NASA announced Nov. 21 that its Mars Global Surveyor has likely finished operations after a 10-year mission, the longest one sent to the red planet.

The spacecraft has not communicated with Earth since Nov. 2, days short of the anniversary of its Nov. 7, 1996, launch. Its camera had returned more than 240,000 images to Earth.

NASA reported preliminary indications were that a solar panel became difficult to pivot, possibly preventing the spacecraft’s ability to generate sufficient power to communicate. Engineers are still exploring other possibilities for the radio silence.