Scientists find a solar-powered asteroidMarch 08, 2007An international research team led by Academy Research Fellow Mikko Kaasalainen has found an asteroid whose rotation receives an extra kick from solar radiation. The asteroid 1862 Apollo's diameter is about 1.5 km, it has a small moonlet, and its orbit crosses that of the Earth. The team reconstructed Apollo's shape and determined its rotational state using brightness measurements from several years. They found that Apollo's rotation speed steadily increases, and showed that this is due to the re-radiation of solar energy from its surface. The study was published in Nature online on 7 March. Apollo's rotation period is slightly over three hours, and it decreases only by four thousandths of a second per year, so the analysis required accurate mathematical methods. Because of the acceleration, Apollo is likely to break apart or radically change its figure in the future. It may already have done so earlier, and its present moonlet may be a remnant of such a breakup. The study confirms that non-gravitational forces are important in the dynamical evolution of asteroids. Re-radiation of solar energy acts as a propulsion engine on the asteroid's surface. There are two coupled manifestations of this phenomenon: the one changing the orbit (the Yarkovsky effect), and the one changing the spin state (the Yarkovsky-Radzievskii-O'Keefe-Paddack or YORP effect). The study confirmed the latter, and the former was detected by radar in 2003. Non-gravitational orbital and spin changes can be significant or even critical over long time intervals. They affect the motion of asteroids that may collide with the Earth. The phenomenon can also be used to estimate the masses of asteroids. Apollo is now the first object larger than one kilometre across for which the propulsion effect has been detected. Academy of Finland |
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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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