Asteroid collision: How to defend Earth, II

and exploding over a sensitive region could be misinterpreted as a nuclear attack by one country on the other — perhaps the first salvo in an all-out attack. India and Pakistan have a few dozen nuclear weapons each; Israel has many more, but is a small country. Iran, when it crosses the nuclear weapons threshold soon, will have very few weapons for a long time. Countries with few weapons, and without an assured second-strike capability, would tend to adopt a use-‘em-or-lose-‘em approach to their nuclear weapons, so an asteroid which is mistaken for a nuclear bomb may well unleash a nuclear retaliation.
Such concerns were one reason why, when NASA found 2008 TC3 in its sights, it not only issued a press release but also alerted the U.S. State Department, military commanders, and White House officials, says Lindley Johnson at NASA headquarters, who oversees the agency’s work on near-Earth objects. “If it had been going down in the middle of the Pacific somewhere, we probably would not have worried too much more about it, but since it was [going to be] on land and near the Middle East, we did our full alerting,” he says.

There is one major way to improve our prospects — point more eyes at the skies, Shiga writes. The European Space Agency wants to get into the monitoring game and may set its telescopes at the European Southern Observatory in Chile on the problem. This could fill a gap in the NASA-funded surveys, which are limited to watching the skies of the northern hemisphere, says Richard Crowther of the U.K. Science and Technology Facilities Council, who is a consultant for ESA and heads a United Nations working group on near-Earth objects.

Be prepared
“Up to now, the U.S. has taken the majority of the responsibility for dealing with this issue and I think it’s time for other states to take on a more equitable share of that,” he says.

Help will also come from two new U.S. observatories designed to survey the entire sky visible from their locations every few days. The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), will consist of four 1.8-meter telescopes, the first of which is already up and running in Hawaii. Plans are afoot to construct the 8.4-meter Large Synoptic Survey Telescope in Chile by 2015, though the project is still raising funds. These will improve the chances of an early detection and potentially extend