Apophis, a 1,600-foot-wide asteroid, has a one in 250,000 chance of hitting Earth in 2036, creating a real-life Armageddon situation. But scientists are not taking any chances in assuming the odds are in our favor.
Though the asteroid is expected to pass Earth in 2029, it could enter a gravitational keyhole, which could send it back towards Earth with the potential for impact in 2036. According to Technology Review, keyholes are small — the one in question being 600 meters wide — so deflecting the asteroid just a touch would be enough to send it off course and ensure it doesn’t come back toward Earth seven years later.
The European Space Agency and Chinese researchers have independently announced plans to begin testing methods of asteroid deflection. Scientists at both European Space Agency and Tsinghua University in Beijing believe that spacecraft collision with the asteroid is the best way to set it off course.
The European Space Agency will test its technique against a real asteroid in 2015 in a mission called Don Quijote. Don Quijote involves two spacecrafts. One, called Hidalgo, will impact the asteroid at a speed of six miles per second while the other (Sancho) will orbit the asteroid before and after collision collecting data and analyzing just how far off course the impactor spacecraft threw the asteroid.
Watch the European Space Agency’s simulation here:
Similarly, the Chinese researchers propose hitting the asteroid with a spacecraft, but the method of getting there is a bit different. They propose using a solar sail (a form of spacecraft propulsion) to send the spacecraft into retrograde orbit and on a collision course with the asteroid. Technology Review has more on this technique:
Putting a spacecraft into a retrograde orbit about the Sun using little or no fuel is a pretty neat trick by anyone’s standards.. The Chinese team’s calculations demonstrate the point. They show that a 10 kg sail in retrograde orbit, that hits Apophis a year before 2029, would deflect it enough to miss the keyhole, thereby eliminating the chance that the asteroid will return in 2036.
And such a mission ought to be relatively cheap and relatively easy to deploy.
That sounds easy enough. In practice, however, threading this camel through the eye of a needle will be extremely tricky. There are all kinds of variations in the solar wind that could send such a spacecraft wildly off course.
As PC World points out, these collision techniques may not be as Hollywood-worthy as the nuclear warheads of Armegeddon, but with a few years to experiment, refine and (hopefully) collaborate, the asteroid will hopefully be diverted and not directed back toward us.