December 30, 2009 | 25
Anatoly Perminov, the head of Russia’s space agency, said today that Russia will consider deflecting the near-Earth asteroid Apophis from its present path, according to news reports. After all, Apophis’s orbit periodically brings the 270-meter asteroid uncomfortably close to Earth, and it has long been on the watch list of nearby bodies that pose a threat (however slight) to Earth. The only problem is that Perminov seems not to have done his homework on the subject.
"A scientist recently told me an interesting thing about the path [of an asteroid] constantly nearing Earth," Perminov told Voice of Russia radio, referring to Apophis, according to the news agency Ria Novosti. "He has calculated that it will surely collide with Earth in the 2030s." (To be fair, it’s worth noting that Perminov’s comments may have been loosely translated or taken out of context.)
While the unnamed scientist may indeed have calculated a future catastrophic impact, many others are on record with less worrisome analyses. In October, near-Earth object (NEO) trackers Steve Chesley and Paul Chodas of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., announced that the revised odds of Apophis striking Earth during its approach in 2036 were about 1 in 233,000. Before that, it had been considered about a 1-in-45,000 shot. In fact, Apophis is currently ranked 0 on the Torino Scale, a measure of the relative hazard associated with near-Earth objects.
According to the Associated Press, Perminov offered few details for remediation of the perceived threat, other than stating that Apophis need not be destroyed. "Calculations show that it’s possible to create a special purpose spacecraft within the time we have, which would help avoid the collision without destroying it (the asteroid) and without detonating any nuclear charges," Perminov said. Many legitimate proposals for deflecting NEOs exist, including brute force tactics such as ramming or detonation as well as gentler, longer-term approaches, such as placing a spacecraft nearby to slowly tug the asteroid or comet onto a safer course through their mutual gravitational attraction.
Perminov is not off base in thinking that near-Earth objects pose a threat. But it is the Apophis-size bodies that have yet to be discovered that we should be focusing on. "The objects that people who have studied the risk from this sort of thing are worried about are the 300-meter class of objects," astronomer Edward Beshore told Scientific American in February. Beshore is principal investigator for what is currently the most prolific NEO-finding program around, the Catalina Sky Survey (CSS) at the University of Arizona. Only a fraction of those bodies, of which there may be tens of thousands, have been catalogued thus far. And without more powerful instruments, Beshore said, it may be decades before astronomers know if Apophis has any truly menacing siblings.
Diagram of Apophis’s orbit: NASA