The space shuttle Endeavour lifts off in twilight, bound for the International Space Station. Photo: Steven Young/Spaceflight Now

Under fighter jet protection, the heavily guarded space shuttle Endeavour finally rocketed into orbit this evening, carrying a fresh crew for the international space station and thousands of flags to honor the victims of the Sept. 11 terrorist attacks.

"Have a great flight and to the Expedition 4 crew, farewell," launch director Michael Leinnbach radioed minutes before liftoff.

"We'd like to say thank you to the entire KSC team for getting Endeavour in great shape," commander Dominic Gorie replied. "Secondly, from the entire crew, we're all well aware that for over 200 years, and certainly over the past two months, freedom rings loud and clear across this country. But right here, right now, it's time to let freedom roar. Let's light 'em up!"

And so, after delays caused by problems in space last week and bad weather Tuesday, Endeavour leaped away from pad 39B at 5:19:28 p.m., the moment Earth's rotation carried the launch pad into the plane of the space station's orbit.

Joining Gorie aboard Endeavour are pilot Mark Kelly, flight engineer Daniel Tani, Linda Godwin and the station's fourth full-time crew, Expedition 4 commander Yury Onufrienko, Daniel Bursch and Carl Walz.

If all goes well, Gorie will guide Endeavour to a docking with the 15-ton space station around 3:04 p.m. Friday.

The primary goal of the mission is to deliver Onufrienko and company and to bring the lab's current occupants - Expedition 3 commander Culbertson, Vladimir Dezhurov and Mikhail Tyurin back to Earth after 126 days in orbit. The Expedition 4 crew will remain on board until next May.

Endeavour also is carrying several tons of equipment and supplies, including fresh food, clothing and a five-octave electronic piano. Walz, an accompaniest at his Houston-area church, promises occasional concerts from space during his stay in orbit.

In a symbolic gesture, 6,000 small four-inch by six-inch American flags were packed away aboard Endeavour that will be given to family members and survivors of the men and women killed during the Sept. 11 terrorist attacks in New York and Washington.

A large American flag found in the rubble of the World Trade Center also is packed away on the shuttle, along with a Marine Corps flag found in the Pentagon and a U.S. flag from the Pennsylvania state capitol that was flying when one commandeered aircraft crashed.

Finally, the crew is carrying 23 New York Police Department shields, 91 police department patches and a poster with pictures of the New York fire fighters who perished in the World Trade Center collapse.

"A lot of us probably wonder how do you do something to contribute, to helping us get out of this feeling you have afer the tragedy and help the people out who were so personally hit by it," Godwin said before launch. "This is maybe a very small way of doing that."

Not surprisingly, Endeavour's countdown was carried out under unprecedented security, with fighter jets patrolling the launch area and small planes barred from approaching within 35 statute miles of pad 39B.

A powerful mobile radar system capable of detecting objects nine feet across within a radius of 230 miles was in operation at the nearby Cape Canaveral Air Force Station.

Many shuttle flights are held up by boats that stray into an off-shore danger zone, but there were no such reports today. The Coast Guard enforced a strict three-mile off-shore buffer zone, along with a standard downrange corridor where debris would fall in the event of a launch mishap.

Crowds at the Kennedy Space Center were down sharply as NASA barred area residents and tourist from driving on site to view the launching from a nearby causeway for the first time since shuttles began flying in 1981.

Again, there were no reported incidents other than the interception of a wayward helicopter Tuesday.

Endeavour originally was scheduled for launch last Thursday, but the flight was put on hold after a Russian Progress supply ship ran into problems linking up with the space station the day before. While the unmanned vehicle successfully "soft docked," Russian flight controllers were unable to lock it firmly in place.

NASA managers, concerned a shuttle docking could cause the loosely docked Progress to rock back and forth enough to cause structural damage, ultimately decided to delay Endeavour's launch until after a spacewalk by Dezhurov and Tyurin to fix the Progress problem.

On Monday, the cosmonauts did just that, removing a long piece of a rubber O-ring seal from the docking interface that was preventing the Progress from snugging up for an airtight seal. The supply ship then was "hard docked" without incident, clearing the way for Endeavour's launching Tuesday.

But this time around, the weather refused to cooperate. While forecasters held out hope conditions would improve enough to permit a liftoff, low clouds persisted and showers began near the launch pad as the opening of Endeavour's launch window approached.

Finally, with the countdown holding at T-minus five minutes and with less than one minute remaining to pick up the count, mission managers ordered a 24-hour delay.