A committee of the U.S. National Research Council released a sobering report today on the prospects for defending the home planet against near Earth objects (NEOs), the asteroids and comets that can cross Earth’s orbit and hit us. The prospects aren’t good. Although Congress has mandated a goal of finding 90% of the city-killers—NEOs 140 meters in diameter or larger—by 2020, it hasn’t funded such a search. And at the current rate of funding the NEO threat wouldn’t be sized up for decades.
The committee chaired by geophysicist Irwin Shapiro of Harvard University “was struck by the many uncertainties that suffuse the NEO subject,” according to the report. First there are the uncertainties about the threat. For example, NEOs 30 to 50 meters in size are beginning to appear more dangerous and may—or may not—be striking Earth more frequently than thought.
Ways of fending off NEOs on a collision course with the planet are also poorly understood, essentially untested, and could often pale beside the dreaded nuclear option of blasting them out of the way.
And the most promising search tool in the works—the Large Synoptic Survey Telescope—has not been fully funded and could lose out in the ongoing project prioritization by the astronomy and astrophysics community, notes the report. The list goes on, but at least “the report is honest about the uncertainties,” says NEO researcher Richard Binzel of the Massachusetts Institute of Technology in Cambridge.
The committee’s bottom-line: The NEO threat is real, but the $5 million spent by the United States each year to find and better understand threatening NEOs isn’t going to achieve any measure of safety within the next few decades. It’s up to U.S. political leaders to decide how big a premium should be paid for insurance against a rare but uniquely disastrous impact, the report says. Aside from more money for research into NEOs and ways to deflect them, the report points to two approaches to achieving Congress’s detection goal. Completion of the survey by 2020 would be expensive, requiring a space mission. Cheaper but slower would involve the use of a large ground-based telescope, delaying completion until 2030. Take your pick, says the committee in so many words.
(Image of 18-kilometer wide asteroid Gaspra courtesy NASA.)