Monday, December 19, 2016

Earth Is Probably Unprepared for a Comet Strike

[The Atlantic] In a beige room on Monday, in the center of a sprawling corporate conference center, lifelong government researchers described one relatively quick and sudden way that the world as we know it could come to an end.
Luckily, they also had a plan to stop it.
For most of human history, “comets were portents of impending catastrophe, not the catastrophe itself,” said Joseph Nuth, a career geochemist at NASA. “That was until [Walter] Alvarez, in 1980, suggested that a comet or asteroid collision could wipe out the various species on the surface of the earth.”
In response to that paper, NASA realized that it was woefully unprepared to fend off a possible asteroid collision. It began tracking 5,000 “potentially hazardous objects,” or PHOs, mostly asteroids. Since more space rocks are discovered every night, the number of “PHOs” now exceeds 700,000, said Nuth.
But NASA—and Earth—remain utterly vulnerable to a comet collision. Unlike asteroids, comets can approach Earth at unusually high speeds as they depart the Oort Cloud, the sphere of icy objects that surrounds the farthest reaches of the solar system.
This means that while NASA might have years or decades to plan for a close-call with an asteroid, a comet could side-swipe Earth only 18 months after it was detected.
So Nuth had a recommendation: The United States should build two comet-destroying spacecraft ahead of time. The first, an “observer” craft, could be launched as soon as a threat is identified. The second, an “interceptor” craft,  could dislodge the asteroid or comet from its orbit or blow it up. Read More