The national space agency in India says contact has been lost with the country's only satellite, which is orbiting the moon.
Communication links with the Chandrayaan-1 were cut abruptly early on Saturday, the BBC reports, and it is not clear what might have happened.
The satellite was launched amid fanfare in October last year in what was billed as a two-year mission of exploration.
It was intended as a first step towards landing an unmanned rover vehicle on the moon.
Earlier this year a sensor on the satellite was burnt by solar radiation.
A statement says scientists are reviewing data as they investigate the loss of contact.