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Mass Concentration (astronomy)
In astronomy, astrophysics and geophysics, a mass concentration (or mascon) is a region of a planet's or moon's crust that contains a large positive gravity anomaly. In general, the word "mascon" can be used as a noun to refer to an excess distribution of mass on or beneath the surface of an astronomical body (compared to some suitable average), such as is found around Hawaii on Earth. However, this term is most often used to describe a geologic structure that has a positive gravitational anomaly associated with a feature (e.g. depressed basin) that might otherwise have been expected to have a negative anomaly, such as the "mascon basins" on the Moon. Lunar and Martian mascons The Moon is the most gravitationally "lumpy" major body known in the Solar System. Its largest mascons can cause a plumb bob to hang about a third of a degree off vertical, pointing toward the mascon, and increase the force of gravity by one-half percent. Typical examples of mascon basins on the Moon are t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithosphere
A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust (geology), crust and the portion of the upper mantle (geology), mantle that behaves elastically on time scales of up to thousands of years or more. The crust and upper mantle (Earth), upper mantle are distinguished on the basis of chemistry and mineralogy. Earth's lithosphere Earth's lithosphere, which constitutes the hard and rigid outer vertical layer of the Earth, includes the crust and the uppermost mantle. The lithosphere is underlain by the asthenosphere which is the weaker, hotter, and deeper part of the upper mantle. The lithosphere–asthenosphere boundary is defined by a difference in response to stress. The lithosphere remains rigid for very long periods of geologic time in which it deforms elastically and through brittle failure, while the asthenosphere deforms viscously and accommodates strain through plasticity (physics), pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jet Propulsion Laboratory
The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States. Founded in the 1930s by Caltech researchers, JPL is owned by NASA and managed by the nearby California Institute of Technology (Caltech). The laboratory's primary function is the construction and operation of planetary robotic spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating the NASA Deep Space Network. Among the laboratory's major active projects are the Mars 2020 mission, which includes the ''Perseverance'' rover and the '' Ingenuity'' Mars helicopter; the Mars Science Laboratory mission, including the ''Curiosity'' rover; the InSight lander (''Interior Exploration using Seismic Investigations, Geodesy and Heat Transport''); the ''Mars Reconnaissance Orbiter''; the ''Juno'' spacecraft orbiting Jupiter; the ''SMAP'' satellite for earth surface s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paul M
Paul may refer to: *Paul (given name), a given name (includes a list of people with that name) *Paul (surname), a list of people People Christianity * Paul the Apostle (AD c.5–c.64/65), also known as Saul of Tarsus or Saint Paul, early Christian missionary and writer *Pope Paul (other), multiple Popes of the Roman Catholic Church *Saint Paul (other), multiple other people and locations named "Saint Paul" Roman and Byzantine empire *Lucius Aemilius Paullus Macedonicus (c. 229 BC – 160 BC), Roman general *Julius Paulus Prudentissimus (), Roman jurist *Paulus Catena (died 362), Roman notary *Paulus Alexandrinus (4th century), Hellenistic astrologer *Paul of Aegina or Paulus Aegineta (625–690), Greek surgeon Royals * Paul I of Russia (1754–1801), Tsar of Russia *Paul of Greece (1901–1964), King of Greece Other people *Paul the Deacon or Paulus Diaconus (c. 720 – c. 799), Italian Benedictine monk *Paul (father of Maurice), the father of Maurice, Byz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luna 10
Luna 10 (or Lunik 10) was a 1966 Soviet lunar robotic spacecraft mission in the Luna program. It was the first artificial satellite of the Moon. Luna 10 conducted extensive research in lunar orbit, gathering important data on the strength of the Moon's magnetic field, its radiation belts, and the nature of lunar rocks (which were found to be comparable to terrestrial basalt rocks), cosmic radiation, and micrometeoroid density. Perhaps its most important finding was the first evidence of mass concentrations (called "mascons") — areas of high density below the mare basins that distort lunar orbital trajectories. Their discovery has usually been credited to the American Lunar Orbiter series. The spacecraft Part of the ''E-6S'' series, Luna 10 was battery powered and had an on-orbit dry mass of 540 kg. Scientific instruments included a gamma-ray spectrometer for energies between 0.3–3 MeV (50–500 pJ), a triaxial magnetometer, a meteorite detector, instrum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apollo 16
Apollo 16 (April 1627, 1972) was the tenth crewed mission in the United States Apollo space program, administered by NASA, and the fifth and penultimate to land on the Moon. It was the second of Apollo's " J missions", with an extended stay on the lunar surface, a focus on science, and the use of the Lunar Roving Vehicle (LRV). The landing and exploration were in the Descartes Highlands, a site chosen because some scientists expected it to be an area formed by volcanic action, though this proved to not be the case. The mission was crewed by Commander John Young, Lunar Module Pilot Charles Duke and Command Module Pilot Ken Mattingly. Launched from the Kennedy Space Center in Florida on April 16, 1972, Apollo 16 experienced a number of minor glitches en route to the Moon. These culminated with a problem with the spaceship's main engine that resulted in a six-hour delay in the Moon landing as NASA managers contemplated having the astronauts abort the mission and return to E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PFS-2
Apollo 16 (April 1627, 1972) was the tenth crewed mission in the United States Apollo space program, administered by NASA, and the fifth and penultimate to land on the Moon. It was the second of Apollo's " J missions", with an extended stay on the lunar surface, a focus on science, and the use of the Lunar Roving Vehicle (LRV). The landing and exploration were in the Descartes Highlands, a site chosen because some scientists expected it to be an area formed by volcanic action, though this proved to not be the case. The mission was crewed by Commander John Young, Lunar Module Pilot Charles Duke and Command Module Pilot Ken Mattingly. Launched from the Kennedy Space Center in Florida on April 16, 1972, Apollo 16 experienced a number of minor glitches en route to the Moon. These culminated with a problem with the spaceship's main engine that resulted in a six-hour delay in the Moon landing as NASA managers contemplated having the astronauts abort the mission and return to Ear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frozen Orbit
In orbital mechanics, a frozen orbit is an orbit for an artificial satellite in which natural drifting due to the central body's shape has been minimized by careful selection of the orbital parameters. Typically, this is an orbit in which, over a long period of time, the satellite's altitude remains constant at the same point in each orbit. Changes in the inclination, position of the apsis of the orbit, and eccentricity have been minimized by choosing initial values so that their perturbations cancel out., which results in a long-term stable orbit that minimizes the use of station-keeping propellant. Background and motivation For most spacecraft, changes to orbits are caused by the oblateness of the Earth, gravitational attraction from the sun and moon, solar radiation pressure, and air drag. These are called "perturbing forces". They must be counteracted by maneuvers to keep the spacecraft in the desired orbit. For a geostationary spacecraft, correction maneuvers on the order ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbit
In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a planet, moon, asteroid, or Lagrange point. Normally, orbit refers to a regularly repeating trajectory, although it may also refer to a non-repeating trajectory. To a close approximation, planets and satellites follow elliptic orbits, with the center of mass being orbited at a focal point of the ellipse, as described by Kepler's laws of planetary motion. For most situations, orbital motion is adequately approximated by Newtonian mechanics, which explains gravity as a force obeying an inverse-square law. However, Albert Einstein's general theory of relativity, which accounts for gravity as due to curvature of spacetime, with orbits following geodesics, provides a more accurate calculation and understanding of the exact mechanics of orbi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Heavy Bombardment
The Late Heavy Bombardment (LHB), or lunar cataclysm, is a hypothesized event thought to have occurred approximately 4.1 to 3.8 billion years (Ga) ago, at a time corresponding to the Neohadean and Eoarchean eras on Earth. According to the hypothesis, during this interval, a disproportionately large number of asteroids and comets collided with the early terrestrial planets in the inner Solar System, including Mercury, Venus, Earth and Mars. These came from both post-accretion and planetary instability-driven populations of impactors. Although widely accepted, it remains difficult to prove conclusively. Evidence for the LHB derives from rock samples of Moon craters brought back by the Apollo astronauts. Isotopic dating showed that the rocks were last molten during impact events in a rather narrow interval of time, suggesting that a large proportion of craters were formed during this period. Several hypotheses attempt to explain this apparent spike in the flux of impactors in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteroids
An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. Of the roughly one million known asteroids the greatest number are located between the orbits of Mars and Jupiter, approximately 2 to 4 AU from the Sun, in the main asteroid belt. Asteroids are generally classified to be of three types: C-type, M-type, and S-type. These were named after and are generally identified with carbonaceous, metallic, and silicaceous compositions, respectively. The size of asteroids varies greatly; the largest, Ceres, is almost across and qualifies as a dwarf planet. The total mass of all the asteroids combined is only 3% that of Earth's Moon. The majority of main belt asteroids follow slightly elliptical, stable orbits, revolving in the same direction as the Earth and taking from three to six years to comple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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