The International Space Station this week suffered a major power shortage which has delayed a SpaceX supply run.
A shipment was due to be launched by SpaceX on Wednesday from Cape Canaveral, in Florida, but a power-switching unit malfunctioned at the station on Monday.
The fault knocked two power channels offline but the six remaining on the space station are working normally.
The station and its six astronauts are safe, Nasa said on Tuesday, but because of the hobbled solar-power grid, the SpaceX launch has been put back until at least Friday.
Nasa wants to replace the failed unit to restore full power, before sending up the Dragon cargo capsule.
There is no rush for this delivery as Northrop Grumman launched supplies two weeks ago.
Solar wings collect and generate electricity for the station.
Any breakdown in this system can cut into power.
