Original URL: http://www.theregister.co.uk/2012/10/26/paintball_defense_against_asteroid_striking_earth/

Paintballs proposed as defense against ASTEROID ATTACK

Just in time to to deflect Apophis, destroyer of worlds

By Rik Myslewski

Posted in Science, 26th October 2012 23:38 GMT

An MIT graduate student has devised a plan to save the world from destruction by an inbound asteroid using a novel weapon: interplanetary paintballs.

Sung Wook Paek of the Cambridge, Massachsetts, brainiac academy's Department of Aeronautics and Astronautics – affectionately known as AeroAstro – entered his asteroid-deflecting proposal in the Move An Asteroid 2012 Competition sponsored by the United Nations Space Generation Advisory Council (SGAC). He won.

Paek's plan eschews the asteroid-killing nuclear explosives of Armageddon, Deep Impact, The Day the Sky Exploded, and Meteor, or even the frickin' lasers of Asteroid, and relies instead on a more prosaic means to nudge an asteroid off course: paint.

The boffin-in-training envisions maneuvering a spacecraft close to the incoming earth destroyer, then firing off two volleys of paint pellets, the first to cover one half of the asteroid in a light-colored paint powder, and the second to do the same to the other side after it rotated into view.

With the asteroid thus brightened – or, more properly, thus having its albedo increased – the sun's solar radiation would more forcefully push upon it, knocking it off course using esentially the same principle that won the University of Queensland's Mary D'Souza the 2008 SGAC prize: turning the asteroid into a solar sail.

As anyone who has stood in the sun wearing a black T-shirt knows, dark surfaces absorb the sun's rays, while said rays bounce off light surfaces. And as Reg readers certainly remember from their study of Newtonian physics, when something bounces off something, the first something gives the second something a push. The asteroid would be slowly but steadily nudged away, saving our beloved planet.

Speaking of Newton's Third Law of Motion, the paint pellets themselves would also have a kinetic effect on the asteroid's course when fired upon it, adding to the trajectory-altering effect. Bonus!

Being a thorough young student, Paek tested his hypothosis by mathematically modelling what would be required to deflect the asteroid Apophis, which is scheduled to swing by our neighborhood in 2029 and again in 2036.

For those of you who haven't been following that brute's perigrinations for the past decade or so, Apophis has a diameter of about 1,480 feet (450 meters) and is calculated to have a mass of about 27 gigatons – that's US tons, by the way, not metric tons. Should Apophis drop in for a visit, the results wouldn't be pretty.

According to Paek's slide rule (or more likely his copy of Maple), a mere five tons of paint would be needed to coat Apophis with a five-micrometer layer of paint powder. It would then take up to 20 years for the force of solar radiation to push Apophis sufficiently off course, saving our earthly hineys.

Quick. Look at the calendar. Ah, relax – we still have time before the 2036 visit. The 2029 one? Worry not – that pass will merely be close enough to deflect Apophis enough to give it a better shot at us in 2036 – although the odds of it actually doing so are quite poor.

That latter year, however, will be a presidential election year in the US – and if political advertising has increased to a Minority Report level of sophistication by that time, we may be begging Apophis to put us out of our misery. ®