- - Thursday, April 14, 2005

NASA has filled a 154-foot-high external tank with fuel and oxygen for the first time since the Space Shuttle Columbia accident.

The fueling wasn’t for launch, but for a test yesterday to assure engineers that all of the changes to the tank worked as expected.

The test also gave the launch team a dress rehearsal for Space Shuttle Discovery.

“We’ve hit some major milestones in the last couple of weeks,” said launch director Mike Leinbach. “Today’s test was a major milestone. The next one is launch, and I’m really looking forward to that one.”

Several significant changes have been made to the external tank in the aftermath of the Columbia accident. The most notable change is the removal of the wedge-shaped insulating foam.

A 1.67-pound piece of foam fell off that area during Columbia’s launch. The piece slammed into Columbia’s wing and damaged the heat-protection system, dooming the shuttle on re-entry on Feb. 1, 2003.

A NASA engineer explained that yesterday’s test was conducted to make sure that there was “nothing unexpected or unexplained happening” when supercooled liquid oxygen and hydrogen fuels were added to the tank.

Such tanking tests were performed before each of the first several shuttle launches, but officials later determined they weren’t needed under normal circumstances.

NASA tested the “super-lightweight” tank when it was first used in 1998 and conducted a few “mini-tanking tests” in 1990 on Atlantis and Columbia. Mysterious leaks were detected in Columbia’s plumbing, but only at the super-cold temperatures when the tank was loaded with liquid hydrogen.

The window for Discovery’s launch is May 15 to June 3 to achieve proper orbital mechanics and optimal lighting conditions. If the shuttle doesn’t launch by June 3, the next opportunity will be in July.

NASA is also preparing Space Shuttle Atlantis to serve as a rescue vehicle in case a fatal problem is found on Discovery. If the Discovery crew cannot return to Earth safely, they will live on the International Space Station for up to a month while Atlantis undergoes its final launch preparations.

Shuttle manager Wayne Hale said engineers have several concerns about debris from the tank that could harm the shuttle. “Ice is a biggie,” he said, adding that the crew will continue to conduct tests as the launch approaches.