The asteroid once considered responsible for the extinction of the dinosaurs could not have been the cause, observations from NASA's Wide-field Infrared Survey Explorer telescope show.

In its report, NASA scientists maintained the currently widespread belief that a large meteor crash 65 million ago did cause the dinosaurs' extinction. The report simply casts doubt on a 2007 theory that cited the giant Baptistina asteroid as a possible suspect.

The team measured the reflectivity and size of about 120,000 asteroids in the main belt, including 1,056 members of the Baptistina family, and calculated that the original parent Baptistina asteroid actually broke up closer to 80 million years ago, half as long ago as originally proposed.

The results revealed that a chunk of the original Baptistina asteroid needed to hit Earth in less time than previously believed, in just about 15 million years, to cause the extinction of the dinosaurs.

The 2007 study using visible-light data from ground-based telescopes suggests that Baptistina crashed into another asteroid in the main belt between Mars and Jupiter about 160 million years ago. This collision supposedly sent shattered pieces of asteroids as big as mountains, one of which was believed to have hit Earth and caused the dinosaur extinction, according to a NASA release.

As a result of the WISE science team's investigation, the demise of the dinosaurs remains in the cold case files, says Lindley Johnson, program executive for the Near Earth Object Observation Program.

The original calculations with visible light estimated the size and reflectivity of the Baptistina family members, leading to estimates of their age, but we now know those estimates were off. With infrared light, WISE was able to get a more accurate estimate, which throws the timing of the Baptistina theory into question.

The NEOWISE data captured from January 2010 to February 2011 will help to disentangle asteroid families that overlap and trace their histories. We are working on creating an asteroid family tree of sorts, said Joseph Masiero, the lead author of the study.

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