Asteroids Collide At 11,000 Miles Per Hour; Scientists Study Debris

Asteroids are rocky fragments thought to be debris from the formation and evolution of the solar system approximately 4.6 billion years ago. Millions of them orbit the sun between Mars and Jupiter, in the main asteroid belt. At 70 miles in diameter, Scheila is one of the largest. It orbits every five years, at about three times the Earth’s distance from the sun.

Three days after the outburst was announced, NASA’s Swift Ultraviolet/Optical Telescope (UVOT) captured a spectrum of the asteroid to search for gas but found none. The absence of gas around Scheila led the Swift team to reject alternative scenarios where exposed ice accounted for the activity.

Hubble observations on Dec. 27, 2010, and Jan. 4, 2011, were best explained by a collision with a small asteroid impacting Scheila’s surface at an angle of less than 30 degrees, leaving a crater 1,000 feet across. Jewitt and his colleagues estimated the crash ejected more than 660,000 tons of dust — equivalent to nearly twice the mass of New York’s Empire State Building.

“Previously thought to be beyond the reach of direct observation, collisions are the main process by which asteroids are destroyed and dust is made in the solar system,” said Jewitt, who is a member of UCLA’s Institute for Geophysics and Planetary Physics and lead author of the journal article. “An asteroid collision with the Earth 65 million years ago wiped out the dinosaurs. So, although they’re rare, it’s important to use every example to figure out what happens when two rocks smash together at unimaginable speed.”

The research is illustrated in a NASA-produced video: http://www.youtube.com/watch?v=hwHLYDLEF6g.

Previously, in January 2010, Jewitt’s team used the Hubble Space Telescope to look at the tail of what astronomers thought was an unusual comet but which turned out to be wreckage from the collision of two small asteroids.

NASA’s Goddard Space Flight Center in Greenbelt, Md., manages Hubble and Swift. Hubble was built and is operated in partnership with the European Space Agency. Science operations for both missions include contributions from many national and international partners.

Contacts and sources:

UCLA