- Industry: Astronomy
- Number of terms: 6727
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Planetary Science Research Discoveries (PSRD) is an educational site sharing the latest research by NASA-sponsored scientists on meteorites, asteroids, planets, moons, and other materials in our Solar System. The website is supported by the Cosmochemistry Program of NASA's Science Mission ...
The geologic history of Mars has been divided into three broad time periods, or Epochs. From oldest to youngest, these are Noachian, Hesperian, and Amazonian (named after places on Mars). These Epochs are defined by the number of impact craters on the ground surface; older surfaces have more craters. The Hesperian Epoch extends from about 3. 5 to about 1. 8 billion years ago. The actual timing of the Epochs is not known because we have different models of the rates of meteorite falls on Mars.
Industry:Astronomy
A NASA Moon-orbiting mission launched in the fall of 2008. Its low-polar orbit and instrument payload is acquiring new data in support of future human landing sites and resource exploration including polar volatiles (especially water ice). These data include high-resolution imaging and topography, lunar radiation environment, and global surface composition. The Lunar Crater Observation and Sensing Satellite (LCROSS) launched with LRO, then traveled independently for a controlled crash on October 9, 2009 into a permanently-shadowed crater at the lunar south pole to support our search for water ice. An estimated 5. 6 ± 2. 9% by mass water ice was reported in the regolith at the LCROSS impact site, Cabeus crater.
Industry:Astronomy
Landing site of Apollo 12 on the Moon on Nov. 19, 1969; Oceanus Procellarum.
Industry:Astronomy
Iron meteorites are made, almost completely, of iron and nickel metal. They are chemically distinguished and grouped according to the abundances of the trace elements such as gallium and germanium, as well as nickel. Initially, irons were classified into four groups and were given Roman numerals I, II, III, and IV. Today twelve groups are recognized and designated further by letters A through F according to concentrations of siderophile ("iron-loving") trace elements. Iron meteorites that do not fit into the groups are called ungrouped. The two iron-nickel alloys in iron meteorites are called kamacite (low-nickel content, usually up to 7. 5 wt% nickel) and taenite (high-nickel content, ~20 to 50 wt% nickel). These alloys are rare in terrestrial rocks. (See also Widmanstätten Pattern. )
Industry:Astronomy
U. S. Discovery-class mission to the Moon launched on January 6, 1998. Its instruments were designed to provide global maps and data sets of the Moon's composition and magnetic and gravity fields from a low polar orbit. The mission lasted 18 months and ended July 31, 1999 with a controlled crash landing into a crater at the Moon's south pole.
Industry:Astronomy
The portion of Earth, or other planet, that is water, including liquid water, ice, and water vapor on the surface, underground, or in the atmosphere.
Industry:Astronomy
MgAl<sub>2</sub>O<sub>4</sub>, magnesium aluminum oxide mineral, with Cr able to substitute for Al.
Industry:Astronomy
A temperature scale that assigns the value 0° C to the freezing point of water and the value of 100° C to the boiling point of water at standard pressure. To convert Celsius to Fahrenheit: Multiply by 9, then divide by 5, then add 32.
Industry:Astronomy
