Word: asteroids
(lookup in dictionary)
(lookup stats)
Dates: all
Sort By: most recent first
(reverse)
...Asteroids are becoming serious business. Just last month a House subcommittee recommended a threefold increase in spending on observation of near-Earth objects. And only a year after astronomers triggered a short-lived scare by suggesting that asteroid 1997 XF11 might someday strike Earth, another newly discovered asteroid is causing concern. This one is 1999 AN10, a kilometer-wide hulk that in 2027 could hurtle past us as little as 20,000 miles away. First spotted in January, the asteroid attracted little attention when Italian astronomers posted preliminary calculations of its orbit on their website. But when these results were...
...idea that a comet or asteroid might be bearing down on Earth--as in Deep Impact and Armageddon--can be traced to this crusading geologist. Probing Arizona's Meteor Crater in 1956, Shoemaker found a form of quartz that is created only by tremendous impacts. Finding the same telltale mineral in other craters, he concluded that they had been formed not by volcanoes, as most scientists thought, but by large objects hitting Earth. It was only a matter of time, he said, before Earth would be struck again. So he launched the first organized search for big incoming objects, recruiting...
...Luis and Walter Alvarez speculate that an asteroid's crashing into Earth 65 million years ago wiped out the dinosaurs and other species. In 1991 the putative impact crater is found beneath Mexico's Yucatan peninsula...
...four polymer strips designed to bend in response to electrical charges, was barely noticeable. But that force is more than enough for the individual strips to wipe dust from the windshield of a palm-size rover that NASA and the Japanese space agency isas will use to explore an asteroid in 2003. "Clearing dust may not seem like a big deal," says Yoseph Bar-Cohen, a physicist at NASA's Jet Propulsion Laboratory, who created the muscles. But using old-fashioned gears and motors, he says, would make the wiper mechanism "bigger and heavier than the whole rover...
That could change, because the mission to asteroid 4660 Nereus has thrust artificial muscles into the limelight. Whereas human limbs move by contracting and relaxing muscles, Bar-Cohen's artificial variety bends in response to electricity. Apply a charge to one side of a strip, and ions within the polymer are pushed to the opposite side, effectively lengthening one surface while shortening the other...