September 19, 2011
Dinosaur Killer Remains At Large
NASA said on Monday that the family of asteroids believed to be responsible for the destruction of dinosaurs is innocent.Observations made by NASA's Wide-field Infrared Survey Explorer (WISE) confirmed that a 2007 study's claims that a huge asteroid known as Baptistina destroyed the dinosaurs was false.
Although the new discovery has abolished one theory of how the dinosaurs ceased to exist, it did not bring about any new theories on the topic.
The original theory used visible-light data from ground-based telescopes to suggest that Baptistina crashed into another asteroid in the main belt between Mars and Jupiter about 160 million years ago.
This collisions allegedly sent shattered pieces of asteroids as big as mountains, one of which was believed to have impacted Earth and caused the dinosaur extinction.
However, observations made by WISE using infrared light from January 2010 to February 2011 left the mystery still pondering what happened.
"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," Lindley Johnson, program executive for the Near Earth Object (NEO) Observation Program at NASA Headquarters in Washington, said in a statement. "With infrared light, WISE was able to get a more accurate estimate, which throws the timing of the Baptistina theory into question."
The team measured the size and reflectivity of the asteroid family members, which helped indicate how much time would have been required to reach their current locations.
The results revealed a chunk of the original Baptistina asteroid would have needed to hit Earth in less time than previously throughout to cause the extinction of the dinosaurs.
"This doesn't give the remnants from the collision very much time to move into a resonance spot, and get flung down to Earth 65 million years ago," Amy Mainzer, a study co-author and the principal investigator of NEOWISE at NASA's Jet Propulsion Laboratory (JPL) in Pasadena. California, said in a press release.
"This process is thought to normally take many tens of millions of years." Resonances are areas in the main belt where gravity nudges from Jupiter and Saturn can act like a pinball machine to fling asteroids out of the main belt and into the region near Earth.
What exactly destroyed the dinosaurs 65 million years ago still remains a mystery, but scientists are still determined to find the culprit.
"We are working on creating an asteroid family tree of sorts," Joseph Masiero, the lead author of the study, said in a statement. "We are starting to refine our picture of how the asteroids in the main belt smashed together and mixed up."
Image Caption: This artist's concept shows a broken-up asteroid. Image credit: NASA/JPL-Caltech
On the Net:
- More information is online at http://www.nasa.gov/wise , http://wise.astro.ucla.edu/ and http://jpl.nasa.gov/wise .