Mars rover Spirit falls silent

Bogged down in soft ground in Gusev Crater, NASA's Mars rover Spirit never woke up after undergoing its coldest Martian winter. Now NASA has announced that efforts to contact the rover have come to an end.

Mission scientist Steve Ruff of Arizona State University's Mars Space Flight Facility called Spirit's time on Mars "a Cinderella story" for overcoming early struggles.

Ruff is the scientist in charge of day to day operations for the Miniature Thermal Emission Spectrometer (Mini-TES) instrument, designed by ASU professor Philip Christensen of the School of Earth and Space Exploration. A duplicate Mini-TES is on Spirit's twin rover, Opportunity, which is still exploring Meridiani Planum on the other side of Mars from Spirit.

As hard as it is to accept Spirit's fate, Ruff said he was comforted that there was time to say goodbye.

"It wasn't like an overnight death. It was a slow decline," he said. "It gave me some time to adjust to the reality that the mission was probably over or about to be, so it wasn't as painful."