The five Atlantis astronauts speak to reporters at pad 39A's slide-wire basket area. Photo: NASA

The Atlantis astronauts reviewed emergency procedures at pad 39A today, fielded questions from reporters and geared up to strap in Saturday for the final hours of a dress-rehearsal countdown.

"When we come down to the Cape and actually climb in the vehicle, it sort of marks a turning point," said commander Kenneth Cockrell. "It's exciting to us, it's when the realization finally comes that this really is going to happen."

Cockrell, pilot Mark Polansky, flight engineer Marsha Ivins and spacewalkers Thomas Jones and Robert Curbeam are scheduled to blast off on the 102nd shuttle mission Jan. 19 at 2:11 a.m. EST (0711 GMT).

The goal of the flight is to deliver and attach the $1.38 billion U.S. laboratory module, Destiny, to the international space station, clearing the way for the start of science operations later this spring.

Looking fit and relaxed at an emergency bunker near the base of the launch pad today, the astronauts said they were looking forward to a particularly challenging flight, one that will require three spacewalks and days of work inside to outfit and activate the new lab module.

"We believe this is a very important mission because it's a turning point in what we're doing with the international space station," Cockrell said.

Atlantis sits atop the launch pad following rollout earlier this week. Photo: NASA

"Once the lab gets to space station, control of station shifts from Moscow to Houston and the folks in Houston and at NASA are very excited about that and so it's become a big-deal, high-pressure flight, and we've been working really hard to get ourselves ready for it.

"We think we've got a mission that's full of all kinds of excitement and full of all kinds of work for us to do and plenty of work for people on the ground," he said.

The 32,000-pound Destiny module will be attached to the space station's multi-hatch Unity module. First, however, Ivins will use the shuttle's robot arm to remove and temporarily relocate a shuttle docking port currently attached to the hatch needed by Destiny.

The docking port, known as PMA-2, will be repositioned on the far end of Destiny after the lab attached to the station.

Curbeam and Jones, a former B-52 bomber pilot and CIA analyst, plan to stage three spacewalks to connect power, data and ammonia coolant lines between Destiny and Unity and to accomplish several other "get-ahead" tasks for upcoming assembly flights.

The Destiny lab module is moved by an overhead crane in Kennedy Space Center's processing facility. Photo: NASA

During the first spacewalk, Ivins, making her fifth space flight, will use Atlantis's 50-foot-long robot arm to slowly unberth the lab module and attach it to Unity.

She will not be able to see the docking interface and instead will have rely on verbal cues from Curbeam and Jones and television views from small cameras mounted on the helmets of the spacewalkers to achieve the proper alighment.

"I'm pretty high maintenance on this flight," Ivins joked. "We're hoping if the Cape can get the lab into the bay I can get it back out again. Hopefully, they won't have to use a chest spreader. So pulling it out of the bay with an inch or less of clearance on all sides will be the first hopefully surmountable task.

"We'll pull the lab out of the bay and it's really slow," she said. "A hundredth of an inch per second is like my max speed. So you guys could probably go and have a nice meal somewhere while I'm still pulling this thing out of the bay.

Once Destiny is clear of the shuttle's payload bay, Ivins said she will "flip it around 180 degrees. I have to fly it through a somewhat circuitous route in order to make the arm happy in order to get it into position on the node and ... hopefully, that all works."

Astronauts Curbeam and Jones wear their spacewalking suits in the traditional crew portrait. Polansky, Ivins and Cockrell have on their launch and entry suits. Photo: NASA

Jones provided a brief preview of the three spacewalks needed to hook up the lab module.

"We have three EVAs and they're all aimed at activating, berthing and outfitting the laboratory for later operations on the station," he said. "The lab is the focus of science research later on, so we need to get it hooked up to the resources on the station.

"So on the first EVA, we've got to have Marsha berth the lab to the front of the station. Then Bob and I, who've been waiting outside and doing some preparatory activities, we get to he meat of that EVA, which is hooking up the electrical and fluid connectors."

Destiny's electrical power will be provided by the P6 solar arrays installed in early December atop a structural truss known as Z1. The P6 truss also features ammonia radiators to provide cooling for critical lab systems.

Jones and Curbeam will make the power and cooling connections between the lab and the P6 truss.

"Once those critical connections are made, electrical and fluid for thermal conditioning, we can get started on the inside, in the cockpit, and start activating the lab's subsystems," Jones said.

"So really, the first EVA is actually physically moving the lab onto the station and then making sure it's safely powered up from the station and can keep alive for an indefinite period.

"The second and third EVAs are going to continue the outfitting of the outside of the laboratory," he said. "On the second EVA, we have the power and data grqpple fixture that comes over from Atlantis and gets installed on the side of the lab.

"That's the base for the installation of the robotic arm for the station that comes up on (station assembly flight) 6A. And there are some wiring and fiber optic connections we make underneath the debris shields on the Destiny lab to put that into operation."

The PMA-2 docking port will be attached to Destiny's far hatch during the second spacewalk, after Curbeam removes a large thermal cover from the hatch.

The station with Destiny added and the PMA relocated to the end of the module. Photo: NASA

During the third and final planned excursion, Jones and Curbeam will reconnect umbilicals between PMA-2 and the station and install a spare S-band radio antenna system.

Jones and Curbeam will close out the spacewalk taking turns pretending to be incapacitated to test emergency procedures for getting an injured spacewalker back into the safety of the shuttle's airlock as quickly as possible.

"We have a lot of things that have to work together, a bunch of 'sequential miracles' as we've mentioned in the past, to actually get to the finished product of the flight," Cockrell said.

"There are tight tolerances on the lab, getting it out of the bay, robotics is not a straight-forward operation with a payload with this kind of mass on it.

"This is the first time PMA-2 will have been separated from the (Unity) node for the last two and a half years," he said. "It's been bolted down with a lot of torque since it was launched back in November of '98. None of us think that's going to go just perfectly.

"Then threading the needle, getting the lab into the common berthing mechanism and then using laptop computers from the aft flight deck ... and having it drive the latches and the electric bolts to latch down the lab, there are just a lot of things that are in sequence and serial that have to work.

"So the pressure is there," Cockrell concluded, "because there are any number of things that can stop us in our tracks along the way."