Mapping the Martian home of life evidence.A potato-sized meteorite meteorite, meteor that survives the intense heat of atmospheric friction and reaches the earth's surface. Because of the destructive effects of this friction, only the very largest meteors become meteorites. hit the headlines this month when NASA NASA: see National Aeronautics and Space Administration. NASA in full National Aeronautics and Space Administration Independent U.S. scientists reported persuasive signs of ancient life in this fragment of Mars (SN: 8/10/96, p. 84). Astronomers believe that asteroid impacts on Mars threw the meteorite and others into space, and Nadine G. Barlow of the University of Central Florida “UCF” redirects here. For other uses, see UCF (disambiguation). UCF is a member institution of the State University System of Florida. UCF was founded in 1963 as Florida Technological University with the goal of providing highly trained personnel to support the Kennedy in Orlando is pinpointing where the telltale rock originated. Using clues from the meteorite's composition and structure, the planetary scientist winnowed its place of origin down to 2 out of 42,283 Mars impact craters in her computer database. Barlow says the rock's 4.5-billion-year-old age indicates that it came from the impact-pitted highlands of the planet's southern hemisphere-the oldest terrain on Mars. Furthermore, microscopic signs of shock in the ancient rock reveal that the meterorite's home crater lay near or even atop an older, more eroded crater. Finally, laboratory test results place the asteroid impact on Mars at roughly 16 million years ago, clear evidence that the crater in question must be among the freshest visible on the planet. Theoretical models indicate that an object 100 kilometers or larger striking Mars from straight above could have thrown the meteorite, ALH ALH Advanced Light Helicopter ALH Amplitude of Lateral Head (Displacement) ALH Alpha Hospitality Corporation (former stock symbol; now ALHY) ALH Advanced Liquid Hydrogen 84001, off the face of the planet, but no large, round craters in Barlow's database fit the other requirements. Alternatively, a low-angle impact of a much smaller object, creating a distinctively elliptical el·lip·tic or el·lip·ti·cal adj. 1. Of, relating to, or having the shape of an ellipse. 2. Containing or characterized by ellipsis. 3. a. crater, could have done the job. Barlow was preparing to map the craters of origin for the 12 known Martian meteorites Meteorites See also astronomy. aerolithology the science of aerolites, whether meteoric stones or meteorites. Also called aerolitics. astrolithology the study of meteorites. Also called meteoritics. when the news broke about signs of life in one of them. So she focused on ALH84001. The 12 meteorites are considered to be Martian because their chemical signatures match readings taken by the Mars Viking landers in the late 1970s. Only ALH84001, however, is of sufficient age to date from a warmer, wetter, possibly life-supporting era 3.6 billion years ago, scientists say. Barlow's most likely candidate lies in the Sinus Sabaeus region about 14#251# south of the Martian equator. The other candidate, smaller and less elliptical, is at 12#251#S in the Hesperia Planitia region. The famous rock's origin is of great interest to scientists planning to use robots to collect samples during future missions to Mars, says Allan H. Treiman of the Lunar and Planetary Institute The Lunar and Planetary Institute (LPI) is a NASA-funded research institute, dedicated to studies of the solar system, its evolution and formation. The Institute is part of the Universities Space Research Association, located in Houston, Texas. in Houston. Barlow, he adds, "far and away knows the Martian craters better than anyone." |
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