The suspected crash site for Nasa's Mars Polar Lander spacecraft - lost in 1999 - has turned out to be nothing more than a natural feature.
Last year, scientists made a tentative identification of the missing probe in images from the Mars Global Surveyor (MGS) spacecraft in orbit around Mars.
The pictures showed a dark area with a central spot thought to be the lander and what looked like its parachute.
But a recent flyby of the area shows this interpretation was incorrect.
The images analysed from MGS earlier this year were not conclusive because, at 1.5m per pixel, the camera's resolution was not high enough.
But Mars Global Surveyor made another pass of the presumed crash site on 27 September this year and used a manoeuvring technique called cProto, in which the spacecraft is pitched to slow the apparent speed of the ground below.
This allows its camera to focus on a particular target for longer, resulting in a better resolution image.
Now you see it
In the images from this latest pass, the dark feature that was identified as possible rocket blast zone had faded. This would be expected owing to dust deposited by storms.
But more importantly, the spot interpreted to be the lander has disappeared.
Researchers from Malin Space Science Systems in San Diego, California, which operates the camera, said the bright spot which appeared in the original pictures was probably due to noise.
The feature identified as a candidate for Mars Polar Lander's parachute in fact turned out to be the illuminated slope of a small hill, one of several in the area.
"This is NOT the location of the Mars Polar Lander," the researchers wrote on their website.
Mars Polar Lander (MPL) failed to establish radio contact with Earth as it was supposed to after a self-controlled touchdown near the edge of Mars' southern polar cap on 3 January 1999.
Its disappearance 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.