Controllers with the European Space Agency have deployed the first of Mars Express' MARSIS radar booms. During the operation, however, they detected an anomaly with one of the 13 segments that make up the telescoping boom - segment 10 hasn't fully locked into place. Controllers are going to hold off extending the second boom until they can figure out what's happening with the first. Once fully deployed, the MARSIS radar will allow Mars Express to map the subsurface of the Red Planet, searching for underground reservoirs of water.