Mars Express stares at volcano

Mars Express stares down at the Olympus Mons caldera

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Europe's Mars Express space probe in orbit around the Red Planet has produced a stunning image of the highest volcano in the Solar System.

The probe produced images of Olympus Mons, a 22 kilometre-high volcano.

The images show the volcano's caldera, the circular depression from which magma erupts or is withdrawn.

"I was amazed myself at how good it is," Professor Gerhard Neukum, principal investigator on the probe's camera told BBC News Online.

Olympus Mons is almost three times the height of Mount Everest in the Himalayas. The Martian volcano's caldera alone has a depth of three km.

This image combines data from different science instruments

The top-down colour image was taken from a height of 273 km above the surface using the orbiter's High-Resolution Stereo Camera (HRSC). It covers a distance of about 102 km across with a resolution of 12 m per pixel.

Caldera collapse

The main caldera collapse was caused when lava production ceased. This emptied the magma chamber and caused the caldera to collapse in on it.

Later lava events produced new collapses, seen as the smaller circular depressions in the picture, that have destroyed the round shape of the original one.

By combining different channels on the camera, the image can be viewed from different angles

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The pictures reveal a tongue-shaped landslide inside the caldera's steep southern wall. Striations that can be seen in the crater are tectonic faults.

Scientists have also produced a black-and-white image of the volcano in its entirety by superimposing topographic data from the probe's Mars Orbiter Laser Altimeter (Mola) instrument with a wide-angle mosaic image from the Mars Orbiter Camera (MOC).

A perspective view of the southern part of Olympus Mons' caldera was generated by combining different channels on the HRSC.