1.
Near-Earth object
–
A near-Earth object is any small Solar System body whose orbit brings it into proximity with Earth. By definition, a solar system body is a NEO if its closest approach to the Sun is less than 1.3 astronomical unit and it is now widely accepted that collisions in the past have had a significant role in shaping the geological and biological history of the Earth. NEOs have become of increased interest since the 1980s because of increased awareness of the potential danger some of the asteroids or comets pose, and mitigations are being researched. In January 2016, NASA announced the Planetary Defense Coordination Office to track NEOs larger than 30 to 50 meters in diameter and coordinate an effective threat response, NEAs have orbits that lie partly between 0.983 and 1.3 AU away from the Sun. When a NEA is detected it is submitted to the IAUs Minor Planet Center for cataloging, some NEAs orbits intersect that of Earths so they pose a collision danger. The United States, European Union, and other nations are currently scanning for NEOs in an effort called Spaceguard. In the United States and since 1998, NASA has a mandate to catalogue all NEOs that are at least 1 kilometer wide. In 2006, it was estimated that 20% of the objects had not yet been found. In 2011, largely as a result of NEOWISE, it was estimated that 93% of the NEAs larger than 1 km had been found, as of 5 February 2017, there have been 875 NEAs larger than 1 km discovered, of which 157 are potentially hazardous. The inventory is much less complete for smaller objects, which still have potential for scale, though not global. Potentially hazardous objects are defined based on parameters that measure the objects potential to make threatening close approaches to the Earth. Mostly objects with an Earth minimum orbit intersection distance of 0.05 AU or less, objects that cannot approach closer to the Earth than 0.05 AU, or are smaller than about 150 m in diameter, are not considered PHOs. This makes them a target for exploration. As of 2016, three near-Earth objects have been visited by spacecraft, more recently, a typical frame of reference for looking at NEOs has been through the scientific concept of risk. In this frame, the risk that any near-Earth object poses is typically seen through a lens that is a function of both the culture and the technology of human society, NEOs have been understood differently throughout history. Each time an NEO is observed, a different risk was posed and it is not just a matter of scientific knowledge. Such perception of risk is thus a product of religious belief, philosophic principles, scientific understanding, technological capabilities, and even economical resourcefulness.03 E −0.4 megatonnes. For instance, it gives the rate for bolides of 10 megatonnes or more as 1 per thousand years, however, the authors give a rather large uncertainty, due in part to uncertainties in determining the energies of the atmospheric impacts that they used in their determination
2.
433 Eros
–
433 Eros is an S-type near-Earth asteroid approximately 34. 4×11. 2×11.2 kilometres in size, the second-largest near-Earth asteroid after 1036 Ganymed. It was discovered in 1898 and was the first near-Earth asteroid discovered and it was the first asteroid orbited by an Earth probe. It belongs to the Amor group, Eros is a Mars-crosser asteroid, the first known to come within the orbit of Mars. Objects in such an orbit can remain there for only a few hundred years before the orbit is perturbed by gravitational interactions. It is a potential Earth impactor, about five times larger than the impactor that created Chicxulub crater, the NEAR Shoemaker probe visited Eros twice, first with a 1998 flyby, and then by orbiting it in 2000 when it extensively photographed its surface. On February 12,2001, at the end of its mission, Eros was discovered on 13 August 1898 by Gustav Witt in Berlin and Auguste Charlois at Nice. Witt was taking a 2-hour exposure of Beta Aquarii to secure astrometric positions of asteroid 185 Eunike, a similar program was then carried out, during a closer approach, in 1930–1931 by Harold Spencer Jones. The value obtained by this program was considered definitive until 1968, Eros was the first asteroid detected by the Arecibo Observatorys radar system. Eros was one of the first asteroids visited by a spacecraft, the first one orbited, NASA spacecraft NEAR Shoemaker entered orbit around Eros in 2000, and landed in 2001. Eros is named after the Greek god of love, Erōs and it is pronounced /ˈɪərɒs/ EER-os or sometimes /ˈɛrɒs/ ERR-os. The rarely used form of the name is Erotian /ᵻˈroʊʃən/. Surface gravity depends on the distance from a spot on the surface to the center of a bodys mass, eross surface gravity varies greatly because Eros is not a sphere but an elongated peanut-shaped object. The daytime temperature on Eros can reach about 100 °C at perihelion, nighttime measurements fall near −150 °C. Eross density is 2.67 g/cm3, about the same as the density of Earths crust and it rotates once every 5.27 hours. NEAR scientists have found that most of the larger rocks strewn across Eros were ejected from a crater in an impact approximately 1 billion years ago. This event may also be responsible for the 40 percent of the Erotian surface that is devoid of craters smaller than 0.5 kilometers across and it was originally thought that the debris thrown up by the collision filled in the smaller craters. An analysis of crater densities over the surface indicates that the areas with lower density are within 9 kilometers of the impact point. Some of the lower density areas were found on the side of the asteroid
3.
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
4.
Delta II
–
Delta II is an American expendable launch system, originally designed and built by McDonnell Douglas. Delta II is part of the Delta rocket family and entered service in 1989, Delta II vehicles included the Delta 6000, and two Delta 7000 variants. In the early 1980s, all United States expendable launch vehicles were planned to be phased out in favor of the Space Shuttle, production of Delta, Atlas-Centaur, and Titan 34D had ended. McDonnell Douglas, at time the manufacturer of the Delta family. These were intended to launch a series of GPS Block II satellites, the Air Force exercised additional contract options in 1988, expanding this order to 20 vehicles, and NASA purchased its first Delta IIs in 1990 for the launch of three Earth-observing satellites. The first Delta II launch occurred in 1989, with a Delta 6925 boosting the first GPS Block II satellite into a 20,000 km high orbit, the first Delta II 7000-series flew in 1990, replacing the RS-27 engine of the 6000-series with the more powerful RS-27A. Additionally, the steel-cased Castor 4A solid boosters of the 6000 series were replaced with the composite-cased GEM40, all further Delta II launches except three were of this upgraded configuration, and the 6000-series was retired in 1992. McDonnell Douglas began Delta III development in the mid-90s as increasing satellite mass required more powerful launch vehicles, the upgraded boosters would still find use on the Delta II, leading to the Delta II Heavy. In total, the Delta II family has launched 153 times, no one was injured, and the launch pad itself was not seriously impacted, though several cars were destroyed and a few buildings were damaged. In 2007, Delta II completed its 75th consecutive successful launch, with the launch of SMAP in 2015, the Delta II has enjoyed 98 consecutive successful launches, with two more scheduled in 2017 and 2018. Should these launches be successful, the Delta II would achieve an unprecedented 100 consecutive launch successes, the first stage of the Delta II is propelled by a Rocketdyne RS-27 main engine burning RP-1 and liquid oxygen. This stage is referred to as the Extra-Extended Long Tank Thor. The RS-27 used on the 6000-series Delta II produced 915 kN, the stage is 26 meters long and 2.4 meters wide, weighs over 100 t when fueled, and burns for 260 seconds. In addition, two LR101-NA-11 vernier engines provide guidance for the first stage, for additional thrust during launch, the Delta II uses solid boosters. For the 6000-series, Delta II used Castor 4A boosters, while the 7000-series uses Graphite-Epoxy Motors manufactured by ATK, the vehicle can be flown with three, four, or, most commonly, nine boosters. The second stage of Delta II is the Delta-K, powered by a restartable Aerojet AJ10-118K engine burning hypergolic Aerozine-50 and these propellants are highly toxic and corrosive, and once loaded the launch must occur within approximately 37 days or the stage will have to be refurbished or replaced. This stage also contains a combined platform and guidance system that controls all flight events. The Delta-K stage is 6 meters long and 2.4 meters wide, contains up to 6 t of propellant, for low Earth orbit, Delta II is not equipped with a third stage
5.
Cape Canaveral Air Force Station
–
Cape Canaveral Air Force Station is an installation of the United States Air Force Space Commands 45th Space Wing, headquartered at nearby Patrick Air Force Base. Located on Cape Canaveral in Brevard County, Florida, CCAFS is the primary head of Americas Eastern Range with three launch pads currently active. The Cape Canaveral Air Force Station Skid Strip provides a 10, 000-foot runway close to the launch complexes for military airlift aircraft delivering heavy, a number of American space exploration firsts were launched from CCAFS, including the first U. S. Earth satellite, first U. S. astronaut, first U. S. astronaut in orbit, first two-man U. S. spacecraft, first U. S. unmanned lunar landing, and first three-man U. S. spacecraft. The CCAFS area had used by the United States government to test missiles since 1949. On June 1,1948, the U. S. Navy transferred the former Banana River Naval Air Station to the U. S. Air Force, with USAF renaming the facility the Joint Long Range Proving Ground Base on June 10,1949. On October 1,1949, the Joint Long Range Proving Ground Base was transferred from the Air Materiel Command to the Air Force Division of the Joint Long Range Proving Ground. On May 17,1950, the base was renamed the Long Range Proving Ground Base, in 1951, the Air Force established the Air Force Missile Test Center. Early American sub-orbital rocket flights were achieved at Cape Canaveral in 1956 and these flights occurred shortly after sub-orbital flights launched from White Sands Missile Range, such as the Viking 12 sounding rocket on February 4,1955. Following the Soviet Unions successful Sputnik 1, the US attempted its first launch of a satellite from Cape Canaveral on December 6,1957. However, the rocket carrying Vanguard TV3 blew up on the launch pad, NASA was founded in 1958, and Air Force crews launched missiles for NASA from the Cape, known then as Cape Canaveral Missile Annex. The row of Titan and Atlas launch pads along the coast came to be known as Missile Row in the 1960s, nASAs first manned spaceflight program was prepared for launch from Canaveral by U. S. Air Force crews. Mercurys objectives were to place a spacecraft in Earth orbit, investigate human performance and ability to function in space. Suborbital flights were launched by derivatives of the Armys Redstone missile from LC-5, Orbital flights were launched by derivatives of the Air Forces larger Atlas D missile from LC-14. The first American in orbit was John Glenn on February 20,1962, three more orbital flights followed through May 1963. Flight control for all Mercury missions was provided at the Mercury Control Center located at Canaveral near LC-14 and he had also convinced Gov. C. Farris Bryant to change the name of Cape Canaveral to Cape Kennedy and this resulted in some confusion in public perception, which conflated the two. This name was used through the Gemini and early Apollo programs, however, the geographical name change proved to be unpopular, owing to the historical longevity of Cape Canaveral
6.
Discovery Program
–
NASAs Discovery Program is a series of lower-cost, highly focused American scientific space missions that are exploring the Solar System. It was founded in 1992 to implement then-NASA Administrator Daniel S. Goldins vision of faster, better, cheaper planetary missions, Discovery missions differ from traditional NASA missions where targets and objectives are pre-specified. Instead, these missions are proposed and led by a scientist called the Principal Investigator. Proposing teams may include people from industry, small businesses, government laboratories, proposals are selected through a competitive peer review process. All of the completed Discovery missions are accomplishing ground-breaking science and adding significantly to the body of knowledge about the Solar System, NASA also accepts proposals for competitively selected Discovery Program Missions of Opportunity. These opportunities are offered through NASAs Stand Alone Mission of Opportunity program. In 1989, the Solar System Exploration Division at NASA Headquarters initiated a series of workshops to define a new strategy for exploration through the year 2000, a fast-paced study for a potential mission was requested and funding arrangements were made in 1990. On February 17,1996, NEAR became the first mission to launch in the Discovery Program, also, Phoenix and MAVEN were in the Mars Scout Program not Discovery program. NEAR Shoemaker, a mission to study asteroid 433 Eros, launched on February 17,1996, the spacecraft entered orbit around Eros in 2000 and successfully touched down on its surface one year later. It has succeeded its primary and extended mission and is now complete, the Project Scientist was Andrew Chang of The Johns Hopkins University Applied Physics Laboratory. Mars Pathfinder, a Mars lander to deploy Sojourner rover on the surface, launched in 1996, it landed on Mars on July 4,1997. It has completed its primary and extended mission, the Principal Investigator was Matthew Golombek of NASA’s Jet Propulsion Laboratory. Lunar Prospector, a Moon orbiter to characterize the lunar mineralogy, launched in 1998, it spent 1½ years in lunar orbit. It has completed its primary and extended mission and deliberately impacted onto the Moons surface, the Principal Investigator was Alan Binder of the Lunar Research Institute. Stardust, a mission to collect interstellar dust and dust particles from the nucleus of comet 81P/Wild for study on Earth, launched in 1999, it successfully collected samples between 2000–2004, then the sample return capsule returned to Earth on January 15,2006. The capsule is on display at the National Air and Space Museum in Washington D. C, scientists worldwide are studying the comet dust samples while citizen scientists are finding interstellar dust bits through the Stardust@home project. The spacecraft was assigned a new task, called Stardust-NExT to revisit Tempel 1, having completed its primary and extend missions, Stardust did a final burn to deplete its remaining fuel on March 24,2011. The Principal Investigator was Donald Brownlee of the University of Washington, Genesis, a mission to collect solar wind charged particles for analysis on Earth
7.
Mars Pathfinder
–
Mars Pathfinder is an American robotic spacecraft that landed a base station with a roving probe on Mars in 1997. It consisted of a lander, renamed the Carl Sagan Memorial Station, and a lightweight wheeled robotic Mars rover named Sojourner, the lander then opened, exposing the rover which conducted many experiments on the Martian surface. The mission carried a series of instruments to analyze the Martian atmosphere, climate, geology. The mission was directed by the Jet Propulsion Laboratory, a division of the California Institute of Technology, the project manager was JPLs Tony Spear. This mission was the first of a series of missions to Mars that included rovers, although the Soviet Union successfully sent rovers to the Moon as part of the Lunokhod program in the 1970s, its attempts to use rovers in its Mars program failed. The Mars Pathfinder was also remarkable for its low cost relative to other unmanned space missions to Mars. Originally, the mission was conceived as the first of the Mars Environmental Survey program, to prove that the development of faster, better and cheaper spacecraft was possible. To show that it was possible to send a load of scientific instruments to another planet with a simple system, to demonstrate NASAs commitment to low-cost planetary exploration by finishing the mission with a total expenditure of $280 million, including the launch vehicle and mission operations. The Mars Pathfinder conducted different investigations on the Martian soil using three scientific instruments, the MET structure included three windsocks mounted at three heights on a pole, the topmost at about one meter and generally registered winds from the West. The Sojourner rover had an Alpha Proton X-ray Spectrometer, which was used to analyze the components of the rocks, the rover also had two black-and-white cameras and a color one. A third camera with the resolution but taking color images was located on the back, near the APXS. It provided images of the APXSs target area and the tracks on the ground. All three cameras were CCDs manufactured by Eastman Kodak Company, and were controlled by the rovers CPU and they all had auto-exposure and capabilities for handling bad pixels, and the image parameters were included in the transmitted images as part of the image header. The rover could compress the front cameras images using the block truncation coding algorithm, the cameras optical resolution was sufficient to resolve 0.6 cm details across a 0.65 m range. Scientists chose it because they found it to be a relatively safe surface to land on and one that contained a wide variety of rocks deposited during a catastrophic flood. After the landing, at 19. 13°N33. 22°W /19.13, -33.22, succeeded, the landers on-board computer used redundant on-board accelerometers to determine the timing of the parachute inflation. Twenty seconds later the heatshield was pyrotechnically released, another twenty seconds later the lander was separated and lowered from the backshell on a 20 m bridle. When the lander reached 1.6 km above the surface and this information was used by the computer to determine the precise timing of the landing events that followed
8.
Robotic spacecraft
–
A robotic spacecraft is an uncrewed spacecraft, usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to lower cost, in addition, some planetary destinations such as Venus or the vicinity of Jupiter are too hostile for human survival, given current technology. Outer planets such as Saturn, Uranus, and Neptune are too distant to reach with current crewed spaceflight technology, many artificial satellites are robotic spacecraft, as are many landers and rovers. The first robotic spacecraft was launched by the Soviet Union on 22 July 1951, four other such flights were made through the fall of 1951. The first artificial satellite, Sputnik 1, was put into a 215-by-939-kilometer Earth orbit by the USSR) on 4 October 1957, on 3 November 1957, the USSR orbited Sputnik 2. Weighing 113 kilograms, Sputnik 2 carried the first living animal into orbit, since the satellite was not designed to detach from its launch vehicles upper stage, the total mass in orbit was 508.3 kilograms. In a close race with the Soviets, the United States launched its first artificial satellite, Explorer 1, into a 193-by-1, 373-nautical-mile orbit on 31 January 1958. Explorer I was a 80. 75-inch long by 6. 00-inch diameter cyllynder weighing 30.8 pounds, compared to Sputnik 1, a 58-centimeter sphere which weighed 83.6 kilograms. Explorer 1 carried sensors which confirmed the existence of the Van Allen belts, on 17 March 1958, the US orbited its second satellite, Vanguard 1, which was about the size of a grapefruit, and remains in a 360-by-2, 080-nautical-mile orbit as of 2016. Nine other countries have successfully launched satellites using their own vehicles, France, Australia, Japan and China, the United Kingdom, India, Israel, Iran. In spacecraft design, the United States Air Force considers a vehicle to consist of the mission payload, the bus provides physical structure, thermal control, electrical power, attitude control and telemetry, tracking and commanding. JPL divides the system of a spacecraft into subsystems. These include, This is the backbone structure. It, provides overall mechanical integrity of the spacecraft ensures spacecraft components are supported and can withstand launch loads This is sometimes referred to as the command, components in the telecommunications subsystem include radio antennas, transmitters and receivers. These may be used to communicate with stations on Earth. The supply of power on spacecraft generally come from photovoltaic cells or from a radioisotope thermoelectric generator. Other components of the subsystem include batteries for storing power and distribution circuitry that connects components to the power sources, spacecraft are often protected from temperature fluctuations with insulation
9.
Space probe
–
A space probe is a robotic spacecraft that does not orbit the Earth, but, instead, explores further into outer space. A space probe may approach the Moon, travel through space, flyby, orbit, or land on other planetary bodies. Approximately fifteen missions are currently operational, once a probe has left the vicinity of Earth, its trajectory will likely take it along an orbit around the Sun similar to the Earths orbit. To reach another planet, the simplest practical method is a Hohmann transfer orbit, more complex techniques, such as gravitational slingshots, can be more fuel-efficient, though they may require the probe to spend more time in transit. Some high Delta-V missions can only be performed, within the limits of modern propulsion, a technique using very little propulsion, but requiring a considerable amount of time, is to follow a trajectory on the Interplanetary Transport Network. First man-made object to land on the Moon, or any other extra terrestrial surface. First mission to photograph the far side of the Moon, launched in 1959, first robotic sample return probe from the Moon. It was sent to the Moon on November 10,1970, first successful in-place analysis of another planet. It may have also been the first space probe to impact the surface of another planet, the Venera 7 probe was the first spacecraft to successfully soft land on another planet and to transmit data from there back to Earth. Upon its arrival at Mars on November 13,1971, Mariner 9 became the first space probe to orbit around another planet. Although, the spacecraft failed shortly after landing, the Mars Exploration Rovers, Spirit and Opportunity surface and geology, and searched for clues to past water activity on Mars. They were each launched in 2003 and landed in 2004, communication with Spirit stopped on sol 2210. JPL continued to attempt to regain contact until May 24,2011, Opportunity arrived at Endeavour crater on 9 August 2011, at a landmark called Spirit Point named after its rover twin, after traversing 13 miles from Victoria crater, over a three-year period. As of January 26,2016, Opportunity has lasted for more than twelve years on Mars — although the rovers were intended to last only three months. The first dedicated missions to a comet, in this case and they dropped landers and balloons at Venus before their rendezvous with Halleys Comet. This Japanese probe was the first non-US, non-Soviet interplanetary probe, a second Japanese probe, it made ultraviolet wavelength observations of the comet. The first space probe to penetrate a comets coma and take images of its nucleus. First solar wind sample return probe from sun-earth L1, first sample return probe from a comet tail
10.
Johns Hopkins University
–
The Johns Hopkins University is an American private research university in Baltimore, Maryland. Founded in 1876, the university was named for its first benefactor, the American entrepreneur, abolitionist and his $7 million bequest—of which half financed the establishment of The Johns Hopkins Hospital—was the largest philanthropic gift in the history of the United States at that time. Daniel Coit Gilman, who was inaugurated as the institutions first president on February 22,1876, led the university to revolutionize higher education in the U. S. by integrating teaching and research. Adopting the concept of a school from Germanys ancient Heidelberg University. Johns Hopkins is organized into 10 divisions on campuses in Maryland and Washington, D. C. with international centers in Italy, China, and Singapore. The two undergraduate divisions, the Krieger School of Arts and Sciences and the Whiting School of Engineering, are located on the Homewood campus in Baltimores Charles Village neighborhood. The medical school, the school, and the Bloomberg School of Public Health are located on the Medical Institutions campus in East Baltimore. Johns Hopkins was a member of the American Association of Universities. Over the course of almost 140 years, thirty-six Nobel laureates have been affiliated with Johns Hopkins, founded in 1883, the Blue Jays men’s lacrosse team has captured 44 national titles and joined the Big Ten Conference as an affiliate member in 2014. On his death in 1873, Johns Hopkins, a Quaker entrepreneur and childless bachelor, bequeathed $7 million to fund a hospital and university in Baltimore, Maryland. At that time this fortune, generated primarily from the Baltimore, the first name of philanthropist Johns Hopkins is the surname of his great-grandmother, Margaret Johns, who married Gerard Hopkins. They named their son Johns Hopkins, who named his own son Samuel Hopkins, Samuel named one of his sons for his father and that son would become the universitys benefactor. Milton Eisenhower, a university president, once spoke at a convention in Pittsburgh where the Master of Ceremonies introduced him as President of John Hopkins. Eisenhower retorted that he was glad to be here in Pittburgh, the original board opted for an entirely novel university model dedicated to the discovery of knowledge at an advanced level, extending that of contemporary Germany. Building on the German education model of Wilhelm von Humboldt, it dedicated to research. Johns Hopkins thereby became the model of the research university in the United States. Its success eventually shifted higher education in the United States from a focus on teaching revealed and/or applied knowledge to the discovery of new knowledge. The trustees worked alongside four notable university presidents – Charles W. Eliot of Harvard, Andrew D. White of Cornell, Noah Porter of Yale College and they each vouched for Daniel Coit Gilman to lead the new University and he became the universitys first president
11.
Mineral
–
A mineral is a naturally occurring chemical compound, usually of crystalline form and abiogenic in origin. A mineral has one specific chemical composition, whereas a rock can be an aggregate of different minerals or mineraloids, the study of minerals is called mineralogy. There are over 5,300 known mineral species, over 5,070 of these have been approved by the International Mineralogical Association, the silicate minerals compose over 90% of the Earths crust. The diversity and abundance of species is controlled by the Earths chemistry. Silicon and oxygen constitute approximately 75% of the Earths crust, which translates directly into the predominance of silicate minerals, minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various species, changes in the temperature, pressure, or bulk composition of a rock mass cause changes in its minerals. Minerals can be described by their various properties, which are related to their chemical structure. Common distinguishing characteristics include crystal structure and habit, hardness, lustre, diaphaneity, colour, streak, tenacity, cleavage, fracture, parting, more specific tests for describing minerals include magnetism, taste or smell, radioactivity and reaction to acid. Minerals are classified by key chemical constituents, the two dominant systems are the Dana classification and the Strunz classification, the silicate class of minerals is subdivided into six subclasses by the degree of polymerization in the chemical structure. All silicate minerals have a unit of a 4− silica tetrahedron—that is, a silicon cation coordinated by four oxygen anions. These tetrahedra can be polymerized to give the subclasses, orthosilicates, disilicates, cyclosilicates, inosilicates, phyllosilicates, other important mineral groups include the native elements, sulfides, oxides, halides, carbonates, sulfates, and phosphates. The first criterion means that a mineral has to form by a natural process, stability at room temperature, in the simplest sense, is synonymous to the mineral being solid. More specifically, a compound has to be stable or metastable at 25 °C, modern advances have included extensive study of liquid crystals, which also extensively involve mineralogy. Minerals are chemical compounds, and as such they can be described by fixed or a variable formula, many mineral groups and species are composed of a solid solution, pure substances are not usually found because of contamination or chemical substitution. Finally, the requirement of an ordered atomic arrangement is usually synonymous with crystallinity, however, crystals are also periodic, an ordered atomic arrangement gives rise to a variety of macroscopic physical properties, such as crystal form, hardness, and cleavage. There have been recent proposals to amend the definition to consider biogenic or amorphous substances as minerals. The formal definition of an approved by the IMA in 1995, A mineral is an element or chemical compound that is normally crystalline. However, if geological processes were involved in the genesis of the compound, Mineral classification schemes and their definitions are evolving to match recent advances in mineral science
12.
Mass
–
In physics, mass is a property of a physical body. It is the measure of a resistance to acceleration when a net force is applied. It also determines the strength of its gravitational attraction to other bodies. The basic SI unit of mass is the kilogram, Mass is not the same as weight, even though mass is often determined by measuring the objects weight using a spring scale, rather than comparing it directly with known masses. An object on the Moon would weigh less than it does on Earth because of the lower gravity and this is because weight is a force, while mass is the property that determines the strength of this force. In Newtonian physics, mass can be generalized as the amount of matter in an object, however, at very high speeds, special relativity postulates that energy is an additional source of mass. Thus, any body having mass has an equivalent amount of energy. In addition, matter is a defined term in science. There are several distinct phenomena which can be used to measure mass, active gravitational mass measures the gravitational force exerted by an object. Passive gravitational mass measures the force exerted on an object in a known gravitational field. The mass of an object determines its acceleration in the presence of an applied force, according to Newtons second law of motion, if a body of fixed mass m is subjected to a single force F, its acceleration a is given by F/m. A bodys mass also determines the degree to which it generates or is affected by a gravitational field and this is sometimes referred to as gravitational mass. The standard International System of Units unit of mass is the kilogram, the kilogram is 1000 grams, first defined in 1795 as one cubic decimeter of water at the melting point of ice. Then in 1889, the kilogram was redefined as the mass of the prototype kilogram. As of January 2013, there are proposals for redefining the kilogram yet again. In this context, the mass has units of eV/c2, the electronvolt and its multiples, such as the MeV, are commonly used in particle physics. The atomic mass unit is 1/12 of the mass of a carbon-12 atom, the atomic mass unit is convenient for expressing the masses of atoms and molecules. Outside the SI system, other units of mass include, the slug is an Imperial unit of mass, the pound is a unit of both mass and force, used mainly in the United States
.jpg)
_mathilde_crop.jpg)
