MARSIS is ready to go digging on Mars

The Mars Express MARSIS experiment is at last fully deployed, seven weeks after the European Space Agency gave the go ahead for the radar booms to be unfurled. ESA announced yesterday that the Mars Advanced Radar for Subsurface and Ionosphere Sounding experiment has undergone its first checkout, and is ready to start scanning the red planet.

The MARSIS experiment is the last science package on board the Mars Express Orbiter, and will provide scientists with their first glimpse of what is going on beneath the surface of Mars. It consists of three antennae: two dipole booms, each 20 metres long, and one seven-metre mono pole boom, arranged at 90 degrees to the first two.

Unfurling the booms was a delicate and uncertain process. A hinge on the first boom got stuck while it was being unfolded back in early May, and after some deliberation mission controllers managed to get it to lock properly by turning the stuck portion to face the sun. The heat from Sol was enough to expand the section so that it locked into place.

The second boom was successfully extended by mid June, and the third deployment on 17 June went very smoothly, ESA said.

Professor David Southwood, ESA's science programme director, acknowledged the importance of the international collaboration between the European space agencies and NASA in making the Mars Express mission a success. "Overcoming all the technical challenges to operate an instrument like MARSIS, which had never flown in space before this mission, has been made possible thanks to magnificent cooperation between experts on both sides of the Atlantic," he said.

MARSIS will send out a coded stream of radio waves towards Mars at night, and scientists will analyse the echoes to make deductions about the surface and subsurface structure, as well as the structure of the upper atmosphere. In particular, they will search for water that might lie hidden below the surface. ®

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