Planetary securityNew ideas for deflecting Earth-threatening asteroids
As scientists use better equipment to make more accurate observations of space, they find more Earth-threatening objects loitering in Near Earth Orbit; a debate is growing as to the best method to deal with this threat
There is a growing recognition of the risk to Earth posed by asteroids. This growing recognition is the result of new knowledge, gained from new and better observation equipment, of just how many Earth-threatening objects there are out there in space. These were the conclusions, for example, of a committee that the National Academy of Sciences created at Congress’s request to examine this issue. The academy panel was headed by Irwin Shapiro, a former director of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. The panel had a two-part assignment from Congress: Detect and deflect asteroids that might hit Earth.
First, the Shapiro committee was supposed to propose the best way to detect and analyze 90 percent of the so-called “near Earth objects” (NEOs) orbiting between Mars and Venus that are wider than 460 feet by 2020. About 20 percent of these are identified as potentially hazardous objects because they might pass within 5 million miles of Earth (20 times the distance to the Moon). More than 5,000 near Earth objects, including 789 potentially hazardous objects, have been identified so far. Lindley Johnson, the manager of NASA’s asteroid detection program, told the committee that future surveys will find at least 66,000 near Earth objects and 18,000 potentially hazardous objects (see 26 November 2008 HS Daily Wire). A collision with one or more of these many objects littering the solar system is inevitable, Johnson said. “Once every hundred years there might be something to worry about, but it could happen tomorrow.”
Talking about disasters that do not announce themselves: astronomers had only twenty-four hours’ notice of a small asteroid that blew up over northern Africa on 7 October (see 10 October 2008 HS Daily Wire). A larger, more dangerous object presumably would be spotted years or decades ahead, giving humans time to change its course before it hit.
There are several methods being considered for deflecting asteroids hurtling toward Earth (to learn more about the Shapiro panel’s ideas about deflecting threatening asteroids, see “Scientists Seek Ways to Ward Off Killer Asteroids,” 22 December 2008 HS Daily Wire). We could blast the asteroid with a nuclear bomb, but that would risk shattering it into smaller pieces that could still threaten Earth. Others suggest trying to force an asteroid off course by slamming into it with a heavy object, but this is an unproven and, therefore, risky technique. New Scientist’s David Shiga writes that now there may be a
