The European Space Agency has given the go-ahead for the deployment of the MARSIS radar, built by Alenia Spazio (a Finmeccanica company), on board the Mars Express interplanetary probe in the first week of May, 2005. MARSIS (Mars Advanced Radar for Subsurface and Ionospheric Sounding) will search for water and ice distribution in the upper layers of the Martian crust using techniques similar to terrestrial oil prospecting to analyse radiowave echoes in the first 5 km of the subsurface, revealing the structure and distinguishing a dry area from a wet or icy one.

Built for the Italian Space Agency by Alenia Spazio in collaboration with NASA’s Jet Propulsion Laboratory and La Sapienza University of Rome, MARSIS consists of three antennas, two supported on 20-metre booms and one on a 7-metre boom. The three booms were initially to have been deployed in April 2004, but computer simulations revealed the possibility of a whiplash effect during deployment that could have damaged the Mars Express spacecraft. In January, the ESA review board concluded that although the risk of impact could not be rule out, the probability of serious damage was very small and recommended planning the deployment for the week beginning 2 May. However, it might be possible to start deployment during the week of 25 April which would be better from a scientific point of view as the Mars Express orbit will allow radar measurements of the most interesting scientific regions on Mars to start in May 2005.

MARSIS will probe Mars’s subsurface at least until 30 November 2005, the nominal end date of Mars Express operations, and beyond if the mission is further extended.

Mars Express was launched on 2 June 2003 and reached the planet on 25 December 2003. Since entering its operational orbit on 28 January 2004, it has been performing studies and global mapping of the atmosphere and surface, analysing their chemical composition, and delivering images of the Martian landscape.

Besides its involvement in the MARSIS radar, Alenia Spazio was main contractor to ESA for the assembly, integration and testing of the Mars Express spacecraft and provided the related ground support equipment. The company also constructed the two satellite S/X-band transponders for the link between Mars Express and Earth.