Plug pulled on asteroid probe

Near-Shoemaker survived touchdown on asteroid Eros

By BBC News Online science editor Dr David Whitehouse

The American space agency Nasa is hanging up the line to the Near-Shoemaker spacecraft that landed on the asteroid Eros on 12 February.

Near-Shoemaker, the first mission in Nasa's Discovery programme of "faster, better, cheaper" space missions, and the first to land on an asteroid, has delighted astronomers.

"Near-Shoemaker has raised the bar," said Dr Stamatios Krimigis, of Johns Hopkins University, US, where the probe was built and operated.

But with signs that Near-Shoemaker's sensors are failing and with increasing difficulties in maintaining communication with the probe, Nasa has decided to pull the plug.

Soft touch

"This mission has been successful far beyond what was in the original mission plan," said mission director Dr Robert Farquhar. "We achieved the first landing of a spacecraft on an asteroid. When you talk about 'faster, cheaper, better', this is what 'better' means."

The final picture taken just before touchdown

It is now more than two weeks since Near-Shoemaker made a gentle landing on Eros. The probe ended up resting on the tips of its two solar panels.

Much to the amazement of the mission team, the touchdown was so gentle that the craft remained working and continued sending a signal back to Earth.

A 10-day extension of the mission was granted to allow Near's gamma-ray spectrometer to collect data from just above the surface.

Maximum sensitivity

"This is the first gamma-ray experiment that has ever been done on the surface of a body other than Earth," said Dr Jacob Trombka, of Nasa's Goddard Space Flight Center.

He added that it would take many months for researchers to scrutinise the data they had collected.

Engineers at Nasa's Deep Space Network (Dsn) terminated contact with the probe on Thursday. The Dsn consists of large antennae located in the US, Australia and Spain. The antenna at Goldstone, California, received the final download.

Near's position on Eros has prevented it from using its largest antenna to communicate with Earth. To receive the weaker signal from Near's low-gain antenna, the Dsn had been utilising its maximum sensitivity.