It is called the Red Planet for its appearance from orbit, but Mars may well be a rainbow of colours.

NASA has revealed impact craters which expose subsurface materials on steep slopes.

These slopes often experience rockfalls and debris avalanches that keep the surface clean of dust - revealing a variety of hues.

An enhanced-colour image from NASA's Mars Reconnaissance Orbiter shows several different rock types.

Image: NASA/JPL/University of Arizona

The bright reddish material at the top of the crater rim is from a coating of the Martian dust.

The long streamers of material are from downslope movements.

While also revealed in this slope are a variety of bedrock textures - with a mix of layered and jumbled deposits.

"This sample is typical of the Martian highlands, with lava flows and water-lain materials depositing layers, then broken up and jumbled by many impact events", NASA says.

This image was taken by the High Resolution Imaging Science Experiment (HiRISE) camera on February 28th, 2011 at 3.24pm local Mars time.

But it has only recently been released.