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Mini-RF
The Miniature Radio-Frequency instrument (Mini-RF) is a synthetic aperture radar (SAR) instrument on the Lunar Reconnaissance Orbiter (LRO), which is currently in orbit around the Moon. It has a resolution of 30 m/pixel and two wavelength bands, a primary band at 12.6 cm and a secondary band at 4.2 cm. The original principal investigator of Mini-RF, Stewart Nozette, was arrested for espionage. Nozette was replaced by Ben Bussey, then of APL, the Applied Physics Laboratory where Mini-RF was assembled from components developed by a consortium of industry team members. Bussey accepted a position at NASA Headquarters and was replaced by the current principal investigator, Wes Patterson, also of APL. Previous SAR instruments, such as the radar on the Magellan mission to Venus, were large, massive, power-hungry, and expensive. Intended as a demonstration of cheap, lightweight SAR technology, the Mini-RF instrument was designed in response to these concerns. Because it was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Water
Lunar water is water that is present on the Moon. Diffuse water molecules can persist at the Moon's sunlit surface, as discovered by NASA's SOFIA observatory in 2020. Gradually water vapor is decomposed by sunlight, leaving hydrogen and oxygen lost to outer space. Scientists have found water ice in the cold, permanently shadowed craters at the Moon's poles. Water molecules are also present in the extremely thin lunar atmosphere. Water (H2O), and the chemically related hydroxyl group (-OH), exist in forms chemically bound as hydrates and hydroxides to lunar minerals (rather than free water), and evidence strongly suggests that this is the case in low concentrations as for much of the Moon's surface. In fact, of surface matter, adsorbed water is calculated to exist at trace concentrations of 10 to 1000 parts per million. Inconclusive evidence of free water ice at the lunar poles had accumulated during the second half of the 20th century from a variety of observations suggestin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Reconnaissance Orbiter
The Lunar Reconnaissance Orbiter (LRO) is a NASA robotic spacecraft currently orbiting the Moon in an eccentric polar mapping orbit. Data collected by LRO have been described as essential for planning NASA's future human and robotic missions to the Moon. Its detailed mapping program is identifying safe landing sites, locating potential resources on the Moon, characterizing the radiation environment, and demonstrating new technologies. Launched on June 18, 2009, in conjunction with the Lunar Crater Observation and Sensing Satellite (LCROSS), as the vanguard of NASA's Lunar Precursor Robotic Program, LRO was the first United States mission to the Moon in over ten years. LRO and LCROSS were launched as part of the United States's Vision for Space Exploration program. The probe has made a 3-D map of the Moon's surface at 100-meter resolution and 98.2% coverage (excluding polar areas in deep shadow), including 0.5-meter resolution images of Apollo landing sites. The first images f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stewart Nozette
Stewart David Nozette (born May 20, 1957) is an American planetary scientist, technologist, and consultant who worked for the United States Department of Energy, the United States Department of Defense, DARPA, the United States Naval Research Laboratory, and NASA.Agence France-Presse (2009). He is also a convicted felon for attempted espionage and fraud against the United States. The FBI arrested him October 19, 2009,New York TimesThe Scientist Who Mistook Himself for a Spy Oct 21 2009; also ''New York Times'', October 20, 2009, page A19 charging him with attempted espionage after a sting operationMartell (2009). which Nozette's lawyer claims amounted to entrapment.Washington PostMaryland scientist Stewart Nozette sentenced for passing secrets to supposed Mossad agent, expresses regret Mar 12 2012 At trial, Nozette admitted attempting to sell Classified information in the United States, U.S. classified information to someone he believed was an Israeli Mossad operative, but was in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LCROSS
The Lunar Crater Observation and Sensing Satellite (LCROSS) was a robotic spacecraft operated by NASA. The mission was conceived as a low-cost means of determining the nature of hydrogen detected at the polar regions of the Moon. Launched immediately after discovery of lunar water by Chandrayaan-1, the main LCROSS mission objective was to further explore the presence of water in the form of ice in a permanently shadowed crater near a lunar polar region. It was successful in confirming water in the southern lunar crater Cabeus. It was launched together with the Lunar Reconnaissance Orbiter (LRO) on June 18, 2009, as part of the shared Lunar Precursor Robotic Program, the first American mission to the Moon in over ten years. LCROSS was designed to collect and relay data from the impact and debris plume resulting from the launch vehicle's spent Centaur upper stage (and data-collecting Shepherding Spacecraft) striking the crater Cabeus near the south pole of the Moon. Centaur had ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synthetic Aperture Radar
Synthetic-aperture radar (SAR) is a form of radar that is used to create two-dimensional images or three-dimensional reconstructions of objects, such as landscapes. SAR uses the motion of the radar antenna over a target region to provide finer spatial resolution than conventional stationary beam-scanning radars. SAR is typically mounted on a moving platform, such as an aircraft or spacecraft, and has its origins in an advanced form of side looking airborne radar (SLAR). The distance the SAR device travels over a target during the period when the target scene is illuminated creates the large ''synthetic'' antenna aperture (the ''size'' of the antenna). Typically, the larger the aperture, the higher the image resolution will be, regardless of whether the aperture is physical (a large antenna) or synthetic (a moving antenna) – this allows SAR to create high-resolution images with comparatively small physical antennas. For a fixed antenna size and orientation, objects which are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of Australia). The Moon is a planetary-mass object with a differentiated rocky body, making it a satellite planet under the geophysical definitions of the term and larger than all known dwarf planets of the Solar System. It lacks any significant atmosphere, hydrosphere, or magnetic field. Its surface gravity is about one-sixth of Earth's at , with Jupiter's moon Io being the only satellite in the Solar System known to have a higher surface gravity and density. The Moon orbits Earth at an average distance of , or about 30 times Earth's diameter. Its gravitational influence is the main driver of Earth's tides and very slowly lengthens Earth's day. The Moon's orbit around Earth has a sidereal period of 27.3 days. During each synodic period ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Applied Physics Laboratory
The Johns Hopkins University Applied Physics Laboratory (Applied Physics Laboratory, or APL) is a not-for-profit University Affiliated Research Center, university-affiliated research center (UARC) in Howard County, Maryland. It is affiliated with Johns Hopkins University and employs 8,000 people (2022). The lab serves as a technical resource for the United States Department of Defense, Department of Defense, NASA, and other government agencies. APL has developed numerous systems and technologies in the areas of air and missile defense, surface and undersea naval warfare, computer security, and space science and spacecraft construction. While APL provides research and engineering services to the government, it is not a traditional defense contractor, as it is a UARC and a division of Johns Hopkins University. APL is a scientific and engineering research and development division, rather than an academic division, of Johns Hopkins. Hopkins' Whiting School of Engineering offers par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magellan (spacecraft)
The ''Magellan'' spacecraft was a robotic space probe launched by NASA of the United States, on May 4, 1989, to map the surface of Venus by using synthetic-aperture radar and to measure the planetary gravitational field. The ''Magellan'' probe was the first interplanetary mission to be launched from the Space Shuttle, the first one to use the Inertial Upper Stage booster, and the first spacecraft to test aerobraking as a method for circularizing its orbit. ''Magellan'' was the fifth successful NASA mission to Venus, and it ended an eleven-year gap in U.S. interplanetary probe launches. History Beginning in the late 1970s, scientists advocated for a radar mapping mission to Venus. They first sought to construct a spacecraft named the ''Venus Orbiting Imaging Radar'' (VOIR), but it became clear that the mission would be beyond the budget constraints during the ensuing years. The VOIR mission was canceled in 1982. A simplified radar mission proposal was recommended by the Solar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Venus
Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never far from the Sun, either as morning star or evening star. Aside from the Sun and Moon, Venus is the brightest natural object in Earth's sky, capable of casting visible shadows on Earth at dark conditions and being visible to the naked eye in broad daylight. Venus is the second largest terrestrial object of the Solar System. It has a surface gravity slightly lower than on Earth and has a very weak induced magnetosphere. The atmosphere of Venus, mainly consists of carbon dioxide, and is the densest and hottest of the four terrestrial planets at the surface. With an atmospheric pressure at the planet's surface of about 92 times the sea level pressure of Earth and a mean temperature of , the carbon dioxide gas at Venus's surface is in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adsorbed
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a fluid (the ''absorbate'') is dissolved by or permeates a liquid or solid (the ''absorbent''). Adsorption is a '' surface phenomenon'', while absorption involves the whole volume of the material, although adsorption does often precede absorption. The term ''sorption'' encompasses both processes, while ''desorption'' is the reverse of it. Like surface tension, adsorption is a consequence of surface energy. In a bulk material, all the bonding requirements (be they ionic, covalent or metallic) of the constituent atoms of the material are fulfilled by other atoms in the material. However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates. The exact nature of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bistatic Radar
Bistatic radar is a radar system comprising a transmitter and receiver that are separated by a distance comparable to the expected target distance. Conversely, a conventional radar in which the transmitter and receiver are co-located is called a monostatic radar. A system containing multiple spatially diverse monostatic or bistatic radar components with a shared area of coverage is called ''multistatic radar''. Many long-range air-to-air and surface-to-air missile systems use semi-active radar homing, which is a form of bistatic radar. Types Pseudo-monostatic radars Some radar systems may have separate transmit and receive antennas, but if the angle subtended between transmitter, target and receiver (the bistatic angle) is close to zero, then they would still be regarded as monostatic or pseudo-monostatic. For example, some very long range HF radar systems may have a transmitter and receiver which are separated by a few tens of kilometres for electrical isolation, but as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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