Word: orbital
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Dates: during 1990-1999
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...possibility of impact by asteroids with diameters larger than 1 km (3,300 ft.) and impact energies ranging from 100,000 to many millions of megatons, blasts that would have global effects. Though astronomers have found 100 or so of these hulks that can pass through Earth's orbit -- and that might someday pose a threat -- they estimate that there are some 2,000 large "Earth-crossing" asteroids (ECAs) still awaiting discovery...
...within a decade, and virtually all of them in 25 years. And while the survey was hunting its larger prey, it would also spot many of the estimated 300,000 ECAs larger than 100 m (330 ft.), which could cause regional, but not global, disaster. One proposal, to use orbiting sensors and lasers for detecting smaller objects, was rejected by the panel as unneeded, prohibitively expensive and probably futile. Astronomer Gehrels estimates that 100 million asteroids larger than 20 m in diameter are on paths that can cross Earth's orbit. "So," he says "There...
Proceedings at the interception workshop were tumultuous. But there was general agreement about the basic strategy: detect the threatening object and dispatch a warhead-tipped rocket to intercept it and explode, nudging it into a new orbit that would carry it safely past Earth. For a small asteroid detected years and many orbits before its destined collision, the solution would be straightforward. "You apply some modest impulse to it at its perihelion, or closest point to the sun, using conventional explosives," explains Gregory Canavan, a senior scientist at Los Alamos National Laboratory. "The slight deflection that results will amplify during...
Still, the very notion of having high-megaton missiles at the ready, either on Earth or in orbit, was unsettling to many at the workshop, who feared that they could be turned against fellow humans rather than cosmic interlopers. They simply "did not want to talk about very large amounts of energy," says Canavan. "And therefore they wanted to ignore the problem." Some suggested heatedly, in leaks to the press, that pro-nuclear Star Wars scientists, frustrated by the down-sizing of their projects, were using the asteroid and comet threat as an excuse for revitalizing their jobs...
...never found the companion that was so companionable as solitude," wrote Henry David Thoreau. Alas, solitude is getting harder to come by: the Federal Communications Commission has allocated a block of radio frequencies for new satellite paging services. Employing "little low-earth-orbit satellites," such services will allow people to send and receive messages worldwide. Users communicate through calculator-like devices costing around $350. Services could be available...