Artist's view of asteroid Apophis. Credit: European Space Agency
An incoming asteroid with Earth’s name on it…what to do is a constant concern of Near Earth Object experts.
How about a volley or two of space-launched paintballs?
Sung Wook Paek, a graduate student in MIT’s Department of Aeronautics and Astronautics, says if timed just right, pellets full of paint powder, launched in two rounds from a spacecraft at relatively close distance, would cover the front and back of an asteroid, more than doubling its reflectivity, or albedo.
The initial force from the pellets would bump an asteroid off course. And over time, the Sun’s photons would deflect the asteroid even more.
The solar radiation pressure — the force exerted on objects by the Sun’s photons – would ever-so-slightly nudge the object, thus altering its course.
Cumulative effect
As the pellets hit the asteroid’s surface, they would burst apart, splattering the space rock with a fine, five-micrometer-layer of paint.
However, taking this action against a hazardous-to-Earth asteroid takes time.
From his calculations, Paek estimates that it would take up to 20 years for the cumulative effect of solar radiation pressure to successfully pull the asteroid off its Earthbound trajectory.
Other methods have included detonating a nuclear bomb near an asteroid or using spacecraft as “gravity tractors,” that is, using a vehicle’s gravitational field to pull an asteroid off its path.
Five tons of paint
Paek’s anti-asteroid paintball strategy won the 2012 “Move an Asteroid Technical Paper Competition,” sponsored by the United Nations’ Space Generation Advisory Council, which solicits creative solutions to space-related problems from students and young professionals.
Paek presented his paper at the recently held International Astronautical Congress in Naples, Italy.
In his proposal, Paek used the asteroid Apophis as a theoretical test case.
According to astronomical observations, this 27-gigaton rock may come close to Earth in 2029, and then again in 2036. Paek determined that five tons of paint would be required to cover the massive asteroid, which has a diameter of 1,480 feet.
Check out this MIT video to see how this tactic would work:
http://www.youtube.com/watch?v=auSr_aO_gRo
By Leonard David based on Jennifer Chu, MIT News Office release.