Tim Furniss/LONDON

The Mars Polar Lander Mission (MPL) was declared lost on 6 December after the failure of the seventh and final attempt to pick up signals from it using the orbiting Mars Global Surveyor.

NASA administrator Dan Goldin says that a detailed review will be conducted of the agency's future Mars exploration plans. The proposed programme of launches to Mars every two years through to 2013 may be slowed following the failure of the MPL and the Mars Climate Orbiter (MCO) in September.

The next mission of an orbiter and lander scheduled for launches in 2001 could now undergo major changes. Ed Weiler, deputy director of NASA's Office of Space Science, says: "I am not convinced that we will go forward with 2001-I have no confidence that it will be successful."

The 2001 Mars craft are based on the MCO and MPL. The lander would deploy a mini-rover similar to the Sojourner which successfully roamed the surface of Mars in the Mars Pathfinder mission of July 1997.

The Mars 2005 mission was scheduled to return samples from Mars to the Earth as a part of a joint programme with France.

Goldin admits that "clearly something is wrong and we have to understand that-it is conceivable that we will completely change our approach". Lockheed Martin, which built the MCO and MPL, will also come under scrutiny.

Goldin's "faster, better, cheaper" approach to spacecraft is coming under severe criticism after the dual loss of the MCO and MPL. The two spacecraft cost about $350 million, compared with the $1 billion cost of landing two Viking probes on Mars in 1976.

Goldin adds, however, that there is "no way" NASA will go back to a policy of producing multi-billion-dollar spacecraft such as the Mars Observer, which was lost in 1993.

Although NASA has a good early record of Mars exploration, it has lost three spacecraft, placed one in orbit and made one safe landing since 1993.

Since 1964 it has recorded five failures and eight successes. By comparison, the former Soviet Union and Russia has an even worse record in Mars exploration, with almost every craft launched since 1960 failing.

After the failure of the MPL, the orbiting Mars Global Surveyor (MGS) may be called into action to take 1.5m high-resolution images of the MPL's landing target area close to the planet's south pole, in the hope of spotting evidence of the craft's landing or debris.

Signals from the two autonomous Deep Space 2 microprobes, which were to have separated from the MPL before its landing, have not been heard either, so it is likely that the whole craft may have burned up in the Martian atmosphere or suffered some other catastrophe.

Source: Flight International