Close encounter with asteroid

The Near-Shoemaker spacecraft has spent eight months in orbit around Eros

The Near-Shoemaker spacecraft has passed within 5 km (3 miles) of the Eros asteroid - its closest encounter yet.

The spacecraft skirted the rocky surface of the asteroid in a daring fly-by and sent back dramatic pictures.

One close image of Eros shows rocks of all sizes and shapes, but the floors of some craters are smooth, suggesting the accumulation of fine dust.

The space probe made history eight months ago by becoming the first spacecraft to orbit an asteroid.

Close and dangerous

"The manoeuvre succeeded and we are now in low orbit," said Helen Worth of John Hopkins University in Maryland, US. The team manages the mission on behalf of the American space agency Nasa.

Near-Shoemaker took photographs of Eros while it passed close to the space rock for around 30 minutes. The images are three or four times more detailed than earlier ones.

Near has already detected traces of magnesium, silicon and aluminium on the surface of the potato-shaped asteroid, which is twice the size of the island of Manhattan in New York.

The mission is designed to answer fundamental questions about the many asteroids and comets which come close to Earth's orbit. It may contain clues about how the Earth and other planets were formed.

Higher orbit

Wrapping up a busy day, the Near-Shoemaker spacecraft fired its thrusters and headed for a higher orbit.

A three-minute engine burn lifted the spacecraft from a low-altitude orbit toward a more stable position 200 km (125 miles) from the centre of the asteroid. The burn was the longest since Near-Shoemaker first began orbiting Eros.

"Had we stayed there, the low orbit could have brought the spacecraft dangerously close to the asteroid," said Dr Robert Farquhar, Near's mission director.

"When you make a close pass like that the gravity field affects the spacecraft a lot more than it would otherwise, so we helped it along with a manoeuvre."

Best yet

The Near team has just started to sift through the close-ups the digital camera snapped during the flyover.

"We've never seen the surface of an asteroid or planetary satellite at this high resolution without actually landing," said Dr Scott Murchie, Near imaging team member.

"What strikes me most about the pictures is the diversity in the sizes and shapes of the rocks.

"When we analyse these high-resolution images in more detail, we'll learn something about the processes that have shaped the surface of Eros."