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Contact: Erica Rolfe
European Space Agency

Radar to reveal hidden Mars

MARSIS prospecting for water
Click here for a high resolution photograph.

A new chapter in the exploration of Mars is about to begin. After a long delay, the MARSIS radar instrument on board ESA’s Mars Express orbiter is about to swing into action.

MARSIS is the first instrument designed to look below the orange-red surface of Mars. It works by beaming down low frequency radio signals. Many of these bounce straight back from the surface. But some signals go through the ground and rebound from subsurface layers.

By analysing these echoes, scientists hope to discover underground ice or water. This is important, because life is usually linked to the presence of water.

MARSIS main antenna
Click here for a high resolution photograph.

MARSIS will also detect rock layers to a depth of several kilometres and measure the height of mountains and valleys.

Before this can happen, the radar’s three rod-like booms must be unfolded. These should have been released in April 2004, but there was some concern that they could get stuck or bounce back and damage the spacecraft. “Such deployments cannot be demonstrated on Earth,” explained ESA’s John Reddy. “That’s why, unless they can be tested in space, we have to rely on computer simulations.”

After careful analysis of the risks, ESA has decided to go ahead with the experiment. The two 20-m-long booms will be deployed first, followed by the 7-m boom a few days later. This is expected to take place between 2 and 12 May.

Once the deployment is complete, MARSIS will undergo three weeks of testing. Then the exciting radar search will begin.