Nasa is investigating the apparent sabotage of a computer due to be flown to the International Space Station.
The US space agency said the damage to wiring in a network box was intentional and obvious, but said it could be repaired before take-off on 7 August.
Nasa stressed that the lives of its astronauts had not been put at risk.
The discovery came as an independent health panel was reported to have found that astronauts had been allowed to fly after drinking alcohol.
The panel found that on two occasions Nasa astronauts had been allowed to fly despite warnings from flight surgeons and other astronauts that they were so drunk they posed a safety risk, flight journal Aviation Week and Space Technology reported.
The panel was set up by Nasa to study health issues following the arrest on kidnapping and assault charges of the astronaut Lisa Nowak.
Ms Nowak is accused of attacking her love rival, the girlfriend of a fellow astronaut.
The findings of the panel do not deal with Ms Nowak directly or mention any other astronaut by name.
The official review into astronauts' medical and behavioural health is expected to be released by Nasa on Friday.
The agency has so far refused to comment on the allegations.
Nasa's Associate Administrator for Space Operations, William Gerstenmaier, said the apparent sabotage of a non-essential computer had been discovered earlier this month.
"The damage is very obvious, easy to detect," he told reporters. "It's not a mystery to us."
Mr Gerstenmaier said wires had been found cut inside the unit before it had been loaded onto the shuttle.
The computer is designed to collect and relay data from sensors which detect vibrations and forces on the space station's external trusses.
"It's currently being investigated by the [Nasa] inspector general's office," he added.
The equipment had been supplied by a sub-contractor, he added.
Mr Gerstenmaier said engineers would try to repair the hardware before take-off in two weeks' time, but that the mission would not be delayed.
The damage is believed to be the first act of sabotage of flight equipment Nasa has discovered.