A backup computer outside the International Space Station is on the fritz.

CBS News Space Consultant Bill Harwood says the computer helps control the station's robotic arm:

'If the flight controllers at the Johnson Space Center in Houston can't figure out a way to get this computer system back in operation, their only other option would be to simply replace it. Now, they have spares on board, but it would require a space walk to go outside and actually swipe these boxes out.' 

A commercial spacecraft is set to launch next week, and the station's robotic arm is needed to help pull it aboard.