Lunar and Planetary Institute


Ancient Life on Mars


achondrite - A stony meteorite that lacks chondrules, which are small round granules of extraterrestrial origin found in most meteorites.
anorthite - A feldspar mineral, rich in calcium, that occurs in igneous rocks.

ANSMET - The Antarctic Search for Meteorites, a group of meteorite hunters sponsored annually by the U.S., with funding provided by the National Science Foundation and NASA. The first ANSMET team joined Japanese explorers to hunt for meteorites in Antarctica in 1976, and more than 7500 meteorite samples have been collected since then.

archaeon - A type of bacteria that has different chemicals from common bacteria.

basalt - A common type of fine-grained, volcanic rock, composed primarily of the minerals pyroxene and plagioclase.

chondrite - A meteorite that contains chondrules, which are small round granules of extraterrestrial origin found in most meteorites.

chromite - An opaque black mineral containing iron and chromium, FeCr2O4.

dendritic - In the shape of a tree, with many sets of smaller and smaller branches.

eucaryote - Also spelled eukaryote; a single-celled or multicellular organism whose cells contain a distinct membrane-bound nucleus.

fusion crust - A thin glassy coating, usually black and rarely exceeding one millimeter in thickness, formed on the surface of a meteorite by frictional heating during atmospheric flight.

greigite - A dark mineral with spinel-like structure, Fe3S4.

igneous - Term used to describe a rock or mineral that solidified from molten or partly molten material, i.e., from a magma; also used to describe processes leading to, related to, or resulting from the formation of such rocks.

iron meteorite - A general name for meteorites consisting primarily of an alloy of iron and nickel metal.

magnesite - A white to grayish, yellow, or brown mineral, MgCO3.

magnetite - A black, cubic, strongly magnetic, opaque mineral, Fe3O4.

meteorite - An extraterrestrial rock that has fallen to Earth. Most meteorites are pieces of asteroids; a few meteorites are known to come from the Moon or from Mars.

polycyclic aromatic hydrocarbons - Commonly referred to as PAHs, these compounds form easily by heating almost any organic or carbon-rich material; for example, PAHs form when red meat is burnt, and they have been found to be linked to cancer. Aromatic hydrocarbons contain flat rings of carbon atoms, usually six carbons arranged in a hexagon; polycyclic means that the molecules contain more than one "aromatic" ring.

pyrrhotite - A yellow-tan iron sulfide mineral, approximately FeS.

siderite - An orangish to black or brown mineral, FeCO3.

SNC meteorite - One of the 12 meteorites thought to have come from Mars. The letters SNC stand for the three types of meteorites: Shergottites, Nakhlites, and Chassigny.

stony meteorite - Meteorites consisting largely or entirely of silicate minerals (chiefly olivine, pyroxene, and plagioclase); e.g., chondrites and achondrites. Stony meteorites constitute more than 90% of all meteorites that have been found on Earth.

Back to introduction | Back to slide index

Back to top | Back to LPI Slide Sets | Back to LPI Home page