Accusations that two Nasa astronauts were drunk in charge of space vehicles, and revelations of sabotage, have overshadowed the next mission which is due to lift off on 7 August. 

Officially Nasa maintains a 12-hour 'bottle-to-throttle' rule. But, according to a report in Aviation Week, on at least two occasions astronauts who broke the rule were still allowed to fly.

This was despite warnings from flight surgeons and fellow crew members that they were too drunk.

Exactly what they flew while drunk is not clear: it could have been a Shuttle, the Russian Soyuz space station or a 1000mph T38 training jet.

The drinking while flying scandal came to light after Nasa commissioned a " review of health services available to astronauts" and an assessment of astronauts' "behavioural medicine practices".

Although Nasa claimed that these procedures were routine, they are widely seen as a response to the arrest and dismissal of astronaut Lisa Nowak who drove from Texas to Florida dressed in a nappy to assault a love rival.

The sabotage was to a computer system which Nasa describes as "non-critical" destined for the next Shuttle flight. Inspectors found that wires on a telemetry device had been deliberately cut.

Nasa said that the unit will be repaired and used for the mission as planned.