UMd-led team finds ancient asteroids formed at solar system's startMarch 24, 2008COLLEGE PARK, Md. -- Using visible and infrared data collected from telescopes on Hawaii's Mauna Kea, a team of scientists, led by the University of Maryland's Jessica Sunshine, have identified three asteroids that appear to be among our Solar System's oldest objects. Evidence indicates that these ancient asteroids are relatively unchanged since they formed some 4.55 billion years ago and are older than the oldest meteorites ever found on Earth, say Maryland's Sunshine and colleagues from the City University of New York, the Smithsonian Institution, and the University of Hawaii. Their findings will be published in this week's edition of Science Express. "We have identified asteroids that are not represented in our meteorite collection and which date from the earliest periods of the Solar System," said Sunshine, a senior research scientist in the University of Maryland's department of astronomy. "These asteroids are prime candidates for future space missions that could collect and return samples to Earth providing a more detailed understanding of the Solar System's first few millions of years." In the Beginning At the beginning of the Solar System, there was just a disk-shaped cloud of hot gas, the solar nebula. When gasses on the edge of the early nebula began to cool, the first materials to condense into solid particles were rich in the elements calcium and aluminum. As the gasses cooled further, other materials also began to condense. Eventually the different types of solid particles clumped together to form the common building blocks of comets, asteroids, and planets. Astronomers have thought that at least some of the Solar System's oldest asteroids should be more enriched in calcium and aluminum, but, until the current study, none had been identified. Meteorites found on Earth do contain small amounts of these earliest condensing materials. As seen in meteorites, these bright white ancient materials, the so-called calcium, aluminum-rich inclusions, or CAIs, can be as large as a centimeter in diameter. Scientists, in fact, long have used the age of CAIs to define the age of the Solar System. "The fall of the Allende meteorite in 1969 initiated a revolution in the study of the early Solar System," said Tim McCoy, curator of the national meteorite collection at the Smithsonian's National Museum of Natural History. "It was at that time scientists first recognized that the remarkable white inclusions -- later called calcium, aluminum-rich inclusions-- which were found in this meteorite, matched many of the properties expected of early Solar System condensates. "I find it amazing that it took us nearly 40 years to collect spectra of these [CAI-rich] objects and that those spectra would now initiate another revolution, pointing us to the asteroids that record this earliest stage in the history of our Solar System," said McCoy. Sunshine and McCoy, with colleagues Harold Connolly, Jr, City University of New York; Bobby Bus, Institute for Astronomy, University of Hawaii, Hilo; and Lauren La Croix, Smithsonian Institution, used the SpeX instrument at the NASA Infrared Telescope Facility in Hawaii to look at the surface of asteroids for evidence of the presence of such early bits of high-temperature rock. In particular, they looked for spectral "fingerprints" indicative of the presence of CAIs. Because different minerals have different reflective properties, the spectrum, or color of light reflected from a surface, reveals information about its composition enabling telescopic compositional analysis. In their paper, Sunshine and colleagues quantitatively compare the spectral signatures of asteroid surfaces and CAIs in meteorites from the Smithsonian's National Museum of Natural History collection. "Several CAI-rich asteroids have been identified that contain 2-3 times more CAI material than any known meteorite," Sunshine said. "Thus it appears ancient asteroids have indeed survived, and we know where they are." University of Maryland |
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| Related Asteroid Current Events and Asteroid News Articles Rosetta bound for outer Solar System after final Earth swingby This morning, mission controllers confirmed that ESA's comet chaser Rosetta had swung by Earth at 8:45 CET as planned, skimming past our planet to pick up a gravitational boost for an epic journey to rendezvous with comet 67P/Churyumov-Gerasimenko in 2014. Follow Rosetta's final Earth boost ESA's comet chaser Rosetta will swing by Earth for the last time on 13 November to pick up energy and begin the final leg of its 10-year journey to comet 67P/Churyumov-Gerasimenko. ESA's European Space Operations Centre will host a media briefing on that day. Clemson researchers say algae key to mass extinctionss Algae, not asteroids, were the key to the end of the dinosaurs, say two Clemson University researchers. Geologist James W. Castle and ecotoxicologist John H. Rodgers have published findings that toxin producing algae were a deadly factor in mass extinctions millions of years ago. A new day dawned fast In 1980, Luis Alvarez and his collaborators stunned the world with their discovery that an asteroid impact 65 million years ago probably killed off the dinosaurs and much of the the world's living organisms. But ever since, there has been an ongoing debate about how long it took for life to return to the devastated planet and for ecosystems to bounce back. Twin Keck Telescopes Probe Dual Dust Disks Astronomers using the twin 10-meter telescopes at the W. M. Keck Observatory in Hawaii have explored one of the most compact dust disks ever resolved around another star. Nullarbor fireball cameras find rare meteorite Using cameras which capture fireballs streaking across the night sky and sophisticated mathematics, a world-wide team of scientists have managed to find not only a tiny meteorite on the vast Nullarbor Plain, but also its orbit and the asteroid it came from. Sharpest views of Betelgeuse reveal how supergiant stars lose mass Using different state-of-the-art techniques on ESO's Very Large Telescope, two independent teams of astronomers have obtained the sharpest ever views of the supergiant star Betelgeuse. Hubble captures rare Jupiter collision The checkout and calibration of the NASA/ESA Hubble Space Telescope has been interrupted to aim the recently refurbished observatory at a new expanding spot on the giant planet Jupiter. Jupiter pummeled, leaving bruise the size of the Pacific Ocean Something slammed into Jupiter in the last few days, creating a dark bruise about the size of the Pacific Ocean. Tiny diamonds on Santa Rosa Island give evidence of cosmic impact Nanosized diamonds found just a few meters below the surface of Santa Rosa Island off the coast of Santa Barbara provide strong evidence of a cosmic impact event in North America approximately 12,900 years ago. More Asteroid Current Events and Asteroid News Articles |
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