minute hold was delayed about 4 minutes 45 seconds because of two possible weather-condition violations of the launch commit criteria, both conditions were found acceptable and the launch countdown proceeded to a satisfactory launch to an inclination of 28.45 degrees. The primary payload, the Gamma Ray Observatory, was deployed on flight day 3, gROs high-gain antenna failed to deploy on command, it was finally freed and manually deployed by Ross and Apt during an unscheduled contingency space walk, the first since April 1985. GRO science instruments were Burst and Transient Source Experiment, Imaging Compton Telescope, Energetic Gamma Ray Experiment Telescope, GRO was the second of NASAs four Great Observatories. The Hubble Space Telescope, deployed during Mission STS-31 in April 1990, was the first, GRO was launched on a two-year mission to search for the high-energy celestial gamma ray emissions, which cannot penetrate Earths atmosphere. At about 35,000 pounds, GRO was the heaviest satellite to be deployed into orbit from the Shuttle. It was also designed to be the first satellite that could be refueled in orbit by Shuttle crews. The first U. S. extravehicular activity or spacewalk since 1985 was performed by Mission Specialists Jerry L. Ross, Ross and Apt were prepared for such a contingency, and Ross freed the antenna boom within 17 minutes after beginning the spacewalk. It was the first unscheduled contingency EVA since STS-51-D in April 1985, deployment occurred about 18,35 EST, approximately 4 1⁄2 hours after it was scheduled. The following day, on 8 April 1991, Ross and Apt made the first scheduled EVA since Mission STS-61-B in November 1985, the spacewalk was to test methods of moving crew members and equipment around the future Space Station Freedom. One of the experiments was to evaluate manual, mechanical and electrical power methods of moving carts around the outside of large structures in space, although all three methods worked, the astronauts reported that propelling the cart manually or hand-over-hand worked best. With both EVAs, Ross and Apt logged 10 hours and 49 minutes walking in space during STS-37, crew members also reported success with secondary experiments. During the second EVA, a stainless steel palm restraint bar punctured the pressure bladder of Apts right glove, however, the astronauts hand and silk comfort glove partially sealed the hole, resulting in no detectable depressurization. In fact, the puncture was not noticed until postflight examination, astronaut Pilot Kenneth Cameron was the primary operator of the Shuttle Amateur Radio Experiment, although all five crew members participated as amateur radio operators. Landing originally scheduled for 10 April 1991, but delayed one day due to conditions at Edwards. Orbiter returned to KSC18 April 1991, due to an incorrect call on winds aloft, Atlantis landed 623 feet short of the lakebed runways threshold marking. This did not present a problem, since the orbiter landed on the dry bed of Edwards. Had the landing been attempted at the Kennedy Space Center, the result would have been a touchdown on the paved underrun preceding the runway, landing speed was 168 KEAS,13 knots faster than the slowest landing of the Shuttle program, STS-28s 155 KEAS
STS-37
–
CGRO is grappled by Atlantis' RMS
STS-37
STS-37
–
Launch of Atlantis on STS-37.
STS-37
–
Ross during the first EVA; CGRO in the background
7.
Kennedy Space Center
–
The John F. Kennedy Space Center is one of ten National Aeronautics and Space Administration field centers. Since December 1968, Kennedy Space Center has been NASAs primary launch center of human spaceflight, Launch operations for the Apollo, Skylab and Space Shuttle programs were carried out from Kennedy Space Center Launch Complex 39 and managed by KSC. Located on the east coast of Florida, KSC is adjacent to Cape Canaveral Air Force Station, the management of the two entities work very closely together, share resources, and even own facilities on each others property. Additionally, the center manages launch of robotic and commercial missions, researches food production and In-Situ Resource Utilization for off Earth exploration. Since 2010, the center has worked to become a multi-user spaceport through industry partnerships, there are about 700 facilities grouped across the centers 144,000 acres. There is also a Visitor Complex open to the public on site, the military had been performing launch operations since 1949 at what would become Cape Canaveral Air Force Station. In December 1959, the Department of Defense transferred 5,000 personnel, President John F. Kennedys 1961 goal of a manned lunar landing before 1970 required an expansion of launch operations. On July 1,1962, the Launch Operations Directorate was separated from MSFC to become the Launch Operations Center, therefore, the decision was made to build a new LOC site located adjacent to Cape Canaveral on Merritt Island. NASA began land acquisition in 1962, buying title to 131 square miles, the major buildings in KSCs Industrial Area were designed by architect Charles Luckman. Construction began in November 1962, and Kennedy visited the site twice in 1962, on November 29,1963, the facility was given its current name by President Lyndon B. Johnson under Executive Order 11129. Johnsons order joined both the civilian LOC and the military Cape Canaveral station under the designation John F. Kennedy Space Center, spawning some confusion joining the two in the public mind. Located on Merritt Island, Florida, the center is north-northwest of Cape Canaveral on the Atlantic Ocean and it is 34 miles long and roughly six miles wide, covering 219 square miles. KSC is a major central Florida tourist destination and is one hours drive from the Orlando area. The Kennedy Space Center Visitor Complex offers public tours of the center, Center workers can encounter bald eagles, American alligators, wild boars, eastern diamondback rattlesnakes, the endangered Florida panther and Florida manatees. From 1967 through 1973, there were 13 Saturn V launches, the first of two unmanned flights, Apollo 4 on November 9,1967, was also the first rocket launch from KSC. The Saturn Vs first manned launch on December 21,1968 was Apollo 8s lunar orbiting mission, the next two missions tested the Lunar Module, Apollo 9 and Apollo 10. Apollo 11, launched from Pad A on July 16,1969, Apollo 12 followed four months later. From 1970–1972, the Apollo program concluded at KSC with the launches of missions 13 through 17, on May 14,1973, the last Saturn V launch put the Skylab space station in orbit from Pad 39A
Kennedy Space Center
–
Aerial view of
KSC Headquarters looking south
Kennedy Space Center
–
KSC shown in white;
CCAFS in green
Kennedy Space Center
–
A Saturn V carrying
Apollo 15 rolls out to Pad 39A in 1971 on
Mobile Launch Platform 1.
Kennedy Space Center
–
Shuttle Discovery launching from Pad 39A on
STS-60, February 3, 1994
8.
Kennedy Space Center Launch Complex 39
–
Launch Complex 39 is a rocket launch site at the John F. Kennedy Space Center on Merritt Island in Florida, United States. The site and its collection of facilities were built for the Apollo program. As of 2017, only Launch Complex 39A is active, launching SpaceXs Falcon 9. LC-39 is also being modified to support launches of the SpaceXs Dragon 2 and Falcon Heavy, as well as NASAs Space Launch System, with a new, smaller pad, C, added to support smaller launches. SpaceX leases Launch Pad 39A from NASA and has modified the pad to support Falcon Heavy launches in 2017 and beyond. NASA began modifying Launch Pad 39B in 2007 to accommodate the now defunct Project Constellation, Pad C was originally planned but never built for Apollo, and would have been a copy of pads 39A and 39B. A smaller pad, designated 39C was constructed from January to June 2015 to accommodate small-class vehicles, NASA launches from LC-39A and 39B have been supervised from the NASA Launch Control Center, located 3 miles from the launch pads. LC-39 is one of launch sites that share radar and tracking services of the Eastern Test Range. During the 1920s, Peter E. Studebaker Jr. son of the automobile magnate, in 1948, the Navy transferred the former Banana River Naval Air Station located south of Cape Canaveral, to the Air Force for use in testing captured German V-2 rockets. The sites location on the East Florida coast was ideal for this purpose in that launches would be over the ocean and this site became the Joint Long Range Proving Ground in 1949, and was renamed Patrick Air Force Base in 1950. The Air Force annexed part of Cape Canaveral to the North in 1951, forming the Air Force Missile Test Center, Missile and rocketry testing and development would take place here through the 1950s. After the creation of NASA in 1958, the CCAFS launch pads were used for NASAs civilian unmanned and manned launches, including those of Project Mercury, in 1961, President Kennedy proposed to Congress the goal of landing a man on the Moon by the end of the decade. NASA began acquisition of land in 1962, taking title to 131 square miles by outright purchase, on July 1,1962, the site was named the Launch Operations Center. At the time, the highest numbered launch pad on CCAFS was Launch Complex 37 and it was designed to handle launches of the Saturn V rocket, at the time the largest, most powerful rocket then designed, required to take Apollo to the Moon. Initial plans included four pads evenly spaced 8,700 feet apart to damage in the event of an explosion on the pad. Three were scheduled for construction and two would have built at a later date. The numbering of the pads at the time was from north to south, with the northernmost being 39A, Pad 39A was never built, and 39C became 39A in 1963. With todays numbering, 39C would have been north of 39B, Pad 39E would have been due north of the mid-distance between 39C and 39D, with 39E forming the top of a triangle, and equidistant from 39C and 39D
Kennedy Space Center Launch Complex 39
–
An aerial view of Launch Complex 39
Kennedy Space Center Launch Complex 39
–
Apollo-Saturn 506 with Apollo 11 spacecraft being moved from the VAB to LC39A
Kennedy Space Center Launch Complex 39
–
Apollo era walkway and
white room, on display at
Kennedy Space Center Visitor Complex
Kennedy Space Center Launch Complex 39
–
Warning lamps showing the planned 3 pads including the unbuilt Pad C
9.
Geocentric orbit
–
A geocentric orbit or Earth orbit involves any object orbiting the Earth, such as the Moon or artificial satellites. In 1997 NASA estimated there were approximately 2,465 artificial satellite orbiting the Earth and 6,216 pieces of space debris as tracked by the Goddard Space Flight Center. Over 16,291 previously launched objects have decayed into the Earths atmosphere, altitude as used here, the height of an object above the average surface of the Earths oceans. Analemma a term in astronomy used to describe the plot of the positions of the Sun on the celestial sphere throughout one year, apogee is the farthest point that a satellite or celestial body can go from Earth, at which the orbital velocity will be at its minimum. Eccentricity a measure of how much an orbit deviates from a perfect circle, eccentricity is strictly defined for all circular and elliptical orbits, and parabolic and hyperbolic trajectories. Equatorial plane as used here, an imaginary plane extending from the equator on the Earth to the celestial sphere, escape velocity as used here, the minimum velocity an object without propulsion needs to have to move away indefinitely from the Earth. An object at this velocity will enter a parabolic trajectory, above this velocity it will enter a hyperbolic trajectory, impulse the integral of a force over the time during which it acts. Inclination the angle between a plane and another plane or axis. In the sense discussed here the reference plane is the Earths equatorial plane, orbital characteristics the six parameters of the Keplerian elements needed to specify that orbit uniquely. Orbital period as defined here, time it takes a satellite to make one orbit around the Earth. Perigee is the nearest approach point of a satellite or celestial body from Earth, sidereal day the time it takes for a celestial object to rotate 360°. For the Earth this is,23 hours,56 minutes,4.091 seconds, solar time as used here, the local time as measured by a sundial. Velocity an objects speed in a particular direction, since velocity is defined as a vector, both speed and direction are required to define it. The following is a list of different geocentric orbit classifications, Low Earth orbit - Geocentric orbits ranging in altitude from 160 kilometers to 2,000 kilometres above mean sea level. At 160 km, one revolution takes approximately 90 minutes, medium Earth orbit - Geocentric orbits with altitudes at apogee ranging between 2,000 kilometres and that of the geosynchronous orbit at 35,786 kilometres. Geosynchronous orbit - Geocentric circular orbit with an altitude of 35,786 kilometres, the period of the orbit equals one sidereal day, coinciding with the rotation period of the Earth. The speed is approximately 3,000 metres per second, high Earth orbit - Geocentric orbits with altitudes at apogee higher than that of the geosynchronous orbit. A special case of high Earth orbit is the elliptical orbit
Geocentric orbit
–
General
Geocentric orbit
–
Low (cyan) and Medium (yellow) Earth orbit regions to scale. The black dashed line is the geosynchronous orbit. The green dashed line is the 20,230 km orbit used for
GPS satellites.
10.
Low Earth orbit
–
A low Earth orbit is an orbit around Earth with an altitude between 160 kilometers, and 2,000 kilometers. Objects below approximately 160 kilometers will experience very rapid orbital decay, with the exception of the 24 human beings who flew lunar flights in the Apollo program during the four-year period spanning 1968 through 1972, all human spaceflights have taken place in LEO or below. The International Space Station conducts operations in LEO, the altitude record for a human spaceflight in LEO was Gemini 11 with an apogee of 1,374.1 kilometers. All crewed space stations to date, as well as the majority of satellites, have been in LEO, objects in LEO encounter atmospheric drag from gases in the thermosphere or exosphere, depending on orbit height. Due to atmospheric drag, satellites do not usually orbit below 300 km, objects in LEO orbit Earth between the denser part of the atmosphere and below the inner Van Allen radiation belt. The mean orbital velocity needed to maintain a stable low Earth orbit is about 7.8 km/s, calculated for circular orbit of 200 km it is 7.79 km/s and for 1500 km it is 7.12 km/s. The delta-v needed to achieve low Earth orbit starts around 9.4 km/s, atmospheric and gravity drag associated with launch typically adds 1. 3–1.8 km/s to the launch vehicle delta-v required to reach normal LEO orbital velocity of around 7.8 km/s. Equatorial low Earth orbits are a subset of LEO and these orbits, with low inclination to the Equator, allow rapid revisit times and have the lowest delta-v requirement of any orbit. Orbits with an inclination angle to the equator are usually called polar orbits. Higher orbits include medium Earth orbit, sometimes called intermediate circular orbit, orbits higher than low orbit can lead to early failure of electronic components due to intense radiation and charge accumulation. Although the Earths pull due to gravity in LEO is not much less than on the surface of the Earth, people, a low Earth orbit is simplest and cheapest for satellite placement. It provides high bandwidth and low communication time lag, but satellites in LEO will not be visible from any point on the Earth at all times. Earth observation satellites and spy satellites use LEO as they are able to see the surface of the Earth more clearly as they are not so far away and they are also able to traverse the surface of the Earth. A majority of satellites are placed in LEO, making one complete revolution around the Earth in about 90 minutes. The International Space Station is in a LEO about 400 km above the Earths surface, since it requires less energy to place a satellite into a LEO and the LEO satellite needs less powerful amplifiers for successful transmission, LEO is used for many communication applications. Because these LEO orbits are not geostationary, a network of satellites is required to provide continuous coverage, lower orbits also aid remote sensing satellites because of the added detail that can be gained. Remote sensing satellites can also take advantage of sun-synchronous LEO orbits at an altitude of about 800 km, envisat is one example of an Earth observation satellite that makes use of this particular type of LEO. The LEO environment is becoming congested with space debris due to the frequency of object launches and this has caused growing concern in recent years, since collisions at orbital velocities can easily be dangerous, and even deadly
Low Earth orbit
–
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Low Earth orbit
–
Comparison of
GPS,
GLONASS,
Galileo and
Compass (medium earth orbit) satellite navigation system orbits with the
International Space Station,
Hubble Space Telescope and
Iridium constellation orbits,
Geostationary Earth Orbit, and the nominal size of the
Earth. The
Moon 's orbit is around 9 times larger (in radius and length) than geostationary orbit.
11.
Orbital eccentricity
–
The orbital eccentricity of an astronomical object is a parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is an orbit, values between 0 and 1 form an elliptical orbit,1 is a parabolic escape orbit. The term derives its name from the parameters of conic sections and it is normally used for the isolated two-body problem, but extensions exist for objects following a rosette orbit through the galaxy. In a two-body problem with inverse-square-law force, every orbit is a Kepler orbit, the eccentricity of this Kepler orbit is a non-negative number that defines its shape. The limit case between an ellipse and a hyperbola, when e equals 1, is parabola, radial trajectories are classified as elliptic, parabolic, or hyperbolic based on the energy of the orbit, not the eccentricity. Radial orbits have zero angular momentum and hence eccentricity equal to one, keeping the energy constant and reducing the angular momentum, elliptic, parabolic, and hyperbolic orbits each tend to the corresponding type of radial trajectory while e tends to 1. For a repulsive force only the trajectory, including the radial version, is applicable. For elliptical orbits, a simple proof shows that arcsin yields the projection angle of a circle to an ellipse of eccentricity e. For example, to view the eccentricity of the planet Mercury, next, tilt any circular object by that angle and the apparent ellipse projected to your eye will be of that same eccentricity. From Medieval Latin eccentricus, derived from Greek ἔκκεντρος ekkentros out of the center, from ἐκ- ek-, eccentric first appeared in English in 1551, with the definition a circle in which the earth, sun. Five years later, in 1556, a form of the word was added. The eccentricity of an orbit can be calculated from the state vectors as the magnitude of the eccentricity vector, e = | e | where. For elliptical orbits it can also be calculated from the periapsis and apoapsis since rp = a and ra = a, where a is the semimajor axis. E = r a − r p r a + r p =1 −2 r a r p +1 where, rp is the radius at periapsis. For Earths annual orbit path, ra/rp ratio = longest_radius / shortest_radius ≈1.034 relative to center point of path, the eccentricity of the Earths orbit is currently about 0.0167, the Earths orbit is nearly circular. Venus and Neptune have even lower eccentricity, over hundreds of thousands of years, the eccentricity of the Earths orbit varies from nearly 0.0034 to almost 0.058 as a result of gravitational attractions among the planets. The table lists the values for all planets and dwarf planets, Mercury has the greatest orbital eccentricity of any planet in the Solar System. Such eccentricity is sufficient for Mercury to receive twice as much solar irradiation at perihelion compared to aphelion, before its demotion from planet status in 2006, Pluto was considered to be the planet with the most eccentric orbit
Orbital eccentricity
–
Gravity Simulator plot of the changing orbital eccentricity of
Mercury,
Venus,
Earth, and
Mars over the next 50,000 years. The arrows indicate the different scales used. The 0 point on this plot is the year 2007.
Orbital eccentricity
–
An elliptic, parabolic and hyperbolic
Kepler orbit: elliptic (eccentricity = 0.7) parabolic (eccentricity = 1) hyperbolic orbit (eccentricity = 1.3)
12.
Apsis
–
An apsis is an extreme point in an objects orbit. The word comes via Latin from Greek and is cognate with apse, for elliptic orbits about a larger body, there are two apsides, named with the prefixes peri- and ap-, or apo- added to a reference to the thing being orbited. For a body orbiting the Sun, the point of least distance is the perihelion, the terms become periastron and apastron when discussing orbits around other stars. For any satellite of Earth including the Moon the point of least distance is the perigee, for objects in Lunar orbit, the point of least distance is the pericynthion and the greatest distance the apocynthion. For any orbits around a center of mass, there are the terms pericenter and apocenter, periapsis and apoapsis are equivalent alternatives. A straight line connecting the pericenter and apocenter is the line of apsides and this is the major axis of the ellipse, its greatest diameter. For a two-body system the center of mass of the lies on this line at one of the two foci of the ellipse. When one body is larger than the other it may be taken to be at this focus. Historically, in systems, apsides were measured from the center of the Earth. In orbital mechanics, the apsis technically refers to the distance measured between the centers of mass of the central and orbiting body. However, in the case of spacecraft, the family of terms are used to refer to the orbital altitude of the spacecraft from the surface of the central body. The arithmetic mean of the two limiting distances is the length of the axis a. The geometric mean of the two distances is the length of the semi-minor axis b, the geometric mean of the two limiting speeds is −2 ε = μ a which is the speed of a body in a circular orbit whose radius is a. The words pericenter and apocenter are often seen, although periapsis/apoapsis are preferred in technical usage, various related terms are used for other celestial objects. The -gee, -helion and -astron and -galacticon forms are used in the astronomical literature when referring to the Earth, Sun, stars. The suffix -jove is occasionally used for Jupiter, while -saturnium has very rarely used in the last 50 years for Saturn. The -gee form is used as a generic closest approach to planet term instead of specifically applying to the Earth. During the Apollo program, the terms pericynthion and apocynthion were used when referring to the Moon, regarding black holes, the term peri/apomelasma was used by physicist Geoffrey A. Landis in 1998 before peri/aponigricon appeared in the scientific literature in 2002
Apsis
–
The perihelion and aphelion points of the
inner planets of the Solar System
Apsis
–
(1) furthest
Apsis
–
The perihelion and aphelion points of the
outer planets of the Solar System
13.
Orbital inclination
–
Orbital inclination measures the tilt of an objects orbit around a celestial body. It is expressed as the angle between a plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Earth directly above the equator, the plane of the orbit is the same as the Earths equatorial plane. The general case is that the orbit is tilted, it spends half an orbit over the northern hemisphere. If the orbit swung between 20° north latitude and 20° south latitude, then its orbital inclination would be 20°, the inclination is one of the six orbital elements describing the shape and orientation of a celestial orbit. It is the angle between the plane and the plane of reference, normally stated in degrees. For a satellite orbiting a planet, the plane of reference is usually the plane containing the planets equator, for planets in the Solar System, the plane of reference is usually the ecliptic, the plane in which the Earth orbits the Sun. This reference plane is most practical for Earth-based observers, therefore, Earths inclination is, by definition, zero. Inclination could instead be measured with respect to another plane, such as the Suns equator or the invariable plane, the inclination of orbits of natural or artificial satellites is measured relative to the equatorial plane of the body they orbit, if they orbit sufficiently closely. The equatorial plane is the perpendicular to the axis of rotation of the central body. An inclination of 30° could also be described using an angle of 150°, the convention is that the normal orbit is prograde, an orbit in the same direction as the planet rotates. Inclinations greater than 90° describe retrograde orbits, thus, An inclination of 0° means the orbiting body has a prograde orbit in the planets equatorial plane. An inclination greater than 0° and less than 90° also describe prograde orbits, an inclination of 63. 4° is often called a critical inclination, when describing artificial satellites orbiting the Earth, because they have zero apogee drift. An inclination of exactly 90° is an orbit, in which the spacecraft passes over the north and south poles of the planet. An inclination greater than 90° and less than 180° is a retrograde orbit, an inclination of exactly 180° is a retrograde equatorial orbit. For gas giants, the orbits of moons tend to be aligned with the giant planets equator, the inclination of exoplanets or members of multiple stars is the angle of the plane of the orbit relative to the plane perpendicular to the line-of-sight from Earth to the object. An inclination of 0° is an orbit, meaning the plane of its orbit is parallel to the sky. An inclination of 90° is an orbit, meaning the plane of its orbit is perpendicular to the sky
Orbital inclination
–
Fig. 1: One view of inclination i (green) and other
orbital parameters
14.
Longitude of the ascending node
–
The longitude of the ascending node is one of the orbital elements used to specify the orbit of an object in space. It is the angle from a direction, called the origin of longitude, to the direction of the ascending node. The ascending node is the point where the orbit of the passes through the plane of reference. Commonly used reference planes and origins of longitude include, For a geocentric orbit, Earths equatorial plane as the plane. In this case, the longitude is called the right ascension of the ascending node. The angle is measured eastwards from the First Point of Aries to the node, for a heliocentric orbit, the ecliptic as the reference plane, and the First Point of Aries as the origin of longitude. The angle is measured counterclockwise from the First Point of Aries to the node, the angle is measured eastwards from north to the node. pp.40,72,137, chap. In the case of a star known only from visual observations, it is not possible to tell which node is ascending. In this case the orbital parameter which is recorded is the longitude of the node, Ω, here, n=<nx, ny, nz> is a vector pointing towards the ascending node. The reference plane is assumed to be the xy-plane, and the origin of longitude is taken to be the positive x-axis, K is the unit vector, which is the normal vector to the xy reference plane. For non-inclined orbits, Ω is undefined, for computation it is then, by convention, set equal to zero, that is, the ascending node is placed in the reference direction, which is equivalent to letting n point towards the positive x-axis. Kepler orbits Equinox Orbital node perturbation of the plane can cause revolution of the ascending node
Longitude of the ascending node
–
The longitude of the
ascending node.
15.
X-ray
–
X-radiation is a form of electromagnetic radiation. Most X-rays have a wavelength ranging from 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz, X-ray wavelengths are shorter than those of UV rays and typically longer than those of gamma rays. Spelling of X-ray in the English language includes the variants x-ray, xray, X-rays with high photon energies are called hard X-rays, while those with lower energy are called soft X-rays. Due to their ability, hard X-rays are widely used to image the inside of objects, e. g. in medical radiography. The term X-ray is metonymically used to refer to an image produced using this method. Since the wavelengths of hard X-rays are similar to the size of atoms they are useful for determining crystal structures by X-ray crystallography. By contrast, soft X-rays are easily absorbed in air, the length of 600 eV X-rays in water is less than 1 micrometer. There is no consensus for a definition distinguishing between X-rays and gamma rays, one common practice is to distinguish between the two types of radiation based on their source, X-rays are emitted by electrons, while gamma rays are emitted by the atomic nucleus. This definition has problems, other processes also can generate these high-energy photons. One common alternative is to distinguish X- and gamma radiation on the basis of wavelength, with radiation shorter than some arbitrary wavelength, such as 10−11 m and this criterion assigns a photon to an unambiguous category, but is only possible if wavelength is known. Occasionally, one term or the other is used in specific contexts due to precedent, based on measurement technique. Thus, gamma-rays generated for medical and industrial uses, for radiotherapy, in the ranges of 6–20 MeV. X-ray photons carry enough energy to ionize atoms and disrupt molecular bonds and this makes it a type of ionizing radiation, and therefore harmful to living tissue. A very high radiation dose over a period of time causes radiation sickness. In medical imaging this increased risk is generally greatly outweighed by the benefits of the examination. The ionizing capability of X-rays can be utilized in treatment to kill malignant cells using radiation therapy. It is also used for material characterization using X-ray spectroscopy, hard X-rays can traverse relatively thick objects without being much absorbed or scattered. For this reason, X-rays are widely used to image the inside of visually opaque objects, the most often seen applications are in medical radiography and airport security scanners, but similar techniques are also important in industry and research
X-ray
–
Spectrum of the X-rays emitted by an X-ray tube with a
rhodium target, operated at 60
kV. The smooth, continuous curve is due to
bremsstrahlung, and the spikes are
characteristic K lines for rhodium atoms.
X-ray
–
X-rays are part of the
electromagnetic spectrum, with wavelengths shorter than
visible light. Different applications use different parts of the X-ray spectrum.
X-ray
–
A
chest radiograph of a female, demonstrating a
hiatus hernia
X-ray
–
An arm radiograph, demonstrating broken
ulna and
radius with implanted
internal fixation.
16.
Gamma ray
–
Gamma ray, denoted by the lower-case Greek letter gamma, is penetrating electromagnetic radiation of a kind arising from the radioactive decay of atomic nuclei. It consists of photons in the highest observed range of photon energy, paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays, Rutherford had previously discovered two other types of radioactive decay, which he named alpha and beta rays. Gamma rays are able to ionize atoms, and are thus biologically hazardous. The decay of a nucleus from a high energy state to a lower energy state. Natural sources of gamma rays on Earth are observed in the decay of radionuclides. There are rare terrestrial natural sources, such as lightning strikes and terrestrial gamma-ray flashes, However, a large fraction of such astronomical gamma rays are screened by Earths atmosphere and can only be detected by spacecraft. Gamma rays typically have frequencies above 10 exahertz, and therefore have energies above 100 keV and wavelengths less than 10 picometers, However, this is not a strict definition, but rather only a rule-of-thumb description for natural processes. Electromagnetic radiation from radioactive decay of nuclei is referred to as gamma rays no matter its energy. This radiation commonly has energy of a few hundred keV, in astronomy, gamma rays are defined by their energy, and no production process needs to be specified. The energies of gamma rays from astronomical sources range to over 10 TeV, a notable example is the extremely powerful bursts of high-energy radiation referred to as long duration gamma-ray bursts, of energies higher than can be produced by radioactive decay. These bursts of gamma rays are thought to be due to the collapse of stars called hypernovae, the first gamma ray source to be discovered historically was the radioactive decay process called gamma decay. In this type of decay, a nucleus emits a gamma ray almost immediately upon formation. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900, However, Villard did not consider naming them as a different fundamental type. Rutherford also noted that gamma rays were not deflected by a field, another property making them unlike alpha. Gamma rays were first thought to be particles with mass, like alpha, Rutherford initially believed that they might be extremely fast beta particles, but their failure to be deflected by a magnetic field indicated that they had no charge. In 1914, gamma rays were observed to be reflected from crystal surfaces, Rutherford and his coworker Edward Andrade measured the wavelengths of gamma rays from radium, and found that they were similar to X-rays, but with shorter wavelengths and higher frequency. This was eventually recognized as giving them more energy per photon
Gamma ray
–
Gamma rays are emitted during
nuclear fission in nuclear explosions.
Gamma ray
–
Illustration of an emission of a gamma ray (γ) from an atomic nucleus
Gamma ray
Gamma ray
–
A
hypernova. Artist's illustration showing the life of a
massive star as
nuclear fusion converts lighter elements into heavier ones. When fusion no longer generates enough pressure to counteract gravity, the star rapidly collapses to form a
black hole. Theoretically, energy may be released during the collapse along the axis of rotation to form a long duration
gamma-ray burst.
17.
Kiloelectronvolt
–
In physics, the electronvolt is a unit of energy equal to approximately 1. 6×10−19 joules. By definition, it is the amount of energy gained by the charge of an electron moving across an electric potential difference of one volt. Thus it is 1 volt multiplied by the elementary charge, therefore, one electronvolt is equal to 6981160217662079999♠1. 6021766208×10−19 J. The electronvolt is not a SI unit, and its definition is empirical, like the elementary charge on which it is based, it is not an independent quantity but is equal to 1 J/C √2hα / μ0c0. It is a unit of energy within physics, widely used in solid state, atomic, nuclear. It is commonly used with the metric prefixes milli-, kilo-, in some older documents, and in the name Bevatron, the symbol BeV is used, which stands for billion electronvolts, it is equivalent to the GeV. By mass–energy equivalence, the electronvolt is also a unit of mass and it is common in particle physics, where units of mass and energy are often interchanged, to express mass in units of eV/c2, where c is the speed of light in vacuum. It is common to express mass in terms of eV as a unit of mass. The mass equivalent of 1 eV/c2 is 1 eV / c 2 = ⋅1 V2 =1.783 ×10 −36 kg. For example, an electron and a positron, each with a mass of 0.511 MeV/c2, the proton has a mass of 0.938 GeV/c2. In general, the masses of all hadrons are of the order of 1 GeV/c2, the unified atomic mass unit,1 gram divided by Avogadros number, is almost the mass of a hydrogen atom, which is mostly the mass of the proton. To convert to megaelectronvolts, use the formula,1 u =931.4941 MeV/c2 =0.9314941 GeV/c2, in high-energy physics, the electronvolt is often used as a unit of momentum. A potential difference of 1 volt causes an electron to gain an amount of energy and this gives rise to usage of eV as units of momentum, for the energy supplied results in acceleration of the particle. The dimensions of units are LMT−1. The dimensions of units are L2MT−2. Then, dividing the units of energy by a constant that has units of velocity. In the field of particle physics, the fundamental velocity unit is the speed of light in vacuum c. Thus, dividing energy in eV by the speed of light, the fundamental velocity constant c is often dropped from the units of momentum by way of defining units of length such that the value of c is unity
Kiloelectronvolt
–
γ:
Gamma rays
18.
Picometre
–
The picometre or picometer is a unit of length in the metric system, equal to 1×10−12 m, or one trillionth of a metre, which is the SI base unit of length. The picometre is one thousandth of a nanometre, one millionth of a micrometre, the symbol µµ was once used for it. It is also one hundredth of an angstrom, a recognised unit of length. The picometres length is of an such that its application is almost entirely confined to particle physics, quantum physics, chemistry. Atoms are between 62 and 520 pm in diameter, and the length of a carbon-carbon single bond is 154 pm. Smaller units still may be used to describe smaller particles, such as hadrons and the upper limits of possible size for fermion point particles
Picometre
–
A simplified representation of a
helium atom, having an estimated (calculated) diameter of 62 picometres
19.
Energetic Gamma Ray Experiment Telescope
–
The Energetic Gamma Ray Experiment Telescope was one of four instruments outfitted on NASA’s Compton Gamma Ray Observatory satellite. Since lower energy gamma rays cannot be detected on Earth’s surface. EGRET was created for the purpose of detecting and collecting data on gamma rays ranging in level from 30 MeV to 30 GeV. To accomplish its task, EGRET was equipped with a chamber, calorimeter. The spark chamber was used to induce a process called pair production as a gamma ray entered the telescope. The calorimeter on the telescope was used to record the data from the electron or positron. To reject other energy rays that would skew the data, scientists covered the telescope with a plastic scintillator anti-coincidence dome, the dome acted as a shield for the telescope and blocked out any unwanted energy rays. The telescope was calibrated to record gamma rays entering the telescope at certain angles. As these gamma rays entered the telescope, the rays went through the spark chamber. The calorimeter then detected the electron or positron and recorded its data, from EGRET’s finds, scientists have affirmed many long-standing theories about energy waves in space. Scientists have also been able to categorize and characterize four pulsars, scientists were able to map an entire sky of gamma rays with EGRETs results as well as find out interesting facts about Earth’s Moon and the Sun. EGRET is a predecessor of the Fermi Gamma-ray Space Telescope LAT, the chamber would manipulate the gamma ray into a way that it could be recorded. The sensor would capture and record the characteristics of the gamma ray, finally, the protective covering would block out any unwanted energy rays. With the purpose of detecting individual gamma rays ranging from 30 MeV to 30 GeV, EGRET was equipped with a plastic scintillator anti-coincidence dome, spark chamber, starting from the outside of the telescope, scientists covered EGRET with a plastic scintillator anti-coincidence dome. The dome acted as a shield, blocking any unwanted energy waves from entering the telescope, in order to induce this process, scientists assembled a multilevel thin-plate spark chamber within the telescope. A spark chamber is basically a chamber with many plates of metal, finally, to record the data from the electron or positron about the gamma ray, scientists equipped EGRET with a thallium-activated sodium iodide calorimeter at its base. The calorimeter captured the resolution of the rays that entered EGRET. Since NASA scientists wanted only certain types of rays to be processed and recorded
Energetic Gamma Ray Experiment Telescope
–
The instrument's logo.
20.
Space observatory
–
A space telescope or space observatory is an instrument located in outer space to observe distant planets, galaxies and other astronomical objects. Space telescopes avoid many of the problems of ground-based observatories, such as pollution and distortion of electromagnetic radiation. In addition, ultraviolet frequencies, X-rays and gamma rays are blocked by the Earths atmosphere, Space telescopes are distinct from other imaging satellites pointed toward Earth for purposes of espionage, weather analysis and other types of information gathering. Spitzers proposal called for a telescope that would not be hindered by Earths atmosphere. Performing astronomy from ground-based observatories on Earth is limited by the filtering, some terrestrial telescopes can reduce atmospheric effects with adaptive optics. A telescope orbiting Earth outside the atmosphere is subject neither to twinkling nor to light pollution from artificial light sources on Earth, as a result, the angular resolution of space telescopes is often much smaller than a ground-based telescope with a similar aperture. Infrared and ultraviolet are also largely blocked, however, all these advantages do come with a price. Space telescopes are much more expensive to build than ground-based telescopes, due to their location, space telescopes are also extremely difficult to maintain. The Hubble Space Telescope was serviced by the Space Shuttle while many other space telescopes cannot be serviced at all, Space observatories can generally be divided into two classes, missions which map the entire sky, and observatories which focus on selected astronomical objects or parts of the sky. Many space observatories have already completed their missions, while others continue operating, satellites have been launched and operated by NASA, ISRO, ESA, Japanese Space Agency and the Soviet space program later succeeded by Roskosmos of Russia. Many space telescopes have been launched, as of February 2017, over 20 telescopes are known to be operational
Space observatory
–
The Hubble Space Telescope, one of the
Great Observatories.
Space observatory
–
Spitzer, Hubble and XMM with their most important parts depicted
Space observatory
–
rightSpace observatories and their wavelength working ranges
Space observatory
–
Space observatories and their wavelength working range
21.
Photons
–
A photon is an elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force. The photon has zero rest mass and is moving at the speed of light. Like all elementary particles, photons are currently best explained by quantum mechanics and exhibit wave–particle duality, exhibiting properties of both waves and particles. For example, a photon may be refracted by a lens and exhibit wave interference with itself. The quanta in a light wave cannot be spatially localized, some defined physical parameters of a photon are listed. The modern concept of the photon was developed gradually by Albert Einstein in the early 20th century to explain experimental observations that did not fit the classical model of light. The benefit of the model was that it accounted for the frequency dependence of lights energy. The photon model accounted for observations, including the properties of black-body radiation. In that model, light was described by Maxwells equations, in 1926 the optical physicist Frithiof Wolfers and the chemist Gilbert N. Lewis coined the name photon for these particles. After Arthur H. Compton won the Nobel Prize in 1927 for his studies, most scientists accepted that light quanta have an independent existence. In the Standard Model of particle physics, photons and other particles are described as a necessary consequence of physical laws having a certain symmetry at every point in spacetime. The intrinsic properties of particles, such as charge, mass and it has been applied to photochemistry, high-resolution microscopy, and measurements of molecular distances. Recently, photons have been studied as elements of quantum computers, in 1900, the German physicist Max Planck was studying black-body radiation and suggested that the energy carried by electromagnetic waves could only be released in packets of energy. In his 1901 article in Annalen der Physik he called these packets energy elements, the word quanta was used before 1900 to mean particles or amounts of different quantities, including electricity. In 1905, Albert Einstein suggested that waves could only exist as discrete wave-packets. He called such a wave-packet the light quantum, the name photon derives from the Greek word for light, φῶς. Arthur Compton used photon in 1928, referring to Gilbert N. Lewis, the name was suggested initially as a unit related to the illumination of the eye and the resulting sensation of light and was used later in a physiological context. Although Wolferss and Lewiss theories were contradicted by many experiments and never accepted, in physics, a photon is usually denoted by the symbol γ
Photons
–
Large Hadron Collider tunnel at
CERN
22.
Electronvolt
–
In physics, the electronvolt is a unit of energy equal to approximately 1. 6×10−19 joules. By definition, it is the amount of energy gained by the charge of an electron moving across an electric potential difference of one volt. Thus it is 1 volt multiplied by the elementary charge, therefore, one electronvolt is equal to 6981160217662079999♠1. 6021766208×10−19 J. The electronvolt is not a SI unit, and its definition is empirical, like the elementary charge on which it is based, it is not an independent quantity but is equal to 1 J/C √2hα / μ0c0. It is a unit of energy within physics, widely used in solid state, atomic, nuclear. It is commonly used with the metric prefixes milli-, kilo-, in some older documents, and in the name Bevatron, the symbol BeV is used, which stands for billion electronvolts, it is equivalent to the GeV. By mass–energy equivalence, the electronvolt is also a unit of mass and it is common in particle physics, where units of mass and energy are often interchanged, to express mass in units of eV/c2, where c is the speed of light in vacuum. It is common to express mass in terms of eV as a unit of mass. The mass equivalent of 1 eV/c2 is 1 eV / c 2 = ⋅1 V2 =1.783 ×10 −36 kg. For example, an electron and a positron, each with a mass of 0.511 MeV/c2, the proton has a mass of 0.938 GeV/c2. In general, the masses of all hadrons are of the order of 1 GeV/c2, the unified atomic mass unit,1 gram divided by Avogadros number, is almost the mass of a hydrogen atom, which is mostly the mass of the proton. To convert to megaelectronvolts, use the formula,1 u =931.4941 MeV/c2 =0.9314941 GeV/c2, in high-energy physics, the electronvolt is often used as a unit of momentum. A potential difference of 1 volt causes an electron to gain an amount of energy and this gives rise to usage of eV as units of momentum, for the energy supplied results in acceleration of the particle. The dimensions of units are LMT−1. The dimensions of units are L2MT−2. Then, dividing the units of energy by a constant that has units of velocity. In the field of particle physics, the fundamental velocity unit is the speed of light in vacuum c. Thus, dividing energy in eV by the speed of light, the fundamental velocity constant c is often dropped from the units of momentum by way of defining units of length such that the value of c is unity
Electronvolt
–
γ:
Gamma rays
23.
Low earth orbit
–
A low Earth orbit is an orbit around Earth with an altitude between 160 kilometers, and 2,000 kilometers. Objects below approximately 160 kilometers will experience very rapid orbital decay, with the exception of the 24 human beings who flew lunar flights in the Apollo program during the four-year period spanning 1968 through 1972, all human spaceflights have taken place in LEO or below. The International Space Station conducts operations in LEO, the altitude record for a human spaceflight in LEO was Gemini 11 with an apogee of 1,374.1 kilometers. All crewed space stations to date, as well as the majority of satellites, have been in LEO, objects in LEO encounter atmospheric drag from gases in the thermosphere or exosphere, depending on orbit height. Due to atmospheric drag, satellites do not usually orbit below 300 km, objects in LEO orbit Earth between the denser part of the atmosphere and below the inner Van Allen radiation belt. The mean orbital velocity needed to maintain a stable low Earth orbit is about 7.8 km/s, calculated for circular orbit of 200 km it is 7.79 km/s and for 1500 km it is 7.12 km/s. The delta-v needed to achieve low Earth orbit starts around 9.4 km/s, atmospheric and gravity drag associated with launch typically adds 1. 3–1.8 km/s to the launch vehicle delta-v required to reach normal LEO orbital velocity of around 7.8 km/s. Equatorial low Earth orbits are a subset of LEO and these orbits, with low inclination to the Equator, allow rapid revisit times and have the lowest delta-v requirement of any orbit. Orbits with an inclination angle to the equator are usually called polar orbits. Higher orbits include medium Earth orbit, sometimes called intermediate circular orbit, orbits higher than low orbit can lead to early failure of electronic components due to intense radiation and charge accumulation. Although the Earths pull due to gravity in LEO is not much less than on the surface of the Earth, people, a low Earth orbit is simplest and cheapest for satellite placement. It provides high bandwidth and low communication time lag, but satellites in LEO will not be visible from any point on the Earth at all times. Earth observation satellites and spy satellites use LEO as they are able to see the surface of the Earth more clearly as they are not so far away and they are also able to traverse the surface of the Earth. A majority of satellites are placed in LEO, making one complete revolution around the Earth in about 90 minutes. The International Space Station is in a LEO about 400 km above the Earths surface, since it requires less energy to place a satellite into a LEO and the LEO satellite needs less powerful amplifiers for successful transmission, LEO is used for many communication applications. Because these LEO orbits are not geostationary, a network of satellites is required to provide continuous coverage, lower orbits also aid remote sensing satellites because of the added detail that can be gained. Remote sensing satellites can also take advantage of sun-synchronous LEO orbits at an altitude of about 800 km, envisat is one example of an Earth observation satellite that makes use of this particular type of LEO. The LEO environment is becoming congested with space debris due to the frequency of object launches and this has caused growing concern in recent years, since collisions at orbital velocities can easily be dangerous, and even deadly
Low earth orbit
–
This article needs additional citations for
verification. Please help improve this article by
adding citations to reliable sources. Unsourced material may be challenged and removed. (May 2012)
Low earth orbit
–
Comparison of
GPS,
GLONASS,
Galileo and
Compass (medium earth orbit) satellite navigation system orbits with the
International Space Station,
Hubble Space Telescope and
Iridium constellation orbits,
Geostationary Earth Orbit, and the nominal size of the
Earth. The
Moon 's orbit is around 9 times larger (in radius and length) than geostationary orbit.
24.
Van Allen radiation belt
–
A radiation belt is a zone of energetic charged particles, most of which originate from the solar wind that is captured by and held around a planet by that planets magnetic field. The Earth has two belts and sometimes others may be temporarily created. The discovery of the belts is credited to James Van Allen, Earths two main belts extend from an altitude of about 1,000 to 60,000 kilometers above the surface in which region radiation levels vary. Most of the particles form the belts are thought to come from solar wind. By trapping the solar wind, the magnetic field deflects those energetic particles, the belts are located in the inner region of the Earths magnetosphere. The belts trap energetic electrons and protons, other nuclei, such as alpha particles, are less prevalent. The belts endanger satellites, which must have their sensitive components protected with adequate shielding if they spend significant time in that zone, kristian Birkeland, Carl Størmer, and Nicholas Christofilos had investigated the possibility of trapped charged particles before the Space Age. Explorer 1 and Explorer 3 confirmed the existence of the belt in early 1958 under James Van Allen at the University of Iowa, the trapped radiation was first mapped by Explorer 4, Pioneer 3 and Luna 1. The term Van Allen belts refers specifically to the radiation belts surrounding Earth, however, the Sun does not support long-term radiation belts, as it lacks a stable, global, dipole field. The Earths atmosphere limits the belts particles to regions above 200–1,000 km, the belts are confined to a volume which extends about 65° on either side of the celestial equator. The NASA Van Allen Probes mission aims at understanding how populations of relativistic electrons and ions in space form or change in response to changes in solar activity, the Van Allen Probes mission successfully launched on August 30,2012. The primary mission is scheduled to last two years with expendables expected to last four, NASAs Goddard Space Flight Center manages the Living With a Star program of which the Van Allen Probes is a project, along with Solar Dynamics Observatory. The Applied Physics Laboratory is responsible for the implementation and instrument management for the Van Allen Probes, Radiation belts exist around other planets and moons in the solar system that have magnetic fields powerful enough to sustain them. To date, most of these belts have been poorly mapped. The Voyager Program only nominally confirmed the existence of similar belts around Uranus, the inner Van Allen Belt extends typically from an altitude of 0.2 to 2 Earth radii or 1,000 km to 6,000 km above the Earth. In certain cases when solar activity is stronger or in areas such as the South Atlantic Anomaly. The inner belt contains high concentrations of electrons in the range of hundreds of keV and energetic protons with energies exceeding 100 MeV, the source of lower energy protons is believed to be proton diffusion due to changes in the magnetic field during geomagnetic storms. Due to the offset of the belts from Earths geometric center
Van Allen radiation belt
–
Jupiter's variable radiation belts
Van Allen radiation belt
Van Allen radiation belt
–
Laboratory simulation of the Van Allen belt's influence on the Solar Wind; these aurora-like
Birkeland currents were created by the scientist
Kristian Birkeland in his
terrella, a magnetized anode globe in an evacuated chamber
Van Allen radiation belt
–
Cutaway drawing of two radiation belts around Earth: the inner belt (red) dominated by protons and the outer one (blue) by electrons. Image Credit: NASA
25.
Great Observatories program
–
NASAs series of Great Observatories satellites are four large, powerful space-based astronomical telescopes. Each of the four missions was designed to examine a specific region of the electromagnetic spectrum using very different technologies. Dr. Charles Pellerin, NASAs Director, Astrophysics invented and developed the program, the four Great Observatories were launched between 1990 and 2003, and three remain operational as of 2017. The Hubble Space Telescope primarily observes visible light and near-ultraviolet and it was launched in 1990 aboard Discovery during STS-31. A servicing mission in 1997 added capability in the range and one last mission in 2009 was to fix. The Compton Gamma Ray Observatory primarily observed gamma rays, though it extended into hard x-rays as well and it was launched in 1991 aboard Atlantis during STS-37 and was de-orbited in 2000 after failure of a gyroscope. The Chandra X-ray Observatory primarily observes soft x-rays and it was launched in 1999 aboard Columbia during STS-93 into an elliptical high-earth orbit, and was initially named the Advanced X-ray Astronomical Facility. The Spitzer Space Telescope observes the infrared spectrum and it was launched in 2003 aboard a Delta II rocket into an earth-trailing solar orbit, it was called the Space Infrared Telescope Facility before launch. Depletion of its liquid helium coolant in 2009 reduced its functionality significantly. Of these spacecraft, only the Compton Gamma Ray Observatory is not operating as of 2017, one of its gyroscopes failed, parts that survived reentry splashed into the Pacific Ocean. Hubble was originally intended to be retrieved and returned to Earth by the Space Shuttle, on October 31,2006 NASA Administrator Michael D. Griffin gave the go-ahead for a final refurbishment mission. Spitzer was the one of the Great Observatories not launched by the Space Shuttle. Titan and Atlas rockets were canceled for cost reasons, after redesign and lightening, it was launched by a Delta II rocket instead. The history of the Hubble Space Telescope can be traced back as far as 1946, Spitzer devoted much of his career to pushing for a space telescope to be developed. Congress eventually approved funding of US$36,000,000 for 1978, during the early 1980s, the telescope was named after Edwin Hubble. Gamma rays had been examined above the atmosphere by several early space missions, during its High Energy Astronomy Observatory Program in 1977, NASA announced plans to build a great observatory for gamma-ray astronomy. The Gamma Ray Observatory, renamed Compton Gamma-Ray Observatory, was designed to take advantage of the advances in detector technology during the 1980s. Following 14 years of effort, the CGRO was launched on 5 April 1991, in 1976 the Chandra X-ray Observatory was proposed to NASA by Riccardo Giacconi and Harvey Tananbaum
Great Observatories program
–
Four Great Observatories
Great Observatories program
–
Chandra, Hubble, and Spitzer image of the
Crab Nebula
Great Observatories program
–
IXO was considered as a possible future X-ray observatory
Great Observatories program
–
Calisto architecture for SAFIR was one concept for a future Far-infrared telescope
26.
Hubble Space Telescope
–
The Hubble Space Telescope is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. Although not the first space telescope, Hubble is one of the largest and most versatile, with a 2. 4-meter mirror, Hubbles four main instruments observe in the near ultraviolet, visible, and near infrared spectra. Hubbles orbit outside the distortion of Earths atmosphere allows it to take extremely high-resolution images, Hubble has recorded some of the most detailed visible light images ever, allowing a deep view into space and time. Many Hubble observations have led to breakthroughs in astrophysics, such as determining the rate of expansion of the universe. The HST was built by the United States space agency NASA, the Space Telescope Science Institute selects Hubbles targets and processes the resulting data, while the Goddard Space Flight Center controls the spacecraft. Space telescopes were proposed as early as 1923, Hubble was funded in the 1970s, with a proposed launch in 1983, but the project was beset by technical delays, budget problems, and the Challenger disaster. When finally launched in 1990, Hubbles main mirror was found to have been ground incorrectly, the optics were corrected to their intended quality by a servicing mission in 1993. Hubble is the telescope designed to be serviced in space by astronauts. After launch by Space Shuttle Discovery in 1990, five subsequent Space Shuttle missions repaired, upgraded, the fifth mission was canceled on safety grounds following the Columbia disaster. However, after spirited public discussion, NASA administrator Mike Griffin approved the fifth servicing mission, the telescope is operating as of 2017, and could last until 2030–2040. Its scientific successor, the James Webb Space Telescope, is scheduled for launch in 2018, the history of the Hubble Space Telescope can be traced back as far as 1946, to the astronomer Lyman Spitzers paper Astronomical advantages of an extraterrestrial observatory. In it, he discussed the two advantages that a space-based observatory would have over ground-based telescopes. First, the resolution would be limited only by diffraction, rather than by the turbulence in the atmosphere. Second, a telescope could observe infrared and ultraviolet light. Spitzer devoted much of his career to pushing for the development of a space telescope, space-based astronomy had begun on a very small scale following World War II, as scientists made use of developments that had taken place in rocket technology. An orbiting solar telescope was launched in 1962 by the United Kingdom as part of the Ariel space program, oAO-1s battery failed after three days, terminating the mission. It was followed by OAO-2, which carried out observations of stars and galaxies from its launch in 1968 until 1972. The continuing success of the OAO program encouraged increasingly strong consensus within the community that the LST should be a major goal
Hubble Space Telescope
–
The Hubble Space Telescope as seen from the departing
Space Shuttle Atlantis, flying Servicing Mission 4 (
STS-125), the fifth and final human spaceflight to it.
Hubble Space Telescope
–
Grinding of Hubble's primary mirror at Perkin-Elmer, March 1979
Hubble Space Telescope
–
The backup mirror, by Kodak; its inner support structure can be seen because it is not coated with a reflective surface.
Hubble Space Telescope
–
The OTA, metering truss, and secondary baffle are visible in this image of Hubble during early construction.
27.
Chandra X-ray Observatory
–
The Chandra X-ray Observatory, previously known as the Advanced X-ray Astrophysics Facility, is a Flagship-class space observatory launched on STS-93 by NASA on July 23,1999. Chandra is sensitive to X-ray sources 100 times fainter than any previous X-ray telescope, since the Earths atmosphere absorbs the vast majority of X-rays, they are not detectable from Earth-based telescopes, therefore space-based telescopes are required to make these observations. Chandra is an Earth satellite in a 64-hour orbit, and its mission is ongoing as of 2017, Chandra is one of the Great Observatories, along with the Hubble Space Telescope, Compton Gamma Ray Observatory, and the Spitzer Space Telescope. The telescope is named after astrophysicist Subrahmanyan Chandrasekhar, in 1976 the Chandra X-ray Observatory was proposed to NASA by Riccardo Giacconi and Harvey Tananbaum. Preliminary work began the year at Marshall Space Flight Center. In the meantime, in 1978, NASA launched the first imaging X-ray telescope, Einstein, work continued on the AXAF project throughout the 1980s and 1990s. In 1992, to reduce costs, the spacecraft was redesigned, four of the twelve planned mirrors were eliminated, as were two of the six scientific instruments. AXAFs planned orbit was changed to a one, reaching one third of the way to the Moons at its farthest point. This eliminated the possibility of improvement or repair by the space shuttle, AXAF was assembled and tested by TRW in Redondo Beach, California. AXAF was renamed Chandra as part of a contest held by NASA in 1998, the contest winners, Jatila van der Veen and Tyrel Johnson, suggested the name in honor of Nobel Prize–winning Indian-American astrophysicist Subrahmanyan Chandrasekhar. He is known for his work in determining the mass of white dwarf stars, leading to greater understanding of high energy astronomical phenomena such as neutron stars. Originally scheduled to be launched in December 1998, the spacecraft was delayed several months, Chandra has been returning data since the month after it launched. It is operated by the SAO at the Chandra X-ray Center in Cambridge, Massachusetts, with assistance from MIT, the ACIS CCDs suffered particle damage during early radiation belt passages. To prevent further damage, the instrument is now removed from the focal plane during passages. Although Chandra was initially given a lifetime of 5 years. Physically Chandra could last much longer, a study performed at the Chandra X-ray Center indicated that the observatory could last at least 15 years. In July 2008, the International X-ray Observatory, a joint project between ESA, NASA and JAXA, was proposed as the next major X-ray observatory but was later cancelled, ESA later resurrected the project as the Advanced Telescope for High Energy Astrophysics with a proposed launch in 2028. The data gathered by Chandra has greatly advanced the field of X-ray astronomy, in the Crab Nebula, another supernova remnant, Chandra showed a never-before-seen ring around the central pulsar and jets that had only been partially seen by earlier telescopes
Chandra X-ray Observatory
–
Illustration of Chandra
Chandra X-ray Observatory
–
STS-93 launches in 1999
Chandra X-ray Observatory
–
Crew of STS-93 with a scale model
Chandra X-ray Observatory
–
Chandra X-ray Observatory image of the brown dwarf TWA 5B.
28.
Spitzer Space Telescope
–
The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility, is an infrared space telescope launched in 2003. It is the fourth and final of the NASA Great Observatories program, the planned mission period was to be 2.5 years with a pre-launch expectation that the mission could extend to five or slightly more years until the onboard liquid helium supply was exhausted. This occurred on 15 May 2009, without liquid helium to cool the telescope to the very low temperatures needed to operate, most of the instruments are no longer usable. All Spitzer data, from both the primary and warm phases, are archived at the Infrared Science Archive, in keeping with NASA tradition, the telescope was renamed after its successful demonstration of operation, on 18 December 2003. Unlike most telescopes that are named after famous deceased astronomers by a board of scientists, the contest led to the telescope being named in honor of astronomer Lyman Spitzer, who had promoted the concept of space telescopes in the 1940s. Spitzer wrote a 1946 report for RAND Corporation describing the advantages of an extraterrestrial observatory, the US$720 million Spitzer was launched on 25 August 2003 at 05,35,39 UTC from Cape Canaveral SLC-17B aboard a Delta II 7920H rocket. It follows a heliocentric instead of orbit, trailing and drifting away from Earths orbit at approximately 0.1 astronomical unit per year. The primary mirror is 85 centimeters in diameter, f/12, made of beryllium and was cooled to 5.5 K, by the early 1970s, astronomers began to consider the possibility of placing an infrared telescope above the obscuring effects of Earths atmosphere. Anticipating the major results from an upcoming Explorer satellite and from the Shuttle mission, long-duration spaceflights of infrared telescopes cooled to cryogenic temperatures. Earlier infrared observations had been made by both space-based and ground-based observatories, ground-based observatories have the drawback that at infrared wavelengths or frequencies, both the Earths atmosphere and the telescope itself will radiate strongly. Additionally, the atmosphere is opaque at most infrared wavelengths and this necessitates lengthy exposure times and greatly decreases the ability to detect faint objects. It could be compared to trying to observe the stars at noon, previous space observatories were launched during the 1980s and 1990s and great advances in astronomical technology have been made since then. Most of the early concepts envisioned repeated flights aboard the NASA Space Shuttle and this approach was developed in an era when the Shuttle program was expected to support weekly flights of up to 30 days duration. A May 1983 NASA proposal described SIRTF as a Shuttle-attached mission, several flights were anticipated with a probable transition into a more extended mode of operation, possibly in association with a future space platform or space station. SIRTF would be a 1-meter class, cryogenically cooled, multi-user facility consisting of a telescope, the first flight was expected to occur about 1990, with the succeeding flights anticipated beginning approximately one year later. By September 1983 NASA was considering the possibility of a long duration SIRTF mission, Spitzer is the only one of the Great Observatories not launched by the Space Shuttle, as was originally intended. However, after the 1986 Challenger disaster, the Centaur LH2–LOX upper stage, the mission underwent a series of redesigns during the 1990s, primarily due to budget considerations. This resulted in a smaller but still fully capable mission that could use the smaller Delta II expendable launch vehicle
Spitzer Space Telescope
–
Artist rendering of the Spitzer Space Telescope
Spitzer Space Telescope
–
Spitzer in a Kennedy Space Center clean room
Spitzer Space Telescope
–
Asteroid
2011 MD seen by IRAC
Spitzer Space Telescope
–
SST images – 12th Anniversary (20 August 2015)
29.
Arthur Holly Compton
–
It was a sensational discovery at the time, the wave nature of light had been well-demonstrated, but the idea that light had both wave and particle properties was not easily accepted. He is also known for his leadership of the Manhattan Projects Metallurgical Laboratory, in 1919, Compton was awarded one of the first two National Research Council Fellowships that allowed students to study abroad. He chose to go to Cambridge Universitys Cavendish Laboratory in England, further research along these lines led to the discovery of the Compton effect. During World War II, Compton was a key figure in the Manhattan Project that developed the first nuclear weapons and his reports were important in launching the project. Compton oversaw Enrico Fermis creation of Chicago Pile-1, the first nuclear reactor, the Metallurgical Laboratory was also responsible for the design and operation of the X-10 Graphite Reactor at Oak Ridge, Tennessee. Plutonium began being produced in the Hanford Site reactors in 1945, after the war, Compton became Chancellor of Washington University in St. Louis. Arthur Compton was born on September 10,1892, in Wooster, Ohio, the son of Elias and Otelia Catherine Compton, Elias was dean of the University of Wooster, which Arthur also attended. Arthurs eldest brother, Karl, who also attended Wooster, earned a PhD in physics from Princeton University in 1912, all three brothers were members of the Alpha Tau Omega fraternity. Compton was initially interested in astronomy, and took a photograph of Halleys Comet in 1910, around 1913, he described an experiment where an examination of the motion of water in a circular tube demonstrated the rotation of the earth. That year, he graduated from Wooster with a Bachelor of Science degree and entered Princeton, where he received his Master of Arts degree in 1914. Compton then studied for his PhD in physics under the supervision of Hereward L. Cooke, writing his dissertation on The intensity of X-ray reflection, and the distribution of the electrons in atoms. When Arthur Compton earned his PhD in 1916, he, Karl, later, they would become the first such trio to simultaneously head American colleges. Their sister Mary married a missionary, C. Herbert Rice, in June 1916, Compton married Betty Charity McCloskey, a Wooster classmate and fellow graduate. They had two sons, Arthur Alan and John Joseph Compton, during World War I he developed aircraft instrumentation for the Signal Corps. In 1919, Compton was awarded one of the first two National Research Council Fellowships that allowed students to study abroad and he chose to go to Cambridge Universitys Cavendish Laboratory in England. Working with George Paget Thomson, the son of J. J. Thomson, Compton studied the scattering and he observed that the scattered rays were more easily absorbed than the original source. Compton was greatly impressed by the Cavendish scientists, especially Ernest Rutherford, Charles Galton Darwin and Arthur Eddington, for a time Compton was a deacon at a Baptist church. Science can have no quarrel, he said, with a religion which postulates a God to whom men are as His children
Arthur Holly Compton
–
Arthur Compton in 1927
Arthur Holly Compton
–
Arthur Compton and
Werner Heisenberg in 1929 in Chicago
Arthur Holly Compton
–
Arthur Holly Compton on the cover of Time Magazine on January 13, 1936, holding his cosmic ray detector
Arthur Holly Compton
–
Compton at the University of Chicago in 1933 with graduate student
Luis Alvarez next to his cosmic ray telescope.
30.
Washington University in St. Louis
–
Washington University in St. Louis is a private research university located in St. Louis, Missouri, United States. Founded in 1853, and named after George Washington, the university has students and faculty from all 50 U. S. states, twenty-five Nobel laureates have been affiliated with Washington University, nine having done the major part of their pioneering research at the university. Washington Universitys undergraduate program is ranked 19th by U. S. News & World Report, the university is ranked 23rd in the world in 2016 by the Academic Ranking of World Universities. Washington University is made up of seven graduate and undergraduate schools that encompass a range of academic fields. To prevent confusion over its location, the Board of Trustees added the phrase in St. Louis in 1976, Washington University was conceived by 17 St. Louis business, political, and religious leaders concerned by the lack of institutions of higher learning in the Midwest. Missouri State Senator Wayman Crow and Unitarian minister William Greenleaf Eliot, grandfather of the poet T. S. Eliot, the universitys first chancellor was Joseph Gibson Hoyt. Crow secured the university charter from the Missouri General Assembly in 1853, early on, Eliot solicited support from members of the local business community, including John OFallon, but Eliot failed to secure a permanent endowment. Washington University is unusual among major American universities in not having had a financial endowment. The institution had no backing of an organization, single wealthy patron. During the three following its inception, the university bore three different names. In 1854, the Board of Trustees changed the name to Washington Institute in honor of George Washington, naming the University after the nations first president, only seven years before the American Civil War and during a time of bitter national division, was no coincidence. During this time of conflict, Americans universally admired George Washington as the father of the United States, the Board of Trustees believed that the university should be a force of unity in a strongly divided Missouri. In 1856, the University amended its name to Washington University, although chartered as a university, for many years Washington University functioned primarily as a night school located on 17th Street and Washington Avenue in the heart of downtown St. Louis. Owing to limited resources, Washington University initially used public buildings. Classes began on October 22,1854, at the Benton School building, at first the university paid for the evening classes, but as their popularity grew, their funding was transferred to the St. Louis Public Schools. Eventually the board secured funds for the construction of Academic Hall, later the university divided into three departments, the Manual Training School, Smith Academy, and the Mary Institute. In 1867, the university opened the first private law school west of the Mississippi River. By 1882, Washington University had expanded to numerous departments, which were housed in buildings across St. Louis
Washington University in St. Louis
–
William Greenleaf Eliot, first president of the Board of Trustees
Washington University in St. Louis
–
Washington University in St. Louis
Washington University in St. Louis
–
The Washington University crest at the entrance to
Francis Field
Washington University in St. Louis
–
Brookings Hall Quad
31.
Northrop Grumman
–
Northrop Grumman Corporation is an American global aerospace and defense technology company formed by Northrops 1994 purchase of Grumman. The company was named as the fifth-largest defense contractor in the world in 2015, Northrop Grumman employs over 68,000 people worldwide. It reported revenues of $23.526 billion in 2015, Northrop Grumman ranks No.124 on the 2015 Fortune 500 list of Americas largest corporations and ranks in the top ten military-friendly employers. It is headquartered in West Falls Church, Virginia, Northrop Grumman is made up of three business sectors, Aerospace Systems, Mission Systems, and Technology Services. Aerospace Systems, headquartered in Redondo Beach, California produces aircraft, spacecraft, high-energy laser systems and microelectronics for the US and other nations. The B-2 Spirit strategic bomber, the E-8C Joint STARS surveillance aircraft, the RQ-4 Global Hawk, the US Army uses Northrop Grummans RQ-5 Hunter unmanned air vehicle, which has been in operational use since 1995. The U. S. Navy uses Northrop Grumman-built aerial vehicles such as the BQM-74 Chukar, RQ-4 Global Hawk based BAMS UAS, Grumman C-2 Greyhound, Grumman E-2 Hawkeye, and the EA-6B Prowler. Northrop Grumman provides major components and assemblies for different aircraft such as F/A-18 Hornet, F/A-18E/F Super Hornet, Electronic Systems produces and maintains the AWACS aerial surveillance systems for the U. S. the United Kingdom, NATO, Japan, and others. Northrop Grumman is the contractor for the development and integration of the Air Forces $2-billion Multi-Platform Radar Technology Insertion Program. Many other smaller products are made by Northrop Grumman, such as night vision goggles, information Systems, headquartered in McLean, Virginia, supports the U. S. Vinnell, a Technical Services Northrop Grumman subsidiary, provides training and communications for the military. In 2003, it landed a $48 million contract to train the Iraqi Army, in 2005 the company won a $2 billion contract with Virginia to overhaul most of the states IT operations. Later that year, The United Kingdom paid $1.2 billion in a contract with the company to provide maintenance of the countrys defensive radar, Northrop Grumman performs various functions in the War on Drugs. The company sends planes to spray herbicides on suspected cocaine fields in Colombia, remotec, a subsidiary, is the foremost manufacturer of remote control vehicles for explosive ordnance disposal and hazardous material handling. A UK-based subsidiary, Park Air Systems, provides VHF and UHF ground-to-air communications systems for the civil, Northrop Grumman has also worked closely with Antenna Associates, Inc. a manufacturer of Identification friend or foe /Secondary Surveillance Radar antennas located in Massachusetts. In August 2007, Northrop Grumman acquired Scaled Composites in which it had owned a 40% stake. Originally formed in California in 1939 by Jack Northrop, the Northrop Corporation was reincorporated in Delaware in 1985, in 1994, Northrop Aircraft bought Grumman Aerospace, famous for building the Apollo Lunar Module to create Northrop Grumman. In 1996, the new company acquired Westinghouse Electronic Systems, a manufacturer of radar systems. In 1997, the defense computer contractor Logicon was added, which had acquired Geodynamics Corporation in March 1996, in 1998, a merger between Northrop Grumman and competitor Lockheed Martin was considered but abandoned after resistance from the Department of Defense and Department of Justice
Northrop Grumman
–
Northrop Grumman manufactured the
B-2 Spirit strategic bomber.
Northrop Grumman
–
A
BQM-74 Chukar unmanned aerial drone launches from a
US Navy vessel
Northrop Grumman
–
The
assembly line for
Northrop P-61 Black Widows at the Northrop plant in
Hawthorne, California in World War II. Center wings and fuselages take shape on the left, with more nearly finished complete ships on the right.
Northrop Grumman
–
Rendering of the $8.7B James Webb Space Telescope
32.
Redondo Beach, California
–
Redondo Beach is one of the three Beach Cities located in Los Angeles County, California, United States. The population was 66,748 at the 2010 census, up from 63,261 at the 2000 census, the city is located in the South Bay region of the greater Los Angeles area. Redondo Beach was originally part of the 1785 Rancho San Pedro Spanish land grant that became the South Redondo area. The citys territory has an unusual shape including an area along the beach and another strip inland from Manhattan Beach, the primary attractions include Municipal Pier and the sandy beach, popular with tourists and a variety of sports enthusiasts. The western terminus of the Metro Rail Green Line is in North Redondo Beach, the Chowigna Indians used the site of todays Hopkins Wilderness Park, formerly Nike missile site LA-57 from 1956 to 1963, in Redondo Beach, California, as a lookout place. The wetlands located at the site of todays AES power plant in Redondo Beach were a source of foods including halibut, lobster, and sea bass, and also of salt. In the 1700s, the Chowigna bartered salt from the old Redondo Salt Lake and their village by the lake was called Onoova-nga, or Place of Salt. The Chowigna were relocated to missions in 1854, when Manuel Dominguez sold 215 acres of Rancho San Pedro, including the lake, to Henry Allanson, moonstone Beach was a tourist attraction from the late 1880s to the early 1920s. Tourists gathered moonstones from the mounds that had washed ashore during storms. According to the United States Census Bureau, the city has an area of 6.2 square miles. Redondo Beach was originally part of the 1784 Rancho San Pedro Spanish land grant of the 43, the ocean side of Pacific Coast Highway has restaurants and boating activities while inland of PCH is largely residential. Redondo Breakwall is a surf spot in the South Bay. This power plant sports Whaling Wall number 31, a 586 ft ×95 ft whale mural by world-famous artist Robert Wyland titled Gray Whale Migration. Redondo Beach has a division between the north and south sections of the city with 190th, Anita, and Herondo streets forming its east-west boundary line. South Redondo is along the beachfront with the pier and marina/harbor complex, the small business district near the pier and marina was revived in the 1990s by beachgoers and new residents who wanted to sell beachwear and surfing accessories. South Redondo has wide streets, wide beaches and laid-back feel make it a prime destination for those seeking a bike to the grocery store community. The main library is located in the Civic Center, North Redondo, north of 190th Street, is an inland community separated from the beachfront by Hermosa Beach and Manhattan Beach. It is also home to the South Bay Galleria shopping center, the North Branch of the Redondo Beach Library serves this area
Redondo Beach, California
–
Redondo Beach - King Harbor sign
Redondo Beach, California
–
Redondo Beach, 1906
Redondo Beach, California
–
South Bay Galleria, a shopping mall on the border of Lawndale
Redondo Beach, California
–
Redondo Beach Pier
33.
California
–
California is the most populous state in the United States and the third most extensive by area. Located on the western coast of the U. S, California is bordered by the other U. S. states of Oregon, Nevada, and Arizona and shares an international border with the Mexican state of Baja California. Los Angeles is Californias most populous city, and the second largest after New York City. The Los Angeles Area and the San Francisco Bay Area are the nations second- and fifth-most populous urban regions, California also has the nations most populous county, Los Angeles County, and its largest county by area, San Bernardino County. The Central Valley, an agricultural area, dominates the states center. What is now California was first settled by various Native American tribes before being explored by a number of European expeditions during the 16th and 17th centuries, the Spanish Empire then claimed it as part of Alta California in their New Spain colony. The area became a part of Mexico in 1821 following its war for independence. The western portion of Alta California then was organized as the State of California, the California Gold Rush starting in 1848 led to dramatic social and demographic changes, with large-scale emigration from the east and abroad with an accompanying economic boom. If it were a country, California would be the 6th largest economy in the world, fifty-eight percent of the states economy is centered on finance, government, real estate services, technology, and professional, scientific and technical business services. Although it accounts for only 1.5 percent of the states economy, the story of Calafia is recorded in a 1510 work The Adventures of Esplandián, written as a sequel to Amadis de Gaula by Spanish adventure writer Garci Rodríguez de Montalvo. The kingdom of Queen Calafia, according to Montalvo, was said to be a land inhabited by griffins and other strange beasts. This conventional wisdom that California was an island, with maps drawn to reflect this belief, shortened forms of the states name include CA, Cal. Calif. and US-CA. Settled by successive waves of arrivals during the last 10,000 years, various estimates of the native population range from 100,000 to 300,000. The Indigenous peoples of California included more than 70 distinct groups of Native Americans, ranging from large, settled populations living on the coast to groups in the interior. California groups also were diverse in their organization with bands, tribes, villages. Trade, intermarriage and military alliances fostered many social and economic relationships among the diverse groups, the first European effort to explore the coast as far north as the Russian River was a Spanish sailing expedition, led by Portuguese captain Juan Rodríguez Cabrillo, in 1542. Some 37 years later English explorer Francis Drake also explored and claimed a portion of the California coast in 1579. Spanish traders made unintended visits with the Manila galleons on their trips from the Philippines beginning in 1565
California
–
A forest of redwood trees in
Redwood National Park
California
–
Flag
California
–
Mount Shasta
California
–
Aerial view of the
California Central Valley
34.
European Space Agency
–
The European Space Agency is an intergovernmental organisation of 22 member states, dedicated to the exploration of space. Established in 1975 and headquartered in Paris, France, ESA has a staff of about 2,000. The main European launch vehicle Ariane 5 is operated through Arianespace with ESA sharing in the costs of launching, after World War II, many European scientists left Western Europe in order to work with the United States. The meeting was attended by representatives from eight countries, including Harrie Massey. The Western European nations decided to have two different agencies, one concerned with developing a system, ELDO, and the precursor of the European Space Agency. The latter was established on 20 March 1964 by an agreement signed on 14 June 1962, from 1968 to 1972, ESRO launched seven research satellites. ESA in its current form was founded with the ESA Convention in 1975, ESA has 10 founding member states, Belgium, Denmark, France, Germany, Italy, the Netherlands, Spain, Sweden, Switzerland and the United Kingdom. These signed the ESA Convention in 1975 and deposited the instruments of ratification by 1980, during this interval the agency functioned in a de facto fashion. ESA launched its first major scientific mission in 1975, Cos-B, ESA joined NASA in the IUE, the worlds first high-orbit telescope, which was launched in 1978 and operated very successfully for 18 years. A number of successful Earth-orbit projects followed, and in 1986 ESA began Giotto, its first deep-space mission, to study the comets Halley and Grigg–Skjellerup. Hipparcos, a mission, was launched in 1989 and in the 1990s SOHO, Ulysses. Recent scientific missions in co-operation with NASA include the Cassini–Huygens space probe, as the successor of ELDO, ESA has also constructed rockets for scientific and commercial payloads. Ariane 1, launched in 1979, brought mostly commercial payloads into orbit from 1984 onward, the successor launch vehicle of Ariane 5, the Ariane 6 is already in the definition stage and is envisioned to enter service in the 2020s. The beginning of the new millennium saw ESA become, along with agencies like NASA, JAXA, ISRO, CSA and Roscosmos, one of the major participants in scientific space research. Although ESA had relied on co-operation with NASA in previous decades, especially the 1990s, changed circumstances led to decisions to rely more on itself, a 2011 press issue thus stated, Russia is ESAs first partner in its efforts to ensure long-term access to space. ESA maintains its scientific and research projects mainly for astronomy-space missions such as Corot, launched on 27 December 2006 and this is the reason space exploration is an integral part of overall space activities. It has always been so, and it will be more important in the future. ESA describes its work in two overlapping ways, For the general public the various fields of work are described as Activities, Member states participate to varying degrees in the mandatory and optional space programmes
European Space Agency
–
ESA Mission Control at
ESOC in
Darmstadt, Germany
European Space Agency
–
Acronym
European Space Agency
–
ESTEC buildings in
Noordwijk, Netherlands. ESTEC was the main technical centre of ESRO and remains so for the successor organization, ESA.
European Space Agency
–
Mock-up of the
Ariane 1
35.
Naval Research Laboratory
–
A few of the laboratorys current specialties include plasma physics, space physics, materials science, and tactical electronic warfare. NRL is one of the first US Government scientific R&D laboratories, having opened in 1923 at the instigation of Thomas Edison, NRLs research expenditures are approximately $1.1 billion per year. The Naval Research Laboratory conducts a variety of basic and scientific research. It has a history of scientific breakthroughs and technological achievements dating back to its foundation in 1923. In many instances the contributions to military technology are declassified decades after those technologies have become widely adopted. In 2011, NRL researchers published 1,398 unclassified scientific & technical articles, book chapters, in 2008, the NRL was ranked #3 among all U. S. institutions holding nanotechnology-related patents, behind IBM and the University of California. The laboratory houses a range of R&D facilities. The most recent additions include the NRL Nanoscience Institutes 5000sqft Class 100 nanofabrication cleanroom and quiet measurement labs, the Naval Research Laboratory has been a crucial piece of the United States space program. Project Vanguard, the first American satellite program, tasked NRL with the design, construction and launch of an artificial satellite, Vanguard I, designed and built at NRL, was the first solar-powered satellite. As of 2013, Vanguard I is still in orbit, making it the longest-lived man-made satellite, Vanguard II was the first satellite to observe the Earths cloud cover and therefore the first meteorological satellite. NRL pioneered the study of the sun Ultraviolet and X-Ray spectrum, along with Project Vanguard, NRL also designed the first satellite tracking system, Minitrack, which became the prototype for future satellite tracking networks. NRLs recently declassified Galactic Radiation and Background I was the first U. S. intelligence satellite, NRLs spacecraft development program continues today with the TacSat-4 experimental tactical reconnaissance & communication satellite. In addition to design, NRL also designs and operates research instruments, such as the Large Angle and Spectrometric Coronagraph Experiment aboard the Solar. NASAs Gamma-ray Large Area Space Telescope was tested at NRL spacecraft testing facilities, NRL scientists have most recently contributed leading research to the study of novas and gamma ray bursts. Modern mechanical fracture mechanics were pioneered at NRL and were applied to solve fracture problems in Navy vessels, commercial aircraft. That knowledge is in use today in applications ranging from design of nuclear reactors to aircraft, submarines. NRLs GaAs inventions were licensed by Rockwell, Westinghouse, Texas Instruments, high-purity GaAs is also used for high-efficiency solar cells like those aboard NASAs Spirit and Opportunity rovers currently on Mars. Fundamental aspects of technology were developed at NRL, including the radar absorption mechanisms in ferrite-containing materials
Naval Research Laboratory
–
Part of the Naval Research Laboratory main campus in Washington, DC. The prominent satellite dish is often used as a symbol of the laboratory.
Naval Research Laboratory
–
Emblem of the NRL
Naval Research Laboratory
–
This building on NRL's main campus features prominent
radomes on its roof.
Naval Research Laboratory
–
Part of the NRL complex seen from the air above the
Potomac River in 2012. The part of the campus shown contains the oldest five buildings on the campus.
36.
INTEGRAL
–
In mathematics, an integral assigns numbers to functions in a way that can describe displacement, area, volume, and other concepts that arise by combining infinitesimal data. Integration is one of the two operations of calculus, with its inverse, differentiation, being the other. The area above the x-axis adds to the total and that below the x-axis subtracts from the total, roughly speaking, the operation of integration is the reverse of differentiation. For this reason, the integral may also refer to the related notion of the antiderivative. In this case, it is called an integral and is written. The integrals discussed in this article are those termed definite integrals, a rigorous mathematical definition of the integral was given by Bernhard Riemann. It is based on a procedure which approximates the area of a curvilinear region by breaking the region into thin vertical slabs. A line integral is defined for functions of two or three variables, and the interval of integration is replaced by a curve connecting two points on the plane or in the space. In a surface integral, the curve is replaced by a piece of a surface in the three-dimensional space and this method was further developed and employed by Archimedes in the 3rd century BC and used to calculate areas for parabolas and an approximation to the area of a circle. A similar method was developed in China around the 3rd century AD by Liu Hui. This method was used in the 5th century by Chinese father-and-son mathematicians Zu Chongzhi. The next significant advances in integral calculus did not begin to appear until the 17th century, further steps were made in the early 17th century by Barrow and Torricelli, who provided the first hints of a connection between integration and differentiation. Barrow provided the first proof of the theorem of calculus. Wallis generalized Cavalieris method, computing integrals of x to a power, including negative powers. The major advance in integration came in the 17th century with the independent discovery of the theorem of calculus by Newton. The theorem demonstrates a connection between integration and differentiation and this connection, combined with the comparative ease of differentiation, can be exploited to calculate integrals. In particular, the theorem of calculus allows one to solve a much broader class of problems. Equal in importance is the mathematical framework that both Newton and Leibniz developed
INTEGRAL
–
A definite integral of a function can be represented as the signed area of the region bounded by its graph.
37.
Swift Gamma-Ray Burst Mission
–
The Swift Gamma-Ray Burst Mission consists of a robotic spacecraft called Swift, which was launched into orbit on November 20,2004, at 17,16,00 UTC on a Delta II 7320-10C expendable launch vehicle. It is part of NASAs Medium Explorer program, the mission is operated at Pennsylvania State University. Swift is a space observatory dedicated to the study of gamma-ray bursts. Its three instruments work together to observe GRBs and their afterglows in the gamma-ray, X-ray, ultraviolet, based on continuous scans of the area of the sky with one of the instruments monitors, Swift uses momentum wheels to autonomously slew into the direction of possible GRBs. The name Swift is not an acronym, but rather a reference to the instruments rapid slew capability. All of Swifts discoveries are transmitted to the ground and those data are available to other observatories which join Swift in observing the GRBs. In the time between GRB events, Swift is available for scientific investigations, and scientists from universities. The Swift main ground station is located at the Broglio Space Centre near Malindi on the coast of Eastern Kenya, the Swift Science Data Center and archive are located at the Goddard Space Flight Center outside Washington D. C. The UK Swift Science Data Centre is located at the University of Leicester, the Swift spacecraft bus was built by Spectrum Astro, which was later acquired by General Dynamics Advanced Information Systems, which was in turn acquired by Orbital Sciences Corporation. The BAT detects GRB events and computes its coordinates in the sky and it covers a large fraction of the sky. It locates the position of each event with an accuracy of 1 to 4 arc-minutes within 15 seconds and this crude position is immediately relayed to the ground, and some wide-field, rapid-slew ground-based telescopes can catch the GRB with this information. The BAT uses a mask of 52,000 randomly placed 5 mm lead tiles,1 metre above a detector plane of 32,768 four mm CdZnTe hard X-ray detector tiles. The XRT can take images and perform spectral analysis of the GRB afterglow and this provides more precise location of the GRB, with a typical error circle of approximately 2 arcseconds radius. The XRT is also used to perform monitoring of GRB afterglow light-curves for days to weeks after the event. The XRT uses a Wolter Type I X-ray telescope with 12 nested mirrors, on-board software allows fully automated observations, with the instrument selecting an appropriate observing mode for each object, based on its measured count rate. The telescope has a range of 0.2 -10 keV. After Swift has slewed towards a GRB, the UVOT is used to detect an optical afterglow, the UVOT provides a sub-arcsecond position and provides optical and ultra-violet photometry through lenticular filters and low resolution spectra through the use of its optical and UV grisms. The UVOT is also used to provide long-term follow-ups of GRB afterglow lightcurves, the UVOT is based on the XMM-Newton missions Optical Monitor instrument, with improved optics and upgraded onboard processing computers
Swift Gamma-Ray Burst Mission
–
UVOT's "
first light " picture.
Swift Gamma-Ray Burst Mission
–
Swift Gamma-Ray Burst Mission
38.
Fermi Gamma-ray Space Telescope
–
The Fermi Gamma-ray Space Telescope, formerly called the Gamma-ray Large Area Space Telescope, is a space observatory being used to perform gamma-ray astronomy observations from low Earth orbit. Another instrument aboard Fermi, the Gamma-ray Burst Monitor, is being used to study gamma-ray bursts, Fermi was launched on 11 June 2008 at 16,05 UTC aboard a Delta II 7920-H rocket. The mission is a joint venture of NASA, the United States Department of Energy, and government agencies in France, Germany, Italy, Japan, Fermi includes two scientific instruments, the Large Area Telescope and the Gamma-ray Burst Monitor. The GBM consists of 14 scintillation detectors, and can detect gamma-ray bursts in that range across the whole of the sky not occluded by the Earth. General Dynamics Advanced Information Systems in Gilbert, Arizona designed and built the spacecraft that carries the instruments and it travels in a low, circular orbit with a period of about 95 minutes. Its normal mode of operation maintains its orientation so that the instruments will look away from the Earth, with a motion to equalize the coverage of the sky. The view of the instruments will sweep out across most of the sky about 16 times per day, the spacecraft can also maintain an orientation that points to a chosen target. They were integrated with the spacecraft at the General Dynamics ASCENT facility in Gilbert, data from the instruments are available to the public through the Fermi Science Support Center web site. Software for analyzing the data is also available, Fermi gained its new name in 2008, On 26 August 2008, GLAST was renamed the Fermi Gamma-ray Space Telescope in honor of Enrico Fermi, a pioneer in high-energy physics. Something memorable to commemorate this spectacular new astronomy mission, a name that is catchy, easy to say and will help make the satellite and its mission a topic of dinner table and classroom discussion. NASA designed the mission with a lifetime, with a goal of ten years of operations. The key scientific objectives of the Fermi mission have been described as, To understand the mechanisms of particle acceleration in active galactic nuclei, pulsars, resolve the gamma-ray sky, unidentified sources and diffuse emission. Determine the high-energy behavior of gamma-ray bursts and transients, probe dark matter and early Universe. Search for evaporating primordial black holes from their presumed gamma burst signatures. The National Academies of Sciences ranked this mission as a top priority, many new possibilities and discoveries are anticipated to emerge from this single mission and greatly expand our view of the Universe. Gamma-ray bursts Study gamma-ray bursts with an energy range several times more intense than ever before so that scientists may be able to understand them better, neutron stars Study younger, more energetic pulsars in the Milky Way than ever before so as to broaden our understanding of stars. Study the pulsed emissions of magnetospheres so as to possibly solve how they are produced, Study how pulsars generate winds of interstellar particles. Milky Way galaxy Provide new data to improve upon existing theoretical models of our own galaxy
Fermi Gamma-ray Space Telescope
–
Fermi Gamma-ray Space Telescope
Fermi Gamma-ray Space Telescope
Fermi Gamma-ray Space Telescope
–
Fermi on Earth, solar arrays folded
Fermi Gamma-ray Space Telescope
–
The GLAST spacecraft after arriving at Cape Canaveral in May 2008
39.
Electromagnetic spectrum
–
The electromagnetic spectrum is the collective term for all known frequencies and their linked wavelengths of the known photons. The electromagnetic spectrum of an object has a different meaning, and is instead the characteristic distribution of radiation emitted or absorbed by that particular object. Visible light lies toward the end, with wavelengths from 400 to 700 nanometres. The limit for long wavelengths is the size of the universe itself, until the middle of the 20th century it was believed by most physicists that this spectrum was infinite and continuous. Nearly all types of radiation can be used for spectroscopy, to study. Other technological uses are described under electromagnetic radiation, for most of history, visible light was the only known part of the electromagnetic spectrum. The ancient Greeks recognized that light traveled in straight lines and studied some of its properties, the study of light continued, and during the 16th and 17th centuries conflicting theories regarded light as either a wave or a particle. The first discovery of electromagnetic radiation other than visible light came in 1800 and he was studying the temperature of different colors by moving a thermometer through light split by a prism. He noticed that the highest temperature was beyond red and he theorized that this temperature change was due to calorific rays that were a type of light ray that could not be seen. The next year, Johann Ritter, working at the end of the spectrum. These behaved similarly to visible light rays, but were beyond them in the spectrum. They were later renamed ultraviolet radiation, during the 1860s James Maxwell developed four partial differential equations for the electromagnetic field. Two of these equations predicted the possibility of, and behavior of, analyzing the speed of these theoretical waves, Maxwell realized that they must travel at a speed that was about the known speed of light. This startling coincidence in value led Maxwell to make the inference that light itself is a type of electromagnetic wave, maxwells equations predicted an infinite number of frequencies of electromagnetic waves, all traveling at the speed of light. This was the first indication of the existence of the electromagnetic spectrum. Maxwells predicted waves included waves at very low compared to infrared. Hertz found the waves and was able to infer that they traveled at the speed of light, Hertz also demonstrated that the new radiation could be both reflected and refracted by various dielectric media, in the same manner as light. For example, Hertz was able to focus the waves using a lens made of tree resin, in a later experiment, Hertz similarly produced and measured the properties of microwaves
Electromagnetic spectrum
–
The electromagnetic spectrum
40.
Marshall Space Flight Center
–
The George C. Marshall Space Flight Center is the U. S. governments civilian rocketry and spacecraft propulsion research center. The largest NASA center, MSFCs first mission was developing the Saturn launch vehicles for the Apollo moon program, located on the Redstone Arsenal near Huntsville, Alabama, MSFC is named in honor of General of the Army George Marshall. The center also contains the Huntsville Operations Support Center, a facility that supports ISS launch, payload, the HOSC also monitors rocket launches from Cape Canaveral Air Force Station when a Marshall Center payload is on board. The largest and best-known activity was called Operation Paperclip, in August 1945,127 missile specialists led by Wernher von Braun signed work contracts with the U. S. Armys Ordnance Corps. Most of them had worked on the V-2 missile development under von Braun at Peenemünde, Von Braun and the other Germans were sent to Fort Bliss, Texas, joining the Armys newly formed Research and Development Division Sub-office. Von Braun had long had a great interest in rocketry for space science, toward this, he was allowed to use a WAC Corporal rocket as a second stage for a V-2, the combination, called Bumper, reached a record-breaking 250 miles altitude. During World War II, the production and storage of shells was conducted by three arsenals nearby to Huntsville, Alabama. After the war, these were closed, and the three areas were combined to form Redstone Arsenal, a year later, the Secretary of the Army approved the transfer of the rocket research and development activities from Fort Bliss to the new center at Redstone Arsenal. Beginning in April 1950, about 1,000 persons were involved in the transfer, at this time, R&D responsibility for guided missiles was added, and studies began on a medium-range guided missile that eventually became the Redstone rocket. Over the next decade, the development on Redstone Arsenal greatly expanded. Many small free-flight and guided rockets were developed, and work on the Redstone rocket got underway, although this rocket was primarily intended for military purposes, von Braun kept space firmly in his mind, and published a widely read article on this subject. In mid-1952, the Germans who had worked under individual contracts were converted to civil service employees. Von Braun was appointed Chief of the Guided Missile Development Division, in September 1954, von Braun proposed using the Redstone as the main booster of a multi-stage rocket for launching artificial satellites. A year later, a study for Project Orbiter was completed, detailing plans, the Armys official role in the U. S. space satellite program was delayed, however, after higher authorities elected to use the Vanguard rocket then being developed by the Naval Research Laboratory. In February 1956, the Army Ballistic Missile Agency was established, von Braun was the director of the Development Operations Division. One of the programs was a 1, 500-mile, single-stage missile that was started the previous year. The first Jupiter IRBM flight took place from Cape Canaveral in March 1957 with the first successful flight to full range on 31 May, Jupiter was eventually taken over by the U. S. Air Force. The ABMA developed Jupiter-C was composed of a Redstone rocket first stage, while the Jupiter C capability was such that it could have placed the fourth stage in orbit, that mission had been assigned to the NRL
Marshall Space Flight Center
–
Aerial view of the test area at MSFC
Marshall Space Flight Center
–
Ceremony of transfer from Army to NASA July 1, 1960
Marshall Space Flight Center
–
Rockets developed at MSFC and ABMA before it are on display at MSFC.
Marshall Space Flight Center
–
A crane hoists
Space Shuttle Pathfinder into the Saturn V Dynamic Test Stand at MSFC to test the procedures in preparation for the dynamic test of
Space Shuttle Enterprise.
41.
Gamma ray burst
–
In gamma-ray astronomy, Gamma-ray bursts are extremely energetic explosions that have been observed in distant galaxies. They are the brightest electromagnetic events known to occur in the universe, Bursts can last from ten milliseconds to several hours. After an initial flash of gamma rays, a longer-lived afterglow is usually emitted at longer wavelengths, a subclass of GRBs appear to originate from a different process, the merger of binary neutron stars. The sources of most GRBs are billions of years away from Earth. All observed GRBs have originated from outside the Milky Way galaxy, although a class of phenomena. It has been hypothesized that a gamma-ray burst in the Milky Way, pointing directly towards the Earth, GRBs were first detected in 1967 by the Vela satellites, which had been designed to detect covert nuclear weapons tests. Following their discovery, hundreds of models were proposed to explain these bursts. These discoveries, and subsequent studies of the galaxies and supernovae associated with the bursts, clarified the distance and luminosity of GRBs, definitively placing them in distant galaxies. Gamma-ray bursts were first observed in the late 1960s by the U. S. Vela satellites, the United States suspected that the USSR might attempt to conduct secret nuclear tests after signing the Nuclear Test Ban Treaty in 1963. On July 2,1967, at 14,19 UTC, uncertain what had happened but not considering the matter particularly urgent, the team at the Los Alamos Scientific Laboratory, led by Ray Klebesadel, filed the data away for investigation. As additional Vela satellites were launched with better instruments, the Los Alamos team continued to find inexplicable gamma-ray bursts in their data, the discovery was declassified and published in 1973. Most early theories of gamma-ray bursts posited nearby sources within the Milky Way Galaxy, if the sources were from within our own galaxy they would be strongly concentrated in or near the galactic plane. The absence of any pattern in the case of GRBs provided strong evidence that gamma-ray bursts must come from beyond the Milky Way. However, some Milky Way models are consistent with an isotropic distribution. For decades after the discovery of GRBs, astronomers searched for a counterpart at other wavelengths, astronomers considered many distinct classes of objects, including white dwarfs, pulsars, supernovae, globular clusters, quasars, Seyfert galaxies, and BL Lac objects. This suggested an origin of either very faint stars or extremely distant galaxies and this fading emission would be called the afterglow. Early searches for this afterglow were unsuccessful, largely because it is difficult to observe a bursts position at longer wavelengths immediately after the initial burst, the William Herschel Telescope identified a fading optical counterpart 20 hours after the burst. Once the GRB faded, deep imaging was able to identify a faint, distant host galaxy at the location of the GRB as pinpointed by the optical afterglow, because of the very faint luminosity of this galaxy, its exact distance was not measured for several years
Gamma ray burst
–
Artist's illustration showing the life of a
massive star as
nuclear fusion converts lighter elements into heavier ones. When fusion no longer generates enough pressure to counteract gravity, the star rapidly collapses to form a
black hole. Theoretically, energy may be released during the collapse along the axis of rotation to form a gamma-ray burst.
Gamma ray burst
–
Positions on the sky of all gamma-ray bursts detected during the BATSE mission. The distribution is
isotropic, with no concentration towards the plane of the Milky Way, which runs horizontally through the center of the image.
Gamma ray burst
–
The Italian–Dutch satellite
BeppoSAX, launched in April 1996, provided the first accurate positions of gamma-ray bursts, allowing follow-up observations and identification of the sources.
Gamma ray burst
–
NASA 's
Swift Spacecraft launched in November 2004
42.
Gamma spectroscopy
–
Gamma-ray spectroscopy is the quantitative study of the energy spectra of gamma-ray sources, in such as the nuclear industry, geochemical investigation, and astrophysics. Most radioactive sources produce gamma rays, which are of various energies and intensities, when these emissions are detected and analyzed with a spectroscopy system, a gamma-ray energy spectrum can be produced. A detailed analysis of spectrum is typically used to determine the identity and quantity of gamma emitters present in a gamma source. Gamma rays are the form of electromagnetic radiation, being physically the same as all other forms. Because of this, the energy of photons can be resolved individually. Radioactive nuclei commonly emit gamma rays in the range from a few keV to ~10 MeV. Such sources typically produce gamma-ray line spectra, whereas much higher energies may occur in the continuum spectra observed in astrophysics, other components, such as rate meters and peak position stabilizers, may also be included. The most common detectors include sodium iodide scintillation counters and high-purity germanium detectors, gamma spectroscopy detectors are passive materials that wait for a gamma interaction to occur in the detector volume. The most important interaction mechanisms are the effect, the Compton effect. The photoelectric effect is preferred, as it all of the energy of the incident gamma ray. Full energy absorption is also possible when a series of these interaction mechanisms take place within the detector volume and this count will appear in a channel below the channel that corresponds to the full energy of the gamma ray. Larger detector volumes reduce this effect, the voltage pulse produced by the detector is shaped by a multichannel analyzer. The multichannel analyzer takes the very small voltage signal produced by the detector, reshapes it into a Gaussian or trapezoidal shape, in some systems, the analog-to-digital conversion is performed before the peak is reshaped. The analog-to-digital converter also sorts the pulses by their height, aDCs have specific numbers of bins into which the pulses can be sorted, these bins represent the channels in the spectrum. The number of channels can be changed in most modern gamma spectroscopy systems by modifying software or hardware settings, the number of channels is typically a power of two, common values include 512,1024,2048,4096,8192, or 16384 channels. The choice of number of channels depends on the resolution of the system, the multichannel analyzer output is sent to a computer, which stores, displays, and analyzes the data. Gamma spectroscopy systems are selected to take advantage of performance characteristics. Two of the most important include detector resolution and detector efficiency, gamma rays detected in a spectroscopic system produce peaks in the spectrum
Gamma spectroscopy
–
The gamma-ray spectrum of natural
uranium, showing about a dozen discrete lines superimposed on a smooth continuum, allows the identification the
nuclides 226Ra,
214Pb, and
214Bi of the uranium
decay chain.
Gamma spectroscopy
–
Laboratory equipment for determination of γ-radiation spectrum with a scintillation counter. The output from the scintillation counter goes to a Multichannel Analyser which processes and formats the data.
Gamma spectroscopy
–
Figure 2: Sodium iodide gamma spectrum of cobalt-60 (60 Co)
Gamma spectroscopy
–
Germanium gamma spectrum of a radioactive Am-Be-source.
43.
Telemetry
–
Telemetry is an automated communications process by which measurements and other data are collected at remote or inaccessible points and transmitted to receiving equipment for monitoring. The word is derived from Greek roots, tele = remote, systems that need external instructions and data to operate require the counterpart of telemetry, telecommand. Many modern telemetry systems take advantage of the low cost and ubiquity of GSM networks by using SMS to receive, a telemeter is a device used to remotely measure any quantity. It consists of a sensor, a path, and a display, recording. Telemeters are the devices used in telemetry. Electronic devices are used in telemetry and can be wireless or hard-wired. Other technologies are possible, such as mechanical, hydraulic. Telemetry may be commutated to allow the transmission of data streams in a fixed frame. Telemetering information over wire had its origins in the 19th century, One of the first data-transmission circuits was developed in 1845 between the Russian Tsars Winter Palace and army headquarters. In 1874, French engineers built a system of weather and snow-depth sensors on Mont Blanc that transmitted real-time information to Paris, in 1901 the American inventor C. Michalke patented the selsyn, a circuit for sending synchronized rotation information over a distance, in 1906 a set of seismic stations were built with telemetering to the Pulkovo Observatory in Russia. In 1912, Commonwealth Edison developed a system of telemetry to monitor electrical loads on its power grid, the Panama Canal used extensive telemetry systems to monitor locks and water levels. Wireless telemetry made early appearances in the radiosonde, developed concurrently in 1930 by Robert Bureau in France, mochanovs system modulated temperature and pressure measurements by converting them to wireless Morse code. In the US and the USSR, the Messina system was replaced with better systems. Early Soviet missile and space telemetry systems which were developed in the late 1940s used either pulse-position modulation or pulse-duration modulation, in the United States, early work employed similar systems, but were later replaced by pulse-code modulation. Later Soviet interplanetary probes used redundant radio systems, transmitting telemetry by PCM on a decimeter band, telemetry has been used by weather balloons for transmitting meteorological data since 1920. Telemetry is used to transmit drilling mechanics and formation evaluation information uphole, in real time and these services are known as Measurement while drilling and Logging while drilling. Information acquired thousands of feet below ground, while drilling, is sent through the hole to the surface sensors
Telemetry
–
An expendable
dropsonde used to capture weather data. The telemetry consists of sensors for pressure, temperature, and humidity and a wireless transmitter to return the captured data to an aircraft.
Telemetry
–
A
saltwater crocodile with a GPS-based satellite transmitter attached to its head for tracking
44.
Caesium iodide
–
Caesium iodide is the ionic compound of caesium and iodine. It is often used as the input phosphor of an image intensifier tube found in fluoroscopy equipment. Caesium iodide photocathodes are highly efficient at extreme ultraviolet wavelengths, an important application of caesium iodide crystals, which are scintillators, is electromagnetic calorimetry in experimental particle physics. Pure CsI is a fast and dense scintillating material with high light yield. It shows two main components, one in the near ultraviolet region at the wavelength of 310 nm. The drawbacks of CsI are a temperature gradient and a slight hygroscopicity. Caesium iodide is used as a beamsplitter in Fourier transform infrared spectrometers and it has a wider transmission range than the more common potassium bromide beamsplitters, extending its working range into the far infrared. However, optical-quality CsI crystals are very soft and a hard to cleave or polish and they should also be coated and stored in a desiccator, to minimize interaction with atmospheric water vapors. Caesium iodide atomic chains can be grown inside carbon nanotubes. Accurate measurements reveal that in such chains I atoms appear brighter than Cs atoms despite having a smaller mass and this difference was explained by the charge difference between Cs atoms, inner nanotube walls and I atoms. As a result, Cs atoms are attracted to the walls and vibrate more strongly than I atoms, which are pushed toward the nanotube axis
Caesium iodide
–
Monoatomic caesium halide wires grown inside double-wall
carbon nanotubes.
Caesium iodide
–
Cesium iodide
45.
Photomultiplier tube
–
Elements of photomultiplier technology, when integrated differently, are the basis of night vision devices. Research that analyzes light scattering, such as the study of polymers in solution use a laser. Photomultipliers are typically constructed with an evacuated glass housing, containing a photocathode, several dynodes, incident photons strike the photocathode material, which is usually a thin vapor-deposited conducting layer on the inside of the entry window of the device. Electrons are ejected from the surface as a consequence of the photoelectric effect and these electrons are directed by the focusing electrode toward the electron multiplier, where electrons are multiplied by the process of secondary emission. The electron multiplier consists of a number of electrodes called dynodes, each dynode is held at a more positive potential, by ≈100 Volts, than the preceding one. A primary electron leaves the photocathode with the energy of the photon, or about 3 eV for blue photons. A small group of primary electrons is created by the arrival of a group of initial photons, the primary electrons move toward the first dynode because they are accelerated by the electric field. They each arrive with ≈100 eV kinetic energy imparted by the potential difference, upon striking the first dynode, more low energy electrons are emitted, and these electrons are in turn accelerated toward the second dynode. The geometry of the chain is such that a cascade occurs with an exponentially-increasing number of electrons being produced at each stage. This last stage is called the anode, the necessary distribution of voltage along the series of dynodes is created by a voltage divider chain, as illustrated in the Figure. In the example, the photocathode is held at a high voltage of order 1000V. The capacitors across the final few dynodes act as reservoirs of charge to help maintain the voltage on the dynodes while electron avalanches propagate through the tube. Many variations of design are used in practice, the design shown is merely illustrative, the side-on design is used, for instance, in the type 931, the first mass-produced PMT. Besides the different photocathode materials, performance is affected by the transmission of the window material that the light passes through. A large number of models are available having various combinations of these. Either of the manuals mentioned will provide the information needed to choose a design for a particular application. The invention of the photomultiplier is predicated upon two prior achievements, the discoveries of the photoelectric effect and of secondary emission. The first demonstration of the effect was carried out in 1887 by Heinrich Hertz using ultraviolet light
Photomultiplier tube
–
Photomultiplier
Photomultiplier tube
–
Dynodes inside a photomultiplier tube
Photomultiplier tube
–
Schematic of a photomultiplier tube coupled to a
scintillator. This arrangement is for detection of gamma rays.
Photomultiplier tube
–
Typical photomultiplier voltage divider circuit using negative high voltage.
46.
Electronic anticoincidence
–
But the desired events are mixed up with a significant number of other events, produced by other particles or other processes, which create indistinguishable events in the detector. An early example of such a system, first proposed by Kenneth John Frost in 1962, is shown in the figure. A plastic scintillator may be used across the front which is transparent to gamma rays. The effect is to minimize the Compton edge feature in the data, since the detectors are so small, it is likely that the gamma ray will Compton scatter out of the detector before it deposits all of its energy. In this case, the reading by the data acquisition system will come up short. In order to counteract this, the expensive and small high resolution detector is surrounded by larger and cheaper low resolution detectors, usually sodium iodide scintillators. The much larger suppression detector has much more stopping power than the main detector, modern experiments in nuclear and high-energy particle physics almost invariably use fast anticoincidence circuits to veto unwanted events. Nuclear electronics HEAO1 HEAO3 INTEGRAL Uhuru Gamma-ray spectroscopy Compton Suppression
Electronic anticoincidence
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Drawing of an active anticoincidence collimated scintillation spectrometer designed for gamma-ray astronomy in the energy range from 0.1 to 3 MeV.
47.
Max Planck Institute for Extraterrestrial Physics
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The Max Planck Institute for Extraterrestrial Physics is a Max Planck Institute, located in Garching, near Munich, Germany. The Max Planck Institute for Extraterrestrial Physics was founded as sub-institute in 1963, the scientific activities of the institute are mostly devoted to astrophysics with telescopes orbiting in space. A large amount of the resources are spent for studying black holes in the galaxy, the Max-Planck-Institute for extraterrestrial physics was preceded by the department for extraterrestrial physics in the Max-Planck-Institute for physics and astrophysics. This department was established by Professor Reimar Lüst on October 23,1961, a Max-Planck Senate resolution transformed this department into a sub-institute of the Max-Planck-Institute for Physics and Astrophysics on May 15,1963. Professor Lüst was appointed director of the Institute, another Senate resolution on March 8,1991 finally established MPE as an autonomous institute within the Max-Planck-Gesellschaft. It is dedicated to the experimental and theoretical exploration of the space outside of earth as well as astrophysical phenomena, the former independent X-ray and Gamma-ray departments are merged into the new high-energy astrophysics department. This department was established by Professor Reimar Lüst on October 23,1961, a Max-Planck Senate resolution transformed this department into a sub-institute of the Max-Planck-Institut für Physik und Astrophysik on May 15,1963. Professor Lüst was appointed Director of the Institute, another Senate resolution on March 8,1991 finally established MPE as an autonomous institute within the Max-Planck-Gesellschaft. It is dedicated to the experimental and theoretical exploration of the space outside of earth as well as astrophysical phenomena, a continuous reorientation to new, promising fields of research and the appointment of new members ensures steady advancement. Among the 29 employees of the Institute when it was founded in 1963 were 9 scientists and 1 Ph. D. student. Twelve years later in 1975 the number of employees had grown to 180 with 55 scientists and 13 Ph. D. students and it is noteworthy that permanent positions at the institute have not increased since 1973 - despite its celebrated scientific achievements. The increasingly complex tasks and international obligations have been maintained by staff members with positions having limited duration. Because the Institute has assumed a position in astronomy internationally. The number of guests increased from 12 in 1974 to a maximum of 72 in 2000. In recent years MPE has hosted an average of about 50 guest scientists each year, during the early years the scientific work at the Institute concentrated on the investigation of extraterrestrial plasmas and the magnetosphere of the earth. This work was performed with measurements of particles and electromagnetic fields as well as a specially developed ion-cloud technique using sounding rockets and these observations and inferences therefrom are the subject matter of infra-red astronomy as well as X-ray- and gamma-ray-astronomy. In addition to more than 100 rockets, a number of high-altitude balloons have been used to carry experiments to high altitudes. Since the 1990s, satellites have become the preferred observation platforms because of their favorable observation-time/cost ratio, nevertheless, high-flying observation airplanes and ground-based telescopes are also used to obtain data especially for optical and near-infrared observations
Max Planck Institute for Extraterrestrial Physics
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Agreement Signed for MICADO Camera for
E-ELT.
48.
University of New Hampshire
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The University of New Hampshire is a public research university in the University System of New Hampshire, in the United States. The universitys Durham campus, comprising six colleges, is located in the Seacoast region of the state, a seventh college, the University of New Hampshire at Manchester, occupies the universitys campus in Manchester, the states largest city. The University of New Hampshire School of Law, known as the Franklin Pierce Law Center until 2010, is located in Concord, the University of New Hampshire was founded and incorporated in 1866, as a land grant college in Hanover in connection with Dartmouth College. In 1893, UNH moved to Durham, with over 15,000 students between its Durham, Manchester, and Concord campuses, UNH is the largest university in the state. The university is one of only nine land, sea and space grant institutions in the nation, since July 1,2007, Mark W. Huddleston has served as the universitys 19th president. The Morrill Act of 1862 granted federal lands to New Hampshire for the establishment of an agricultural-mechanical college, in 1866, the university was first incorporated as the New Hampshire College of Agriculture and the Mechanic Arts in Hanover, New Hampshire, in association with Dartmouth College. The institution was officially associated with Dartmouth College and was directed by Dartmouths president, Durham resident Benjamin Thompson left his farm and assets to the state for the establishment of an agricultural college. On January 30,1890, Benjamin Thompson died and his will became public, on March 5,1891 Gov. Hiram Americus Tuttle signed an act accepting the conditions of Thompsons will. On April 10,1891, Gov. Tuttle signed a bill authorizing the colleges move to Durham, New Hampshire. In 1892, the Board of Trustees hired Charles Eliot to draw a plan for the first five campus buildings, Thompson, Conant, Nesmith, and Hewitt Shops. Eliot visited Durham and worked for three months to create a plan prior to the move to Durham, the Class of 1892, excited about the pending move to Durham, held commencement exercises in an unfinished barn on the Durham campus. On April 18,1892, the Board of Trustees voted to authorize the faculty to all the arrangements for the packing. In fall 1893, classes began in Durham with 51 freshmen and 13 upperclassmen. Graduate study was established in fall 1893 for the first time. The number of students and the lack of funds for dormitories caused a housing crunch. The lack of housing caused difficulty for attracting women to the university, in 1908, construction on Smith Hall, the first womens dorm, was completed using private and state funds. Prior to the construction of Fairchild Hall in 1915 for male students,50 freshmen lived in the basement of DeMerritt Hall, with the continuing housing shortage for men, the administration encouraged the growth of the UNH Greek system. From the late 1910s through the 1930s, the fraternity system expanded and provided room, in 1923, Gov. Fred Herbert Brown signed a bill changing the name of the college to University of New Hampshire
University of New Hampshire
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Thompson Hall, built in 1892, is listed on the
National Register of Historic Places
University of New Hampshire
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University of New Hampshire
University of New Hampshire
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Morrill Hall c. 1920
University of New Hampshire
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Pettee Hall c. 2005
49.
Netherlands Institute for Space Research
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SRON Netherlands Institute for Space Research is the Dutch expertise institute for space research. The Institute develops and uses innovative technology for research in space, focusing on research, Earth science. SRON has a line of research into new and more sensitive sensors for X-rays, SRON was founded in 1983 under the former names Stichting Ruimteonderzoek Nederland / Space Research Organisation Netherlands. SRON is part of the Netherlands Organisation for Scientific Research and has facilities in Utrecht, sRON’s ambition is to act as leading institute in the development of state-of-the-art satellite instruments for space research missions of ESA, NASA and other agencies. Examples of future missions to which SRON will contribute are SPICA, ASTRO-H, the institute is also planning contributions to missions which will study other planets in the Solar System and beyond. This requires longterm investments in the development of new sensors, electronics, in the near future detectors shall increasingly take the shape of large chips with many megapixels, with a unique combination of two dimensional pictures and spectroscopy color resolving power. These detectors require the development of new advanced electronics, smart control software, extreme cooling techniques, SRON develops a new generation of detectors, and the necessary read-out and control electronics, for international missions in the submillimeter and far-infrared areas. For example, such extremely sensitive detectors are needed in SPICA/ SAFARI so that we can learn more about protoplanetary discs, for SPICA/ SAFARI SRON is currently working on Transition Edge Sensors. Customers are on the one hand the international organizations with which SRON cooperates in bilateral, on the other hand, there is science as the customer, scientists from the Universities in Utrecht, Groningen and Leiden, and outside the Dutch borders for example with DLR. Johan Bleeker Karel Wakker Roel Gathier Rens Waters List of space telescopes Official website SRON
Netherlands Institute for Space Research
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SRON Netherlands Institute for Space Research Ruimteonderzoeksinstituut SRON
Netherlands Institute for Space Research
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SRON, Utrecht, Netherlands
Netherlands Institute for Space Research
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Optical photograph of a bolometer for SAFARI (detail); the shiny square is the superconducting TES thermometer, the large grey square is the Ta absorber. The ring-type structure is the SiN suspension, intended to produce a very weak coupling to the heat bath and thus a sensitive detector.
50.
Steradian
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The steradian or square radian is the SI unit of solid angle. It is used in geometry, and is analogous to the radian which quantifies planar angles. The name is derived from the Greek stereos for solid and the Latin radius for ray and it is useful, however, to distinguish between dimensionless quantities of a different nature, so the symbol sr is used to indicate a solid angle. For example, radiant intensity can be measured in watts per steradian, the steradian was formerly an SI supplementary unit, but this category was abolished in 1995 and the steradian is now considered an SI derived unit. A steradian can be defined as the angle subtended at the center of a unit sphere by a unit area on its surface. For a general sphere of radius r, any portion of its surface with area A = r2 subtends one steradian, because the surface area A of a sphere is 4πr2, the definition implies that a sphere measures 4π steradians. By the same argument, the solid angle that can be subtended at any point is 4π sr. Since A = r2, it corresponds to the area of a cap. Therefore one steradian corresponds to the angle of the cross-section of a simple cone subtending the plane angle 2θ, with θ given by, θ = arccos = arccos = arccos ≈0.572 rad. This angle corresponds to the plane angle of 2θ ≈1.144 rad or 65. 54°. A steradian is also equal to the area of a polygon having an angle excess of 1 radian, to 1/4π of a complete sphere. The solid angle of a cone whose cross-section subtends the angle 2θ is, Ω =2 π s r. In two dimensions, an angle is related to the length of the arc that it spans, θ = l r r a d where l is arc length, r is the radius of the circle. For example, a measurement of the width of an object would be given in radians. At the same time its visible area over ones visible field would be given in steradians. Just as the area of a circle is related to its diameter or radius. One-dimensional circular measure has units of radians or degrees, while two-dimensional spherical measure is expressed in steradians, in higher dimensional mathematical spaces, units for analogous solid angles have not been explicitly named. When they are used, they are dealt with by analogy with the circular or spherical cases and that is, as a proportion of the relevant unit hypersphere taken up by the generalized angle, or point set expressed in spherical coordinates
Steradian
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A graphical representation of 1 steradian. The sphere has radius r, and in this case the area A of the highlighted surface patch is r 2. The solid angle Ω equals A sr/ r 2 which is 1 sr in this example. The entire sphere has a solid angle of 4π sr.
