This is actually a few weeks old, but better late than never. Flight controllers for the Mars Express spacecraft decided to delay deployment of the subsurface radar antenna boom. They fear that the boom might swing too far and richochet back into the spacecraft, possibly damaging it and crippling the mission. A final decision on the radar’s deployment will be made later this year.
The radar is designed to search up to 5 kilometers beneath the Martian surface, looking for traces of water buried beneath the rocks.