WASHINGTON -- Space scientists are squaring off with asteroid Eros.
The Near Earth Asteroid Rendezvous (NEAR) spacecraft has eyed unusual square craters on Asteroid 433 Eros, about 109 million miles (176 million kilometers) from Earth.
The NEAR photo find suggests that the space rock is riddled with a system of faults, fractures and cracks. Such craters, scientists say, offer new clues to the age and history of Eros.
"There are weird-shaped craters on Eros. It's turned out to be a very complex place," said Olivier Barnouin-Jha, a crater expert on the NEAR project at the Applied Physics Laboratory (APL) in Laurel, Maryland.
APL built the NEAR, which was launched in February 1996, and serves as mission control for the asteroid-surveying spacecraft.
Barnouin-Jha told SPACE.com that the odd-shaped craters appear to have been formed within preexisting faults on Eros. As the craters were created, those faults served to contain the shock wave resulting from the explosive smacks into Eros' surface, he said.
Square pegs and round holes
Eros is not the only solar system body to have square holes amid round craters.
"We've actually seem them before. They are usually seen with smaller craters. They've been observed on the moon, although for different reasons. We're seeing a lot more of these with the new Mars Global Surveyor data as well, Barnouin-Jha said.
Here on Earth, stamped into the desert near Winslow, Arizona, is the Barringer Meteor Crater. Created some 50,000 years ago, its rim takes on a square-shaped look due to fractured terrain around the impact site.
On Eros, sightings of squared-off craters are on the rise.
"There are numbers of these craters. Once you start looking you see more and more of them," Barnouin-Jha said.
The NEAR probe now orbiting Eros has pegged the asteroid to be a consolidated body, but with a ubiquitous fabric of ridges and grooves. That suggests that Eros might have an extensively fractured interior.
Playing the cratering record
Barnouin-Jha said that studies of Eros' craters show that the asteroid is quite strong. "Gravity is not playing a very large role at all in controlling cratering on Eros," he said.
That is consistent with the bigger picture, that the asteroid is peppered with loads of faults, through and through. Yet Eros is not a broken rubble pile, Barnouin-Jha said.
"I think we're going to learn about cratering history, the evolution of Eros, and I think of asteroids in general," he said.
Picture palace
The NEAR spacecraft has been circuiting Eros since February. It is now flying in a 62-mile (100-kilometer) circular orbit above the asteroid's surface.
A low-altitude flight -- down to within 3 miles (5 kilometers) of the surface -- is slated for NEAR on October 25.
Louise Prockter, member of the NEAR imaging team at APL, said "we're overwhelmed with images" of Eros.
About 105,000 pictures have been relayed to Earth. Given all those Eros pictures of the "hard-body" asteroid, there never is a dull moment, Prockter said.
"I can definitely say that's never the case. There's something every day that comes in that we haven't seen before that is really cool," she said.
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