Life support systems on the International Space Station could be compromised following the failure of the computers that support them.
The computers also control navigation systems, exacerbating the problem.
In a worst case scenario, crew of the 16-nation space station could be forced to leave.
Computers failed in the Russian section of the space station and, without them, the station may be unable to maintain proper orbit or allow crew to remain on board.
All three lines of the Russian computers are affected, to the extent that they are unable to reboot themselves, according to NASA officials.
Engineers are working on solving the problem, including looking at whether a new solar power unit could be the cause.