Word: orbits
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...punish Beijing for the massacre of students in Tiananmen Square, Senator Al Gore sponsored legislation barring U.S.-made satellites from being launched on Chinese rockets--unless the President declared such a launch to be in the national interest. Under pressure from American corporations desperate to get their satellites into orbit, Bush issued nine such waivers between 1989 and 1992--and Gore denounced him as "an incurable patsy." But after Clinton was elected President, he came under the same pressure from business leaders, who argued that the export controls endangered America's telecommunications primacy. Clinton began signing the same waivers (there...
...billion-apiece KH-12 satellites the Pentagon has in orbit are like Hubble space telescopes pointed back to earth. From 164 miles up, their optical sensors can snap clear photographs of objects no larger than a paperback novel on the ground. The two Lacrosse satellites, same price tag, with solar-power panels that stretch the length of half a football field, have radar-imaging cameras that can see through clouds and even the dust storms that swirl around India's Pokhran test site. In a crisis, at least one of the four birds can be positioned over a target...
Almost as worrisome are the estimated 300,000 asteroids larger than 300 ft. wide that also come perilously near or intersect Earth's orbit; each could inflict Tunguska-like damage over a large region. The number of Earth-crossing asteroids larger than 60 ft. across, says University of Arizona astronomer Tom Gehrels, could be as high as 100 million. A hit by any one of them could destroy a large city...
What if one or more of these asteroids are found to be a serious threat? Scientists generally agree on the best strategy for avoiding disaster: launch a rocket to intercept the intruder and, at the very least, change its orbit. If the asteroid is small and detected many years and orbits before its predicted impact, the solution would be straightforward. "You apply some modest impulse to the asteroid at its closest approach to the sun," says Los Alamos' Canavan. "The slight deflection that results will amplify during each orbit, ensuring that the asteroid misses Earth by a wide margin." That...
...detected late in the game, however, nuclear weapons may well be the only answer. If XF11 had been discovered only 90 million miles away and on a beeline toward Earth, for example, the equivalent of a 1-megaton explosion would have been necessary to shove it into a safe orbit. Had it first been spotted at just a tenth of that distance, a 100-megaton blast would have been needed to turn it away...