Endeavour awaits liftoff. Photo: NASA

With NASA on a semi-wartime footing, engineers are readying the space shuttle Endeavour for blastoff Thursday on a space station crew rotation mission marked by haunting symbolism and unprecedented security.

"We are the first to launch since Sept. 11," said pilot Mark Kelly. "A space shuttle launch is always a real significant event and especially now, being the first ones up since then, I think it will be something that will bring a lot of pride to the people.

"The United States stands alone with just one other nation that can launch humans into space. And that's something that every American should be really proud about."

NASA and the Air Force have implemented extraordinary - but largely undisclosed - security precautions for the first shuttle flight since the war on terrorism began, barring members of the public from driving into the Kennedy Space Center on launch day for the first time since shuttles began flying in 1981.

Those who are allowed on the base, from VIPs and journalists to NASA employees and contractors, will be subjected to close scrutiny, hands-on ID checks and random car searches. SWAT teams will be evident. A limited number of tourists and area residents willing to buy tickets will be able to enter the space center on buses.

In another first for the shuttle program, reporters, photographers and even off-duty spaceport personnel will not be allowed to witness the astronauts' departure from crew quarters to the launch pad, a traditional launch day "photo op."

More important, of course, is what is being done to protect Endeavour, one of four irreplaceable $2 billion spacecraft that are world-wide symbols of America's technological prowess.

Loaded with a half million gallons of highly explosive rocket fuel, a shuttle on the launch pad represents an enormously visible - and intrinsically vulnerable - target for any would-be terrorist with even a light aircraft who might try to crash into the ship's thin-skinned external fuel tank.

NASA will not discuss what is being done to protect Endeavour. But F-15 fighter jets patrolled the sky when the shuttle was hauled out to the launch pad and it is widely assumed fighter protection will be on station during Endeavour's countdown.

There may even be anti-aircraft batteries stationed around the pad or other weapons capable of shooting down a suicidal terrorist aircraft. Reporters have not been allowed to visit the launch complex since the Sept. 11 attacks.

But the Air Force allowed photographs of similar gun emplacements set up at nearby Patrick Air Force Base and it's widely assumed weapons systems of some sort are in place at the spaceport.

Whatever the details, Endeavour's astronauts say they are satisfied they will be safe when they strap in for launch on the 107th shuttle mission.

"One of my first thoughts, even on the day of the 11th when we were in the middle of some training exercise, was gosh, you know, a shuttle on a launch pad, that's a target," said spacewalker Linda Godwin. "And we all thought about that."

Since then, "we have come to know most of the security measures that are in place and I don't see how they could be doing anything else," she said. "I don't think the answer is not to launch shuttles. That's allowing the enemy another victory.

"I think we have to do this and I do think all the security is in place," she said. "As (commander Dominic Gorie) has said, for that period of time, we may be some of the best protected people in the country."

Said Gorie: "We are totally confident. I'm not able to talk about any specifics, but we are very, very pleased with all that's been done for security here."

Godwin, Gorie, Kelly, Daniel Tani and Expedition Four space station astronauts Yuri Onufrienko, Daniel Bursch and Carl Walz, are scheduled for liftoff from pad 39B at 7:41 p.m. EST Thursday. It will be the 27th night launch in shuttle history.

The goal of the year's sixth and final shuttle flight is to deliver the Expedition Four crew to the international space station and to bring the lab's current occupants - Expedition Three commander Frank Culbertson, Vladimir Dezhurov and Mikhail Tyurin - back to Earth after 120 days in orbit.

Endeavour also will deliver more than three tons of scientific equipment, fresh food and other crew supplies, along with a half-ton of fresh water. Another 4,400 pounds of experiment samples, trash and no-longer-needed equipment will be brought back to Earth when the shuttle returns on Dec. 10.

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