NASA probes mysterious oxygen leak during Discovery Launch

July 26, Discovery is launched at an inclination of 51.6 degrees and orbit altitude of 122 nautical miles. The launch is followed by an unexpected episode – a mysterious oxygen leak.

Now NASA is trying to reason why the leak would have taken place. One of the possibilities that it has come up with is highly flammable gaseous oxygen might have leaked into shuttle Discovery’s rear engine compartment during its first post-Columbia launch. Scouring over data from the test flight to the International Space Station, NASA engineers uncovered evidence indicating there might have been high concentrations of the hazardous gas in the compartment about two minutes after liftoff. NASA aims at resolving the issue before the shuttle mission as a leak could lead to a fire or even an explosion in the flight.

"We’re going to err on the side of caution," said Kyle Herring, a spokesman for NASA’s Johnson Space Center in Houston. "We’re going to run this thing to ground and make sure we understand it."

Fueled by 500,000 gallons of liquid hydrogen and liquid oxygen in the shuttle’s external tank, Discovery’s three main engines performed as expected and the ship reached its intended orbit with no apparent problems.

A serious leak likely would have left the shuttle short of its target, and an extra firing of its twin orbital maneuvering engines might have been required to make up for any shortfall. NASA also monitors the engine compartment during pre-launch fuel-loading operations and the final launch countdown to make certain there is no build-up of hazardous gasses.

Strict NASA rules call for a launch attempt to be scrubbed if gaseous oxygen concentrations in the compartment reach 500 parts per million, Kennedy Space Center spokeswoman Jessica Rye said. But there was no evidence of a build-up before Discovery and its seven astronauts were launched.

The data in question was retrieved from six so-called "catch bottles" that gather samples of air within the engine compartment during flight. Data from the devices cannot be retrieved until a shuttle returns to Earth.

Data from three of the devices showed that gaseous oxygen levels during flight were normal. Data from a fourth was corrupt.

Two of the catch bottles generated data that indicate higher-than-allowable levels of gaseous oxygen were present in the compartment about two minutes into flight.

The investigation into the apparent leak is not expected to have any immediate impact on preparations for NASA’s next shuttle mission, which the agency hopes to launch in May.

Routine prelaunch work will continue at KSC and other NASA installations. Engineers investigating the matter will report back to shuttle managers in January.