 |
 |
||
 |
|
||
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
||||||||
 |
From the Executive DirectorProtecting our planet from dangerous NEOs
|
||||||
Louis D. Friedman Executive Director of The Planetary Society Credit: The Planetary Society Support Research on Planetary Defense
|
January 25, 2010
In the closing days of 2009, the threat to Earth from asteroids unexpectedly rose to the top of world headlines as Anatoly Perminov, director of Roscosmos, the Russian space agency, announced that his top scientists would hold a closed-door meeting to plan a mission to deflect the asteroid Apophis from colliding with Earth in the 2030s.
While I applaud Perminov’s initiative in tackling the inevitable threat from an asteroid impact, the focus on Apophis is misplaced. Close tracking and orbit analysis show that, while in 2029 the asteroid will come closer to Earth than geostationary satellites, and there is a tiny possibility that passage will alter its orbit so that it comes even nearer in 2036, NASA has estimated the probability of an impact at about 1 in 250,000.
Unilaterally planning a mission to an asteroid coming that close to Earth is unwise, and possibly dangerous. If the probability of Apophis hitting Earth is indeed 0.000004, it is not at all obvious that anyone should touch this asteroid at all. A mission to do so might increase the probability of it hitting Earth! Instead of unilateral planning, Russia needs to join with the other spacefaring nations of Earth in a coordinated response to the very real threat of impact.
An international task force could provide reliable information to decision-makers about the probabilities of impact and potential damage and, more crucially, give advice on how to mitigate the threat and even defend against it. A major impact, after all, could affect the entire planet.
Consider this potential danger, which astronaut Rusty Schweickart has called the ìdeflection dilemma.î An asteroid is found to be on a collision course with Earth, heading perhaps straight for Moscow. A mission is launched to deflect it. As its trajectory is changed to miss Moscow, the target point will slowly be dragged across Earth’s surface until it completely misses the planet. But while it is being dragged, the target point could cross a highly vulnerable area -- China, for example. Would the Chinese accept the increased probability of hitting their country while Russia decrease the chance of it hitting Moscow?
The military potential of asteroid deflection becomes obvious, especially since nuclear weapons right now are the only way that governments are prepared to deal with asteroid deflection. With the distrust with which nations often view each other, it would be better to have the responsibility for deflection rest with an international group.
Rusty and his fellow astronauts in the Association for Space Explorers have been leaders in bringing such problems to international attention at the United Nations. The UN Committee on Peaceful Uses of Outer Space has formed an action team on the subject. The Planetary Society has joined the team and we will be working to advance both the research and policy on the danger from NEO impacts. (Members will soon receive a letter about a new planetary defense project the Society is undertaking.)
Then we have our experience in watching the initially calculated odds of an asteroid impact fall as more observations of a newly discovered object show that its trajectory will not cross that of Earth. Don Yeomans of JPL has noted that better calculations of Apophis' path "will almost certainly remove any possibility of an Earth collision" in 2036.
I can understand that decision-makers may not be comfortable or have the luxury of waiting for better calculations. They might feel the need to institute a defense program early. Maybe they should. But the only safe and reliable way to mount a mission to possibly save civilization will be internationally.
Perminov’s new interest is welcome, but I respectfully suggest that the "closed-door meeting," and his comment that "his agency might eventually invite NASA, the European Space Agency, the Chinese space agency and others to join the project," are not appropriate responses. The defense of Earth should be international and open -- right from the beginning.
--Louis D. Friedman
Comments? We welcome your opinions on this subject. Send us email!
[ what is this? ]