Hubble Space Telescope
The Hubble Space Telescope is a space telescope, 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 and is well known as both a vital research tool and a public relations boon for astronomy; the HST is named after the astronomer Edwin Hubble and is one of NASA's Great Observatories, along with the Compton Gamma Ray Observatory, the Chandra X-ray Observatory and the Spitzer Space Telescope. With a 2.4-meter mirror, Hubble's four main instruments observe in the ultraviolet and near infrared regions of the electromagnetic spectrum. Hubble's orbit outside the distortion of Earth's atmosphere allows it to take high-resolution images, with lower background light than ground-based telescopes. Hubble has recorded some of the most detailed visible light images 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, with contributions from the European Space Agency. The Space Telescope Science Institute selects Hubble's 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, the Challenger disaster; when launched in 1990, Hubble's main mirror was found to have been ground incorrectly, creating a spherical aberration, compromising the telescope's capabilities. The optics were corrected to their intended quality by a servicing mission in 1993. Hubble is the only telescope designed to be serviced in space by astronauts. After launch by Space Shuttle Discovery in 1990, five subsequent Space Shuttle missions repaired and replaced systems on the telescope, including all five of the main instruments; 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, completed in 2009. The telescope is operating as of 2019, could last until 2030–2040. After numerous delays, its successor, the James Webb Space Telescope, is scheduled to be launched in March 2021. In 1923, Hermann Oberth—considered a father of modern rocketry, along with Robert H. Goddard and Konstantin Tsiolkovsky—published Die Rakete zu den Planetenräumen, which mentioned how a telescope could be propelled into Earth orbit by a rocket; the history of the Hubble Space Telescope can be traced back as far as 1946, to the astronomer Lyman Spitzer's paper "Astronomical advantages of an extraterrestrial observatory". In it, he discussed the two main advantages that a space-based observatory would have over ground-based telescopes. First, the angular resolution would be limited only by diffraction, rather than by the turbulence in the atmosphere, which causes stars to twinkle, known to astronomers as seeing.
At that time ground-based telescopes were limited to resolutions of 0.5–1.0 arcseconds, compared to a theoretical diffraction-limited resolution of about 0.05 arcsec for a telescope with a mirror 2.5 m in diameter. Second, a space-based telescope could observe infrared and ultraviolet light, which are absorbed by the atmosphere. Spitzer devoted much of his career to pushing for the development of a space telescope. In 1962, a report by the US National Academy of Sciences recommended the development of a space telescope as part of the space program, in 1965 Spitzer was appointed as head of a committee given the task of defining scientific objectives for a large space telescope. Space-based astronomy had begun on a small scale following World War II, as scientists made use of developments that had taken place in rocket technology; the first ultraviolet spectrum of the Sun was obtained in 1946, the National Aeronautics and Space Administration launched the Orbiting Solar Observatory to obtain UV, X-ray, gamma-ray spectra in 1962.
An orbiting solar telescope was launched in 1962 by the United Kingdom as part of the Ariel space program, in 1966 NASA launched the first Orbiting Astronomical Observatory mission. OAO-1's battery failed after three days, it was followed by OAO-2, which carried out ultraviolet observations of stars and galaxies from its launch in 1968 until 1972, well beyond its original planned lifetime of one year. The OSO and OAO missions demonstrated the important role space-based observations could play in astronomy, in 1968, NASA developed firm plans for a space-based reflecting telescope with a mirror 3 m in diameter, known provisionally as the Large Orbiting Telescope or Large Space Telescope, with a launch slated for 1979; these plans emphasized the need for manned maintenance missions to the telescope to ensure such a costly program had a lengthy working life, the concurrent development of plans for the reusable Space Shuttle indicated that the technology to allow this was soon to become available.
The continuing success of the OAO program encouraged strong consensus within the astronomical community that the LST should be a major goal. In 1970, NASA established two committees, one to plan the engineering side of the space telescope project, the other to determine the scientific goals of the mission. Once these had been established, the next hurdle for NASA was to obtain funding for the instrument, which would be far more costly than any Earth-bas
Gamma ray
A gamma ray or gamma radiation, is a penetrating electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves and so imparts the highest 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 based on their strong penetration of matter. Gamma rays from radioactive decay are in the energy range from a few keV to ~8 MeV, corresponding to the typical energy levels in nuclei with reasonably long lifetimes; the energy spectrum of gamma rays can be used to identify the decaying radionuclides using gamma spectroscopy. Very-high-energy gamma rays in the 100–1000 TeV range have been observed from sources such as the Cygnus X-3 microquasar. Natural sources of gamma rays originating on Earth are as a result of radioactive decay and secondary radiation from atmospheric interactions with cosmic ray particles.
However there are other rare natural sources, such as terrestrial gamma-ray flashes, that produce gamma rays from electron action upon the nucleus. Notable artificial sources of gamma rays include fission, such as occurs in nuclear reactors, as well as high energy physics experiments, such as neutral pion decay and nuclear fusion. Gamma rays and X-rays are both electromagnetic radiation and they overlap in the electromagnetic spectrum, the terminology varies between scientific disciplines. In some fields of physics, they are distinguished by their origin: Gamma rays are created by nuclear decay, while in the case of X-rays, the origin is outside the nucleus. In astrophysics, gamma rays are conventionally defined as having photon energies above 100 keV and are the subject of gamma ray astronomy, while radiation below 100 keV is classified as X-rays and is the subject of X-ray astronomy; this convention stems from the early man-made X-rays, which had energies only up to 100 keV, whereas many gamma rays could go to higher energies.
A large fraction of astronomical gamma rays are screened by Earth's atmosphere. Gamma rays are thus biologically hazardous. Due to their high penetration power, they can damage internal organs. Unlike alpha and beta rays, they pass through the body and thus pose a formidable radiation protection challenge, requiring shielding made from dense materials such as lead or concrete; the first gamma ray source to be discovered was the radioactive decay process called gamma decay. In this type of decay, an excited nucleus emits a gamma ray immediately upon formation. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900, while studying radiation emitted from radium. Villard knew that his described radiation was more powerful than described types of rays from radium, which included beta rays, first noted as "radioactivity" by Henri Becquerel in 1896, alpha rays, discovered as a less penetrating form of radiation by Rutherford, in 1899. However, Villard did not consider naming them as a different fundamental type.
In 1903, Villard's radiation was recognized as being of a type fundamentally different from named rays by Ernest Rutherford, who named Villard's rays "gamma rays" by analogy with the beta and alpha rays that Rutherford had differentiated in 1899. The "rays" emitted by radioactive elements were named in order of their power to penetrate various materials, using the first three letters of the Greek alphabet: alpha rays as the least penetrating, followed by beta rays, followed by gamma rays as the most penetrating. Rutherford noted that gamma rays were not deflected by a magnetic field, another property making them unlike alpha and beta rays. Gamma rays were first thought to be particles like alpha and beta rays. Rutherford believed that they might be 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, proving that they were electromagnetic radiation. Rutherford and his co-worker Edward Andrade measured the wavelengths of gamma rays from radium, found that they were similar to X-rays, but with shorter wavelengths and higher frequency.
This was recognized as giving them more energy per photon, as soon as the latter term became accepted. A gamma decay was understood to emit a gamma photon. Natural sources of gamma rays on Earth include gamma decay from occurring radioisotopes such as potassium-40, as a secondary radiation from various atmospheric interactions with cosmic ray particles; some rare terrestrial natural sources that produce gamma rays that are not of a nuclear origin, are lightning strikes and terrestrial gamma-ray flashes, which produce high energy emissions from natural high-energy voltages. Gamma rays are produced by a number of astronomical processes in which high-energy electrons are produced; such electrons produce secondary gamma rays by the mechanisms of bremsstrahlung, inverse Compton scattering and synchrotron radiation. A large fraction of such astronomical gamma rays are screened by Earth's atmosphere. Notable artificial sources of gamma rays include fission, such as occurs in nuclear reactors, as well as high energy physics experiments, such as neutral pion decay and nuclear fusion.
A sample of gamma ray-emitting material, used for irradiating or imaging is known as a gamma source. It is called a radioactive sou
Gamma-ray burst
In gamma-ray astronomy, gamma-ray bursts are 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 emitted at longer wavelengths; the intense radiation of most observed GRBs is thought to be released during a supernova or superluminous supernova as a high-mass star implodes to form a neutron star or a black hole. A subclass of GRBs appear to originate from a kilonova; the cause of the precursor burst observed in some of these short events may be the development of a resonance between the crust and core of such stars as a result of the massive tidal forces experienced in the seconds leading up to their collision, causing the entire crust of the star to shatter. The sources of most GRBs are billions of light years away from Earth, implying that the explosions are both energetic and rare.
All observed GRBs have originated from outside the Milky Way galaxy, although a related class of phenomena, soft gamma repeater flares, are associated with magnetars within the Milky Way. It has been hypothesized that a gamma-ray burst in the Milky Way, pointing directly towards the Earth, could cause a mass extinction event. GRBs were first detected in 1967 by the Vela satellites, designed to detect covert nuclear weapons tests. Following their discovery, hundreds of theoretical models were proposed to explain these bursts, such as collisions between comets and neutron stars. Little information was available to verify these models until the 1997 detection of the first X-ray and optical afterglows and direct measurement of their redshifts using optical spectroscopy, thus their distances and energy outputs; these discoveries, 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, which were built to detect gamma radiation pulses emitted by nuclear weapons tested in space; the United States suspected that the Soviet Union might attempt to conduct secret nuclear tests after signing the Nuclear Test Ban Treaty in 1963. On July 2, 1967, at 14:19 UTC, the Vela 4 and Vela 3 satellites detected a flash of gamma radiation unlike any known nuclear weapons signature. Uncertain what had happened but not considering the matter urgent, the team at the Los Alamos National 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. By analyzing the different arrival times of the bursts as detected by different satellites, the team was able to determine rough estimates for the sky positions of sixteen bursts and definitively rule out a terrestrial or solar origin.
The discovery was declassified and published in 1973. Most early theories of gamma-ray bursts posited nearby sources within the Milky Way Galaxy. From 1991, the Compton Gamma Ray Observatory and its Burst and Transient Source Explorer instrument, an sensitive gamma-ray detector, provided data that showed the distribution of GRBs is isotropic—not biased towards any particular direction in space. If the sources were from within our own galaxy they would be concentrated in or near the galactic plane; the absence of any such 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 still consistent with an isotropic distribution. In October 2018, astronomers reported that GRB 150101B, a gamma-ray burst event detected in 2015, may be directly related to the historic GW170817, a gravitational wave event detected in 2017, associated with the merger of two neutron stars; the similarities between the two events, in terms of gamma ray, optical and x-ray emissions, as well as to the nature of the associated host galaxies, are "striking", suggesting the two separate events may both be the result of the merger of neutron stars, both may be a kilonova, which may be more common in the universe than understood, according to the researchers.
For decades after the discovery of GRBs, astronomers searched for a counterpart at other wavelengths: i.e. any astronomical object in positional coincidence with a observed burst. Astronomers considered many distinct classes of objects, including white dwarfs, supernovae, globular clusters, Seyfert galaxies, BL Lac objects. All such searches were unsuccessful, in a few cases well-localized bursts could be shown to have no bright objects of any nature consistent with the position derived from the detecting satellites; this suggested an origin of either faint stars or distant galaxies. The most accurate positions contained numerous faint stars and galaxies, it was agreed that final resolution of the origins of cosmic gamma-ray bursts would require both new satellites and faster communication. Several models for the origin of gamma-ray bursts postulated that the initial burst of gamma rays should be followed by fading emission at longer wavelengths created by collisions betwee
Washington University in St. Louis
Washington University in St. Louis is a private research university in St. Louis, Missouri. Founded in 1853, named after George Washington, the university has students and faculty from all 50 U. S. states and more than 120 countries. As of 2017, 24 Nobel laureates in economics and medicine, physics have been affiliated with Washington University, nine having done the major part of their pioneering research at the university. Washington University's undergraduate program is ranked 19th by U. S. News & World Report in 2018 and 11th by The Wall Street Journal in their 2018 rankings; the university is ranked 20th in the world in 2018 by the Academic Ranking of World Universities. The acceptance rate for the class of 2023 was 14%, with students selected from more than 31,000 applications. Of students admitted 90 percent were in the top 10 percent of their class. Washington University is made up of seven graduate and undergraduate schools that encompass a broad 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 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, led the effort; the university's first chancellor was Joseph Gibson Hoyt. Crow secured the university charter from the Missouri General Assembly in 1853, Eliot was named President of the Board of Trustees. Early on, Eliot solicited support from members of the local business community, including John O'Fallon, but Eliot failed to secure a permanent endowment. Washington University is unusual among major American universities in not having had a prior financial endowment; the institution had no backing of a religious organization, single wealthy patron, or earmarked government support. During the three years following its inception, the university bore three different names; the board first approved "Eliot Seminary," but William Eliot was uncomfortable with naming a university after himself and objected to the establishment of a seminary, which would implicitly be charged with teaching a religious faith.
He favored a nonsectarian university. In 1854, the Board of Trustees changed the name to "Washington Institute" in honor of George Washington. Naming the University after the nation's 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 and a symbol of national unity; the Board of Trustees believed that the university should be a force of unity in a divided Missouri. In 1856, the University amended its name to "Washington University." The university amended its name once more in 1976, when the Board of Trustees voted to add the suffix "in St. Louis" to distinguish the university from the nearly two dozen other universities bearing Washington's name. Although chartered as a university, for many years Washington University functioned as a night school located on 17th Street and Washington Avenue in the heart of downtown St. Louis.
Owing to limited financial resources, Washington University used public buildings. Classes began on October 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; the board secured funds for the construction of Academic Hall and a half dozen other buildings. The university divided into three departments: the Manual Training School, Smith Academy, the Mary Institute. In 1867, the university opened the first private nonsectarian law school west of the Mississippi River. By 1882, Washington University had expanded to numerous departments, which were housed in various buildings across St. Louis. Medical classes were first held at Washington University in 1891 after the St. Louis Medical College decided to affiliate with the University, establishing the School of Medicine. During the 1890s, Robert Sommers Brookings, the president of the Board of Trustees, undertook the tasks of reorganizing the university's finances, putting them onto a sound foundation, buying land for a new campus.
Washington University spent its first half century in downtown St. Louis bounded by Washington Ave. Lucas Place, Locust Street. By the 1890s, owing to the dramatic expansion of the Manual School and a new benefactor in Robert Brookings, the University began to move west; the University board of directors began a process to find suitable ground and hired the landscape architecture firm Olmsted, Olmsted & Eliot of Boston. A committee of Robert S. Brookings, Henry Ware Eliot, William Huse found a site of 103 acres just beyond Forest Park, located west of the city limits in St. Louis County; the elevation of the land was thought to resemble the Acropolis and inspired the nickname of "Hilltop" campus, renamed the Danforth campus in 2006 to honor former chancellor William H. Danforth. In 1899, the university opened a national design contest for the new campus; the renowned Philadelphia firm Cope & Stewardson won unanimously with its plan for a row of Collegiate Gothic quadrangles inspired by Oxford and Cambridge Universities.
The cornerstone of the first building, Busch Hall, was laid on October 20, 1900. The construction of Brookings Hall and Cupples began shortly thereafter; the school delayed occupying these buildings until 1905 to accommodate the 1904 World's Fair and Olympics. The delay allowed the university to construct ten buildings instead of t
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 a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit, greater than 1 is a hyperbola; the term derives its name from the parameters of conic sections, as every Kepler orbit is a conic section. It is used for the isolated two-body problem, but extensions exist for objects following a Klemperer 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. The eccentricity may take the following values: circular orbit: e = 0 elliptic orbit: 0 < e < 1 parabolic trajectory: e = 1 hyperbolic trajectory: e > 1 The eccentricity e is given by e = 1 + 2 E L 2 m red α 2 where E is the total orbital energy, L is the angular momentum, mred is the reduced mass, α the coefficient of the inverse-square law central force such as gravity or electrostatics in classical physics: F = α r 2 or in the case of a gravitational force: e = 1 + 2 ε h 2 μ 2 where ε is the specific orbital energy, μ the standard gravitational parameter based on the total mass, h the specific relative angular momentum.
For values of e from 0 to 1 the orbit's shape is an elongated ellipse. 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 hence eccentricity equal to one. Keeping the energy constant and reducing the angular momentum, elliptic and hyperbolic orbits each tend to the corresponding type of radial trajectory while e tends to 1. For a repulsive force only the hyperbolic trajectory, including the radial version, is applicable. For elliptical orbits, a simple proof shows that arcsin yields the projection angle of a perfect circle to an ellipse of eccentricity e. For example, to view the eccentricity of the planet Mercury, one must calculate the inverse sine to find the projection angle of 11.86 degrees. Next, tilt any circular object by that angle and the apparent ellipse projected to your eye will be of that same eccentricity; the word "eccentricity" comes from Medieval Latin eccentricus, derived from Greek ἔκκεντρος ekkentros "out of the center", from ἐκ- ek-, "out of" + κέντρον kentron "center".
"Eccentric" first appeared in English in 1551, with the definition "a circle in which the earth, sun. Etc. deviates from its center". By five years in 1556, an adjectival form of the word had developed; the eccentricity of an orbit can be calculated from the orbital state vectors as the magnitude of the eccentricity vector: e = | e | where: e is the eccentricity vector. For elliptical orbits it can 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: ra is the radius at apoapsis. Rp is the radius at periapsis; the eccentricity of an elliptical orbit can be used to obtain the ratio of the periapsis to the apoapsis: r p r a = 1 − e 1 + e For Earth, orbital eccentricity ≈ 0.0167, apoapsis= aphelion and periapsis= perihelion relative to sun. For Earth's annual orbit path, ra/rp ratio = longest_radius / shortest_radius ≈ 1.034 relative to center point of path. The eccentricity of the Earth's orbit is about 0.0167.
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Chandra X-ray Observatory
The Chandra X-ray Observatory known as the Advanced X-ray Astrophysics Facility, is a Flagship-class space telescope 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, enabled by the high angular resolution of its mirrors. Since the Earth's atmosphere absorbs the vast majority of X-rays, they are not detectable from Earth-based telescopes. Chandra is an Earth satellite in a 64-hour orbit, its mission is ongoing as of 2019. Chandra is one of the Great Observatories, along with the Hubble Space Telescope, Compton Gamma Ray Observatory, the Spitzer Space Telescope; the telescope is named after the Nobel Prize-winning Indian-American astrophysicist Subrahmanyan Chandrasekhar. Its mission is similar to that of ESA's XMM-Newton spacecraft launched in 1999. In 1976 the Chandra X-ray Observatory was proposed to NASA by Riccardo Giacconi and Harvey Tananbaum. Preliminary work began the following year at Marshall Space Flight Center and the Smithsonian Astrophysical Observatory.
In the meantime, in 1978, NASA launched the first imaging X-ray telescope, into orbit. Work continued on the AXAF project throughout the 1990s. In 1992, to reduce costs, the spacecraft was redesigned. Four of the twelve planned mirrors were eliminated. AXAF's planned orbit was changed to an elliptical one, reaching one third of the way to the Moon's at its farthest point; this eliminated the possibility of improvement or repair by the space shuttle but put the observatory above the Earth's radiation belts for most of its orbit. AXAF was tested by TRW in Redondo Beach, California. AXAF was renamed Chandra as part of a contest held by NASA in 1998, which drew more than 6,000 submissions worldwide; 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 maximum mass of white dwarf stars, leading to greater understanding of high energy astronomical phenomena such as neutron stars and black holes.
Fittingly, the name Chandra means "moon" in Sanskrit. Scheduled to be launched in December 1998, the spacecraft was delayed several months being launched in July 23, 1999, at 04:31 UTC by Space Shuttle Columbia during STS-93. Chandra was deployed from Columbia at 11:47 UTC; the Inertial Upper Stage's first stage motor ignited at 12:48 UTC, after burning for 125 seconds and separating, the second stage ignited at 12:51 UTC and burned for 117 seconds. At 22,753 kilograms, it was the heaviest payload launched by the shuttle, a consequence of the two-stage Inertial Upper Stage booster rocket system needed to transport the spacecraft to its high orbit. Chandra has been returning data since the month, it is operated by the SAO at the Chandra X-ray Center in Cambridge, with assistance from MIT and Northrop Grumman Space Technology. The ACIS CCDs suffered particle damage during early radiation belt passages. To prevent further damage, the instrument is now removed from the telescope's focal plane during passages.
Although Chandra was given an expected lifetime of 5 years, on September 4, 2001, NASA extended its lifetime to 10 years "based on the observatory's outstanding results." Physically Chandra could last much longer. A 2004 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 cancelled. ESA resurrected the project as the Advanced Telescope for High Energy Astrophysics with a proposed launch in 2028. On October 10, 2018, Chandra entered safe mode operations, due to a gyroscope glitch. NASA reported. Within days, the 3-second error in data from one gyro was understood, plans were made to return Chandra to full service; the gyroscope that experienced the glitch is otherwise healthy. The data gathered by Chandra has advanced the field of X-ray astronomy. Here are some examples of discoveries supported by observations from Chandra: The first light image, of supernova remnant Cassiopeia A, gave astronomers their first glimpse of the compact object at the center of the remnant a neutron star or black hole.
In the Crab Nebula, another supernova remnant, Chandra showed a never-before-seen ring around the central pulsar and jets that had only been seen by earlier telescopes. The first X-ray emission was seen from the supermassive black hole, Sagittarius A*, at the center of the Milky Way. Chandra found much more cool gas than expected spiraling into the center of the Andromeda Galaxy. Pressure fronts were observed in detail for the first time in Abell 2142, where clusters of galaxies are merging; the earliest images in X-rays of the shock wave of a supernova were taken of SN 1987A. Chandra showed for the first time the shadow of a small galaxy as it is being cannibalized by a larger one, in an image of Perseus A. A new type of black hole was discovered in galaxy M82, mid-mass objects purported to be the missing link between stellar-sized black holes and super massive black holes. X-ray emission lines were associated for the first time with a gamma-ray burst
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, modified for the Space Shuttle program. Launch Complex 39 is composed of three launch pads—39A, 39B and 39C, a Vehicle Assembly Building, a Crawlerway used by crawler-transporters to carry Mobile Launcher Platforms between the VAB and the pads, Orbiter Processing Facility buildings, a Launch Control Center which contains the firing rooms, a news facility famous for the iconic countdown clock seen in television coverage and photos, various logistical and operational support buildings; as of 2017, only Launch Pad 39A is active, has been used to launch SpaceX's Falcon 9 and Falcon Heavy. Pad 39B is being modified to launch NASA's Space Launch System. A new, smaller pad, 39C has not yet been used. 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, is preparing it for the Space Launch System with first launch scheduled for December 2019. Pad C was planned for Apollo but never built, 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 several launch sites that share radar and tracking services of the Eastern Test Range. Northern Merritt Island was first developed around 1890 when a few wealthy Harvard University graduates purchased 18,000 acres and constructed a three-story mahogany clubhouse nearly on the site of Pad 39A. During the 1920s, Peter E. Studebaker Jr. son of the automobile magnate, built a small casino at De Soto Beach eight miles north of the Canaveral lighthouse. 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 site's location on the East Florida coast was ideal for this purpose in that launches would be over the ocean, away from populated areas. 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, the future Cape Canaveral Air Force Station. 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 NASA's civilian unmanned and manned launches, including those of Project Mercury and Project Gemini. In 1961, President Kennedy proposed to Congress the goal of landing a man on the Moon by the end of the decade. Congressional approval led to the launch of the Apollo program, which required a massive expansion of NASA operations, including an expansion of launch operations from the Cape to adjacent Merritt Island to the north and west. NASA began acquisition of land in 1962, taking title to 131 square miles by outright purchase and negotiating with the state of Florida for an additional 87 square miles.
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; when the lunar launch complex was designed, it was designated as Launch Complex 39. It was designed to handle launches of the Saturn V rocket, the largest, most powerful rocket designed, which would propel Apollo spacecraft to the Moon. Initial plans included four pads evenly spaced 8,700 feet apart to avoid damage in the event of an explosion on the pad. Three were scheduled for construction and two would have been built at a date; the numbering of the pads at the time was from north to south, with the northernmost being 39A, the southernmost being 39C. Pad 39A was never built, 39C became 39A in 1963. With today's numbering, 39C would have been north of 39B, 39D would have been due west of 39C. Pad 39E would have been due north of the mid-distance between 39C and 39D, with 39E forming the top of a triangle, equidistant from 39C and 39D; the Crawlerway was built with the additional pads in mind.
This is the reason the Crawlerway turns as it heads to Pad B. Months before launch, the three stages of the Saturn V launch vehicle and the components of the Apollo spacecraft were brought inside the Vehicle Assembly Building and assembled in one of four high bays into a 363-foot -tall space vehicle on one of three Mobile Launchers; each mobile launcher consisted of a two-story, 161-by-135-foot launch platform with four hold-down arms and a 446-foot Launch Umbilical Tower topped by a crane used to lift the spacecraft into position for assembly. The MLP and unfueled vehicle together weighed 12,600,000 pounds; the Umbilical Tower contained two elevators and nine retractable swing arms which extended to the space vehicle, to provide access to each of the three rocket stages and the spacecraft for people and plumbing while the vehicle was on the launch pad, swung away from the vehicle at launch. Technicians and astronauts used the uppermost Spacecraft Access Arm to access the crew cabin. At the end of the arm, the white room provided an environmentally controlled and protected area for astronauts and their equipment to enter the spacecraft
