MARSIS fully deployed

This is an impression of the completely deployed MARSIS experiment on board ESA's Mars Express orbiter. Its two 20-metre booms and the 7-metre booms are sprung out and locked into place.

The MARSIS experiment will map the Martian sub-surface structure to a depth of a few kilometres. The instrument's 40-metre long antenna booms will send low frequency radio waves towards the planet, which will be reflected from any surface they encounter.