The agency knows the Red Planet exerts a powerful hold over the public

"The emphasis has shifted back to mission success as opposed to funding," said Firouz Naderi, manager of the Mars Programme Office at the Jet Propulsion Laboratory (JPL).

This is why Nasa has returned to its last successful Mars mission, Pathfinder.

It has decided to concentrate on a bigger version of Pathfinder - its landing mechanism may have been unorthodox, it bounced across the surface in a giant inflatable sphere, but at least it worked. Even better, it was relatively cheap.

But redirecting its efforts into what it hopes is a dead certainty for success means cancelling a number of other Mars missions.

Tough competition

Out go ambitious plans for a series of missions culminating in a sample of Mars rock being brought back to Earth by 2008.

A series of missions is a series of potential disasters for which Nasa no longer has the stomach or the finances.

An artist's impression of the lost Mars Polar Lander

The agency knows the Red Planet exerts a powerful hold over the public, which translates into good PR for them, and that means Mars missions remain popular as well as scientifically important.

With the discovery of evidence for recent flowing water on the Red Planet, Nasa is itching to get back in business.

And yet, it could well be beaten by the European Space Agency. Esa's Mars Express mission will launch on 1 June, 2003, (the first day of an 11-day launch window), and the UK-led Beagle lander will touch down on the Martian surface on 26 December - if all goes to plan.

Luck still plays a large part in space exploration.

Nasa may well pull itself out of its current gloomy patch but a worst case scenario sees the Europeans beating them back to Mars, and their own mission, announced on Friday, proving to be another costly failure.