Artist's illustration depicts the breakup of a large asteroid producing fragments large enough to wipe out the dinosaurs in a collision with the Earth. Image Credit/NASA illustration
Scientists involved in NASA’s Wide-field Infrared Survey Explorer, or WISE , mission may have cleared a suspect in what is perhaps one of the Earth’s greatest mysteries.
What was the source of the giant asteroid that smacked into the Earth 65 million years ago, wiping out the dinosaurs and other forms of life?
New evidence suggests the Baptistina family of asteroids are not the guilty party, NASA announced on Monday.
The Baptistinas fell under suspicion four years ago among astronomers using ground-based telescopes. The theory that emerged from the 2007 observations suggested that 160 million years ago the large asteroid Baptistina was pounded by another object in the main asteroid belt between Mars and Jupiter.
One mountain-sized fragment scattered by the collision careened towards the Earth, snuffing out the lumbering reptiles.
NASA's WISE space telescope surveyed the skies in the infrared. Image Credit/NASA illustration
Launched in late 2009 on a multi-purpose mission, WISE twice surveyed the sky in the infrared between January 2010 and February 2011 under the guidance of NASA’s Jet Propulsion Laboratory.
The asteroid-hunting portion of the mission, called NEOWISE, used the data to catalogue more than 157,000 asteroids in the main belt and discovered more than 33,000 new ones.
In the Baptistina case, WISE provided some subtle detective work.
Visible light reflects off an asteroid, furnishing one means of gauging the size of the rocky objects. However, without knowing how reflective the surface of the asteroid is, it’s difficult to accurately estimate the size.
Infrared observations carried out with WISE permitted more accurate estimates. The infrared light is radiated rather than reflected by the asteroid itself, offering a more accuracy.
Together, IR and visible-light observations provide even better accuracy.
In all, WISE mission scientists measured the reflectivity and the size of about 120,000 asteroids in the main belt, including 1,056 members of the Baptistina family. They concluded the original parent Baptistina asteroid actually broke up closer to 80 million years ago, not the 160 million that was originally believed.
The size and reflectivity of the Baptistinas also permit scientists to calculate how much time would have been required to reach their current locations. Larger fragments would not scatter as quickly as the smallest.
The findings suggest the original suspects simply did not have the time required to settle into orbits where they could be gravitationally nudged towards the Earth by giant Jupiter or Saturn, scientists responsible for the studies concluded.
“As a result of the WISE science team’s investigation, the demise of the dinosaurs remains in the cold case files,” said Lindley Johnson, program executive for the Near Earth Object (NEO) Observation Program at NASA Headquarters inWashington.
The findings continue to suggest the Earth was impacted by a six to seven-mile wide asteroid 65 million years ago, but one unrelated to the Baptistina family.