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Paintballs may save the world from incoming asteroids

October 29, 2012 6:29pm
Paintballs may turn out to be an unlikely savior for the Earth against the danger of incoming asteroids, a Massachusetts Institute of Technology (MIT) graduate student has suggested.
MIT Department of Aeronautics and Astronautics graduate student Sung Wook Paek said that with proper timing, pellets with paint powder can do the trick.
“The initial force from the pellets would bump an asteroid off course; over time, the sun’s photons would deflect the asteroid even more,” the MIT said.
Paek presented his paper this month at the International Astronautical Congress in Naples, Italy, MIT said.
It added Paek’s paper on this strategy won the 2012 Move an Asteroid Technical Paper Competition, sponsored by the United Nations’ Space Generation Advisory Council.
Previously, scientists had proposed a wide variety of methods to avoid an asteroid collision, including a projectile or spacecraft to collide with an incoming asteroid.
Other methods included detonating a nuclear bomb near an asteroid or using spacecraft as “gravity tractors,” using the craft’s gravitational field to pull an asteroid off its path.
NASA Near Earth Objects Observation Program manager Lindley Johnson described Paek’s proposal as “an innovative variation” on a method used by others to capitalize on solar radiation pressure.
MIT noted MESSENGER, a spacecraft orbiting Mercury, has solar sails that propel the craft with solar radiation pressure, thus requiring less fuel for propulsion.
“It is very important that we develop and test a few deflection techniques sufficiently so that we know we have a viable ‘toolbox’ of deflection capabilities to implement when we inevitably discover an asteroid on an impact trajectory,” Johnson said.
William Ailor, principal engineer for Aerospace Corp. in El Segundo, California, added the potential for an asteroid collision is a long-term challenge for scientists and engineers.
“It’s nice that we’re getting young people thinking about it in detail, and I really applaud that,” he said.
Paintball strategy
Paek’s paintball strategy was based on a solution submitted by last year’s competition winner, who proposed deflecting an asteroid with a cloud of solid pellets.
He added paint to the pellets to exploit solar radiation pressure, the force exerted on objects by the sun’s photons.
Researchers have observed that pressure from sunlight can alter the orbits of geosynchronous satellites, while others have proposed equipping spacecraft with sails to catch solar radiation.
Paintballs in space
Paek’s proposal cited the asteroid Apophis, a 27-gigaton 1,480-foot-diameter rock that may pass near Earth in 2029 and 2036, as a theoretical test case.
He theorized five tons of paint would be needed to counter the threat, timing a first round of pellets to cover the asteroid’s front, and a second to cover its backside.
When the pellets burst, they would theoretically cover the asteroid with a five-micrometer layer of paint.
Paek calculates it may take up to 20 years for cumulative solar radiation pressure to pull the asteroid out of its trajectory toward Earth.
On the other hand, he said rockets may be impractical to launch the pellets, suggesting instead that the paintballs be made in space such as the International Space Station.
Aerosols, alternatives
Paek also suggested that instead of paint, the capsules could be filled with aerosols that could “impart air drag on the incoming asteroid to slow it down.”
“Or you could just paint the asteroid so you can track it more easily with telescopes on Earth. So there are other uses for this method,” he said. — TJD, GMA News

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