Giant paintballs could be an effective way to redirect any asteroids that may in the future endanger civilization.
The asteroid-deflecting scheme would work primarily through two separate mechanisms. One, mechanically knocking the asteroid off course to a degree; and two, increasing the albedo of the asteroid, and therefore the solar radiation pressure that it is experiencing, further knocking it off course.
“A spacecraft could fire two rounds of pellets full of white paint powder at an asteroid to cover as much of the rock’s surface as possible,” Space.com states.
“The initial force from the paintballs would nudge the asteroid slightly off course. And the pale paint job resulting from the splattered pellets would more than double the space rock’s sunlight reflectivity. More photons bouncing off the asteroid’s surface would enhance solar radiation pressure and bump it further off course.”
The theoretical test was done using the asteroid Apophis as its case study. Apophis is a 900-foot-wide asteroid that is very commonly used in studies because it could potentially impact the Earth within the next few decades. If it does hit the Earth anytime soon, it will likely be in 2029 or 2036.
It would take around five tons of paint to cover the asteroid, according to the calculations of the researchers. And by their estimates, it would take around 20 years for the pressure of the extra solar radiation to push it off its Earth-bound trajectory.
The pellets could also be packed with materials other than paint, such as aerosols. These would “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.”
Lindley Johnson, the program manager for NASA’s Near Earth Objects Observation Program, said that the new proposal was “an innovative variation on techniques used to take advantage of solar radiation pressure.” NASA’s Messenger spacecraft takes advantage of the pressure caused by solar radiation to control its trajectory around Mercury, via solar sails.
“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 in a statement.