Researchers found a rapidly spinning asteroid is held together by forces called van der Waals, which have never been detected before on this type of object. The findings could help protect Earth from future collisions.
University of Tennessee, Knoxville researchers found asteroid 1950 DA rotates so quickly it defies gravity. Past research has shown asteroids are loose piles of rubble that have been held together by gravity and friction, but the team determined the asteroid is spinning so quickly it defies these forces. The team made their finding by looking at thermal images and orbital drift to calculate thermal inertia and bulk density; they detected cohesive forces in an environment with very little gravity.
"We found that 1950 DA is rotating faster than the breakup limit for its density," said Ben Rozitis, a postdoctoral researcher. "So if just gravity were holding this rubble pile together, as is generally assumed, it would fly apart. Therefore, interparticle cohesive forces must be holding it together."
The rotation of the asteroid is so fast its equator experiences negative gravity, meaning if an astronaut tried to stand on it they would fly off into space. The presence of these cohesive forces have been predicted in small asteroids, but evidence of its existence has never been seen before. The findings could help researchers gain insight into how to better protect the Earth from asteroid impacts.
"Following the February 2013 asteroid impact in Chelyabinsk, Russia, there is renewed interest in figuring out how to deal with the potential hazard of an asteroid impact," Rozitis said. "Understanding what holds these asteroids together can inform strategies to guard against future impacts."
The research reveals some potential techniques, such as a kinetic impactor, could destroy objects hurtling towards Earth but in the long run would break them up into smaller more-dangerous asteroids.
"With such tenuous cohesive forces holding one of these asteroids together, a very small impulse may result in a complete disruption," Rozitis said.
