Apr 3, 2002 3 min read

CAPE CANAVERAL, Fla. (AP) – NASA confirmed the start of its launch countdown for space shuttle Atlantis on Tuesday, following new security guidelines intended to thwart a terrorist attack. The countdown clocks in the launch control center had actually started the previous evening for Atlantis’ liftoff Thursday afternoon on a space station assembly mission.

Under the 3-week-old policy, NASA won’t announce the start of the countdown until after the fact and won’t disclose the shuttle launch time until 24 hours in advance. In addition, the astronauts’ movements on launch day will not be televised live as usual.

Shuttle program manager Ron Dittemore said the policy has not hampered shuttle work or countdown activities.

“It does not change the team’s approach one bit,” he said.

NASA says liftoff will occur sometime between 2 p.m. and 6 p.m. Thursday. Forecasters put the odds of good launch weather at 70 percent, with low clouds and rain the main concerns.

The only shuttle concern involves the power-drive units needed to close the pair of trapdoors on Atlantis’ belly once the external fuel tank is jettisoned in space. A door on Endeavour closed several seconds slower than usual in recent ground testing, and engineers want to make sure the same problem does not happen to Atlantis.

Dittemore said he expects the engineering analysis to be completed by late Wednesday afternoon and that the findings should clear Atlantis for an on-time launch.

Atlantis is loaded with a 44-foot girder for the international space station that weighs nearly 27,000 pounds. It’s not just a basic metal beam: This $600 million truss has 475,000 parts, including a myriad of electrical cabling and plumbing and four sets of computers. It also has a $190 million railcar and track for eventual use by the space station’s robot arm.

Additional girders will be attached to this component on future flights, and the entire framework ultimately will stretch more than 350 feet with the railroad track running the full length. The track is needed to move the robot arm from one end of the space station to the other, to build up the orbiting outpost.

In a space shuttle first, Atlantis will be propelled by three new-style main engines during liftoff. The high-pressure fuel turbopump in each engine was built without welds, which was expected to make them more safe and reliable.

The seven astronauts assigned to Atlantis’ 11-day flight will be the first visitors for the three men who have been living on the space station since December. The shuttle crew is taking up fresh food and clean clothes for the space station residents.

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On the Net:

NASA: http://spaceflight.nasa.gov