The space shuttle Endeavour. Photo: NASA

Endeavour's launching, like all flights to the space station, is timed to coincide with the moment Earth's rotation carries the launch pad into the plane of the station's orbit. That plane is tilted 51.6 degrees to Earth's equator.

The shuttle has enough power to launch five minutes to either side of the moment the pad is "in plane" with the station. For technical reasons, NASA only uses five minutes of that 10-minute launch window, taking off when the pad is essentially directly in the plane of the station's orbit.

"You launch into an orbit that is lined up with the space station exactly," Cockrell said in a NASA interview. "If you don't, the mission is blown. Once you get into orbit you cannot change the orbit from side to side."

Altitude, however, is another matter and the lower the altitude, the higher the spacecraft's velocity. Endeavour will launch into the station's plane but orbit at an initially much lower altitude.

"Generally speaking, we'll be several thousand miles behind the space station," Cockrell said. "It really doesn't matter where it is on its orbit so long as we're under the track that it's on. We will stay down at a lower altitude, about 120 miles. The fact that we're at a lower altitude makes us go around the Earth faster.

"So, in a matter of a day-and-a-half, we will catch up with the space station," he said. "And, as we start to catch up, we'll gradually raise our altitude up closer to the space station's altitude so that our catch-up rate slows down. It becomes more gradual."

The space shuttle sails over South Florida as seen in this file image from Endeavour's last flight. Photo: NASA

The terminal rendezvous phase will begin two days after launch with the shuttle trailing the station by about 9.2 statute miles. From there, Cockrell and Lockhart will oversee a series of computer-controlled rocket firings designed to place the shuttle at a point 600 feet or so directly below the space station.

At about that point, Cockrell will take over manual control and pilot Endeavour in a slow loop up to a point 300 to 400 feet directly in front of the lab complex as both spacecraft race through space at five miles per second.

"We're going to come underneath it," Cockrell said. "We just tell the autopilot to start tilting the tail towards the Earth and then we scoot it along so that, as it tilts toward the Earth, we end up in front of the space station. It's kind of quasi-magic, but it works.

"And then, while we're up here in front of the space station, the computer or the autopilot just holds the tail pointed straight at the Earth, and then we just guide it left, right, and in and out, down towards the station."

The station will be oriented with its long axis in the direction of travel. A pressurized mating adapter mounted on the forward end of the Destiny laboratory module will face Endeavour. Destiny, in turn, is attached to the U.S. Unity module, a multi-hatch gateway linking the lab to the rest of the station.

Directly across Unity from Destiny is a pressurized mating adapter leading into the Russian Zarya propulsion and cargo module. Zarya, in turn, is attached to the Russian Zvezda command module at the aft end of the station's long axis.

A Progress supply ship currently is docked to Zvezda's aft port while the on-board crew's Soyuz lifeboat is docked to a downward-facing port on the Russian-built, NASA-financed Zarya module. Another Russian docking port in a module attached to Zvezda is currently vacant.

Extending 90 feet up from the Unity module's zenith hatch is the Z1 truss and P6 solar array, which provides the bulk of the station's current power. The P6 array ultimately will be repositioned at the end of the station's main truss, the first element of which was installed during the most recent station assembly mission in April.

The station's Quest airlock module, which will be used for all three of the upcoming STS-111 spacewalks, is attached to Unity's right-side, or starboard, hatch.

Animation shows Endeavour on final approach to docking. Photo: NASA TV/Spaceflight Now

Positioned directly in front of the station's long axis, Cockrell will manually guide Endeavour in so the docking system in the shuttle's cargo bay can mate with its counterpart on the pressurized mating adapter, or PMA. After hooks and latches engage, the two spacecraft will be locked together.

"It's really a fun piloting task," Cockrell said. "It's like driving a ship. You make very small inputs that take a long time to occur; but once they occur, they're very hard to stop. So it's something you need to do very precisely and it takes a lot of practice.

"So we go in very slowly and gradually, we slow down at about 30 feet away from the docking port and just look through a zoomed-in camera at the target. The target has a little set of alignment guides on it and we make sure that we're all lined up, that the two vehicles are exactly in plane.

"And then, from 30 feet in, we just hold a steady rate and we crash into the station," he joked. "That's a very slow crash. It's one-tenth of a foot per second. It's as slow as a snail would crawl."

After leak checks, hatches between the two spacecraft will be opened and station commander Yuri Onufrienko and his two Expedition 4 crewmates, Daniel Bursch and Carl Walz, will welcome the shuttle/Expedition 5 crews on board. After a safety briefing, the combined crews will get down to work.

But along the way, the shuttle astronauts plan to keep the station crews entertained.

"We have planned a few special things," Cockrell said. "The shuttle food menu has really grown in its size and variety in the past few years. I think it's been driven to give the expedition crews a bigger variety. So we found a way to have a Mexican day, an Asian day, a surf-and-turf day and a cajun day within the boundaries of the shuttle food menu.

"It's always good to come together as a crew of 10 and have a meal together. It really serves to recharge the batteries."

Given the combined crew's busy flight plan, they'll need it.

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