An imaging scientist thinks he may have found Nasa's Mars Polar Lander (MPL).

The US space agency probe went missing as it attempted to touch down at the Red Planet's south pole in 1999.

Michael Malin's team has re-examined pictures taken by the orbiting Mars Global Surveyor spacecraft, which searched for the lander in 1999-2000.

He reports the assessment of the images in the July issue of Sky and Telescope magazine, and says they could help confirm why the mission failed.

"The observation of a single, small dot at the centre of the disturbed location suggests that the vehicle remained more or less intact after its fall," he writes.

Michael Malin is president and chief scientist of Malin Space Science Systems, which operates the camera aboard Global Surveyor.

The image processing and interpretation skills of his company have already produced remarkable pictures of the landing locations of the current US rovers, Spirit and Opportunity.

Indeed, it was that success which prompted Dr Malin's team to go back to the MPL search shots.

Tell-tale signs

The official investigation into the loss of the Mars Polar Lander concluded that a software error shut down the probe's landing rockets too early.

It is thought that as the $165m robot approached the ground, its onboard systems confused the jolt from the deployment of a landing leg with ground contact.

When the rockets then cut out, the MPL would have crashed down from a height of about 40m (130ft).

Dr Malin thinks he can identify a parachute close to the imaged location, and he says disturbed ground matches what one would see if a rocket had blasted the surface from a height of tens of metres.

"It seems that the MPL investigation board may have been correct," Dr Malin tells Sky and Telescope.

"MPL's descent proceeded more or less successfully through atmospheric entry and parachute jettison. It was only a few short moments before touchdown that disaster struck."

Viking, too

Mars Global Surveyor will go back to the "candidate" and re-image it using a technique that should achieve a resolution of 0.5m per pixel.

MPL's disappearance in 1999 was the second of two quick blows to Nasa's Mars programme. The lander's sibling spacecraft, the Mars Climate Orbiter, was lost three months earlier.

The board that examined its loss concluded the cause lay in a mix-up over units, with one team on the mission using metric measurements and another using English units (US equivalent of UK imperial).

Dr Malin's team also report finding the Viking Lander 2, which touched down on Mars' Utopia Planitia in September 1976 (just a month and a half after its twin, Viking Lander 1).

This image shows the distinctive outline of the probe, which consisted of a wide six-sided platform sitting on three extended legs.

The July 2005 issue of Sky and Telescope goes on sale worldwide from 31 May.