US defends Mars images

NASA 'sexed up' images of Mars sent back by its two rover vehicles to make the planet look red, it has been claimed. Space experts say the ordinary looking brown scenery was digitally altered to make it redder.

Some conspiracy theorists even claim Nasa doctored the colours to hide evidence of life, such as green patches, New Scientist magazine reported.

Nasa admitted the infrared filters used on the rovers' cameras made the planet look more red.

But it said that was only done to help geologists distinguish different rock types. Exactly how red the Martian surface appeared depended greatly on its sky, a spokesman added.