Selections from Popular Mechanics article...
If you don't typically follow the debate on planetary defense, you could be forgiven for thinking Earth-crushing asteroids are more the stock in trade of big-budget action filmmakers than an actual concern for the taxpaying American. It might surprise you to learn that John Holdren, director of the White House's Office for Science and Technology Policy, recently wrote Congressional leaders to recommend that NASA spearhead a multi-agency effort to assess asteroid-deflection technologies.
But consider, for a moment, the following information regarding asteroids: In the previous 12 years—thanks to enhanced detection—the number of known near-Earth objects (NEOs) has grown from around 500 to upwards of 7000. Of those, approximately 20 percent are potentially hazardous to mankind, meaning that in the coming centuries, they conceivably could collide with the Earth.
But there's more, says former astronaut and PM editorial advisor, Tom Jones, who recently co-chaired a NASA Advisory Council task force on the subject of defending our planet from such calamitous celestial bodies.
"Remember, there are probably a million near-Earth asteroids out there that can come all the way through the atmosphere should they strike us," Jones says. "Twenty percent of a million is 200,000. So we have 200,000 potentially city-busting near-earth asteroids out there, and we know of only a tiny fraction of them."
With these frightening realities in mind, the eight-member Ad Hoc Task Force on Planetary Defense recommended ways in which NASA may address the threat of an NEO impact. Primary among them is establishing a Planetary Defense Coordination Office to begin in earnest the task of sifting through the options—strategies that currently include using a small spacecraft, called a gravity tractor, to pull an asteroid off-track; impacting it with a somewhat larger craft to knock it off course; and detonating a nuclear weapon near its surface to vaporize soil, propelling it in another direction.
Increasing the rate of discovery requires upgrades: Collaborating with the Air Force's Pan-STARR Telescope in Hawaii and the proposed Large Synoptic Survey Telescope (LSST) would be a good start. The task force also advocates launching a new space-based telescope. For about the cost of a typical NASA planetary mission, around $500 million, a tailor-made telescope would survey space for as-yet-unknown NEOs, potentially eliminating the mystery of what else is up there (and headed for us) in its first five years of operation.
Joe P. Hasler
12 November 2010
Popular Mechanics
Link: Article
No comments:
Post a Comment