- 行业: 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 time interval that represents how long a surface of an airless body or a meter-sized or smaller asteroid traveled in space; based on measurements of accumulated radionuclides in the meteorite that were produced by exposure to the cosmic rays in space.
Industry:Astronomy
A compound formed by combining one carbon atom with two oxygen atoms, making the molecule CO<sub>2</sub>. Carbon dioxide is an important part of the atmospheres of Venus and Mars. Carbon dioxide gas condenses to a solid below -78° C. This solid is commonly known as dry ice. The polar ice caps on Mars are made of frozen water and carbon dioxide.
Industry:Astronomy
Naturally occurring inorganic solid with a definite chemical composition and crystal structure.
Industry:Astronomy
A meteorite that was not observed falling through the Earth's atmosphere, but was found at some later date.
Industry:Astronomy
Long, narrow wavelike folds in the surface of lava flows; formed where lava may have buckled up against slower moving or stationary lava downstream.
Industry:Astronomy
A local day on a planet, defined by its period of rotation. On Mars, for example, a local day lasts 24 hours and 37 minutes. During the Mars Pathfinder mission, scientists began counting Sols with the successful landing of the spacecraft on July 4, 1997 (Sol 1). Images from the Mars Pathfinder mission always contain a reference to the Sol on which it was taken.
Industry:Astronomy
Shallow depression, resembling a thumb print in clay, that is commonly seen on meteorites. Regmaglypts are formed by ablation from the surface by vortices of hot gas as a meteor falls through a planetary atmosphere.
Industry:Astronomy
Term referring to the idea that a sharp increase in impact bombardment rate between about 3. 92 and 3. 85 billion years ago affected the inner Solar System--most notably recorded in the numerous craters and large basins on the Moon.
Industry:Astronomy
A geochemical component in lunar rocks rich in potassium (K), rare-earth elements (REE), phosphorus (P), thorium, and other incompatible elements. These elements are not incorporated into common rock-forming minerals during magma crystallization, hence they become enriched in the residual magma and in the rocks finally formed from it.
Industry:Astronomy
