Asteroid 2012 DA14 will buzz within 17,200 miles of Earth – a record for a known object of that size. While it's no threat to hit, it might help scientists find and track others that are.
Asteroid 2012 DA14 is on course to buzz Earth Friday, making its closest approach at 2:24 p.m. Eastern Standard Time.
The object, roughly 150 feet across, poses no threat to Earth. But its close approach, which will bring it to within 17,200 miles of the planet, is a record for a known object of that size.
Coming so close, the asteroid represents a prime target for scientists who are interested in the object for scientific reasons as well as to improve their abilities to forecast asteroid orbits as a way to keep tabs on potentially hazardous objects.
Factors that influence those orbits can be subtle, notes Ed Beshore, an astronomer at the University of Arizona at Tucson and a key player in NASA's upcoming OSIRIS-Rex mission to asteroid 1999 RQ36. The launch is slated for 2016.
For instance, when sunlight hits the surface of an rotating asteroid, the asteroid returns that energy to space in the form of heat.
"The heat acts like a tiny rocket thruster that can push asteroids out of otherwise harmless orbits," he says. The reason: A rotating asteroid sheds the heat unevenly across its surface, in effect sloughing it off in the direction of "dawn" on the asteroid. This direction may or may not coincide with the direction the asteroid is traveling along its orbit.
Indeed, this force, known as the Yarkovsky effect, is thought to help resupply the inner solar system with asteroids that otherwise might have stayed in the main asteroid belt, which lies between Mars and Jupiter.
A year ago, Dr. Beshore says, one of the mission's team members performed "a really exquisite set of measurements using radar data and came up with a preliminary estimate for the kinds of forces" this effect imposes on OSIRIS-Rex's target asteroid.
It's about the same as "the force that you feel when you hold a couple of grapes in your hand, he says, adding "that force, applied over millions of years, can literally move these mountains of rock around."