Cambridge (Massachussetts), Oct.13 : In research that could aid decisions about future  asteroids on a collision course with Earth, MIT researchers have for the first time determined the composition of a near-Earth asteroid that has a very slight possibility of someday hitting our planet.

That information could be useful in planning any future space mission to explore the asteroid, called Apophis.

And if the time ever were to come when this object or another turned out to be on its way toward an impact on Earth, knowing what it's made of could be one important factor in deciding what to do about it.

"Basic characterization is the first line of defence," says Richard P. Binzel, Professor of Planetary Sciences in the Department of Earth, Atmospheric and Planetary Sciences (EAPS). "We've got to know the enemy."

Binzel presented the new findings this week at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society.

Studying the composition of Apophis has been a useful "practice case," Binzel says, because "you never know when the real one will come along" that is on a collision with the Earth. For determining the composition of a threatening asteroid, Binzel says, "We don't know when the real test will come, but we're ready."

n April 13, 2029, Apophis will come relatively close to Earth (it will miss us by about 22,000 miles). But when it comes by again in 2036, there is a very small possibility - about one chance in 45,000 - that it could be on a collision course.

Binzel, working with EAPS graduate students Cristina Thomas and Francesca DeMeo and others, has been using telescopes on Earth to find out as much as possible about the nature of Apophis and other asteroids.

Short of putting together a space mission that would take years and cost hundreds of millions of dollars, such observations are the best way to find out as much as possible about any space rock that might someday be coming our way, Binzel says.

Using the MIT Magellan telescope in Chile and NASA's Infrared Telescope Facility in Hawaii, they have now been able to figure out exactly what Apophis is made of. (ANI)