NASA is using one space probe orbiting Mars to search for another spacecraft left missing around the planet.

Earlier in the month, the Mars Global Surveyor lost contact with Earth for two days, and last week NASA received a weak signal without data. The probe since has not confirmed receiving a command to direct one of its transmitters to Earth.

On Nov. 17, NASA directed another probe, the Mars Reconnaissance Orbiter, to point its cameras toward where the Surveyor might be, but scientists were reportedly uncertain whether it would be found.

Launched on Nov. 7, 1996, to systematically map Mars, the Surveyor is the longest-operating Martian exploration craft.