spacetoday.net: Cohesive forces hold together rapidly spinning small asteroid

Posted: Fri, Aug 15, 2014, 8:34 AM ET (1234 GMT)
Radar image of asteroid 1950 DA (NASA)

A near Earth asteroid that is spinning at a rate higher than thought possible is kept from flying apart by cohesive forces, scientists said this week. The asteroid, 1950 DA, is believed to be a "rubble pile" asteroid based on its density: a conglomeration of rockets held together by self-gravity. Such an asteroid, though, would fly apart if its rotational period was shorter than 2.2 hours, but observations indicated its period was 2.1 hours. Scientists believe that van der Waals force, a weak cohesive force between molecules that also allows geckos to climb walls. If such an asteroid was on a collision course with the Earth, techniques to deflect it like kinetic impactors could instead cause it to break into several smaller pieces on similar trajectories.