Baptistina Asteroid Not Responsible For Dinosaur Extinction

From International Business Times: Baptistina Asteroid Not Responsible For Dinosaur Extinction
Recent observations from NASA's Wide-field Infrared Survey Explorer (WISE) mission suggest that the family of asteroids thought to be responsible for the dinosaurs' extinction 65 million years ago may not have been the culprit.

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 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.

Since this scenario was first proposed, evidence developed that the so-called Baptistina family of asteroids was not the responsible party. With the new infrared observations from WISE, astronomers say that Baptistina may finally be ruled out.

"As a result of the WISE science team's investigation, the demise of the dinosaurs remains in the cold case files," NASA's Near Earth Object (NEO) Observation Program executive Lindley Johnson said. "With infrared light, WISE was able to get a more accurate estimate, which throws the timing of the Baptistina theory into question."

The scientists credit advanced technology for the ability to reach this conclusion. WISE's predecessor was the Infrared Astronomical Satellite. WISE is hundreds of times greater in terms of sensitivity.

WISE surveyed the entire celestial sky twice in infrared light from January 2010 to February 2011. The asteroid-hunting portion of the mission, called NEOWISE, used the data to catalog more than 157,000 asteroids in the main belt and discovered more than 33,000 new ones.

Visible light reflects off an asteroid. Without knowing how reflective the surface of the asteroid is, it's hard to accurately establish size. Infrared observations allow a more accurate size estimate. They detect infrared light coming from the asteroid itself, which is related to the body's temperature and size. Once the size is known, the object's reflectivity can be recalculated by combining infrared with visible-light data.

Calculations showed that the Baptistina parent asteroid only broke up around 80 million years ago that means the remnants had only 15 million years to get flung down to Earth 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. This process is thought to normally take many tens of millions of years," said study co-author Amy Mainzer at NASA's Jet Propulsion Laboratory in California in the release.

The asteroid family that produced the killer rock remains at large. Scientists are reconstructing positioning data in search of an asteroid about 6.2 miles (10 kilometers) in diameter that smashed into Earth, leaving a massive crater-shaped impact basin in the Gulf of Mexico and meteorite-type minerals in the fossil records, Discovery News reported.

"We are working on creating an asteroid family tree of sorts," lead author Joseph Masiero said in a NASA statement. "We are starting to refine our picture of how the asteroids in the main belt smashed together and mixed up."