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Shuttle Atlantis set for launch on its final mission

The shuttle Atlantis is poised for launch Friday on its 32nd and final planned mission, a three-spacewalk flight to the International Space Station.

KENNEDY SPACE CENTER, Fla.--The shuttle Atlantis is poised for launch Friday on its 32nd and final planned mission, a three-spacewalk flight to the International Space Station to install a new Russian module, a backup Ku-band dish antenna, and six massive batteries to replace aging power packs in one of the station's solar arrays.

The shuttle's six-man, all-veteran crew also will deliver needed supplies and equipment as NASA stages its final three shuttle missions to complete the assembly of the lab complex by late this year or early next.

Atlantis, shortly after the rollout to pad 39A, is being readied for its 32nd and final planned flight. NASA

"Twelve days, three EVAs, tons of robotics, we're putting on spares that will make us feel good about the long-term sustainability of ISS, we're replacing batteries that have been up there for a while, docking a Russian-built ISS module," said shuttle Program Manager John Shannon. "This flight has a little bit of everything.

On board for the 132nd shuttle mission will be commander Kenneth T. Ham, pilot Dominic A. Antonelli, flight engineer Michael T. Good, Stephen G. Bowen, Piers J. Sellers, and Garrett E. Reisman, who spent three months aboard the space station in 2008.

Reisman, Good, and Bowen will work in two-man teams for three planned spacewalks to install the backup antenna, the solar array batteries and other equipment. Sellers, who will operate the station's robot arm during the spacewalks, will assist Reisman on the arm during installation of the Russian mini-research module, or MRM-1, on the fifth day of the mission.

The 17,760-pound MRM-1, also known as "Rassvet," is packed with 3,086 pounds of NASA equipment and supplies and carrying an experiment airlock and European robot arm equipment that will be attached to other modules later.

Docked to the Earth-facing port of the central Zarya module, MRM-1 will bring additional pressurized volume for research and stowage and provide needed clearance between the forward Russian docking port and a U.S. storage module scheduled for attachment later this year.

The Russian module's docking system is virtually identical to the systems used by Progress and Soyuz spacecraft that dock with considerably more force than NASA typically employs. The station's robot arm cannot match that docking force, but by precisely centering the docking mechanisms, engineers are confident the Canadian space crane can get the job done.

"This module was originally designed to fly up, like all the other Russian modules, and dock under its own power, autonomously," Reisman said. "The way they do that is they have a big cone (on one module) and a big probe (on the other), they get a good running start, and it's almost like bringing train cars together. I was inside the station a couple of times when dockings occurred and you can feel her come in. It's definitely an event.

"What we're trying to do here is very different...They call it 'mini' but like many things, it's actually very big," said Reisman, who stands 5-feet-4-inches tall and is jokingly known as "Big G." "To have it on the very end of the arm, with the arm fully extended, there are a lot of dynamics at play. So the arm can't get the kind of ramming speed it normally develops under its nominal means of docking. So we're going to be restricted to coming in approximately five times slower, and that's the fastest the arm can do safely.

"What we hope to do is have very fine control and have it come right down the middle. There are a lot of people who have worked really hard, did a lot of analysis to verify this is going to work. But the exciting thing is it's never been done before and so I'm sure we'll all be watching very carefully as we bring that in on flight day five."

Ham will be watching very carefully indeed. Making his first flight as a shuttle commander, he said, "I hope that I'm the only person who's a little concerned about it, but I have to be, it's my job to worry."

"I think everything's going to work out just fine," he told CBS News. "But with any 'first' that you do, and this is the test pilot speaking, you've got to wonder about what is it that hasn't been thought about yet. And there are potentials in this scenario trying to get this on there with the arm. That makes it different."

Timelines for spacewalks tight
MRM-1 complexities aside, the timelines for the crew's three planned spacewalks are extremely tight and the excursions must be conducted in serial fashion.

During the first spacewalk on flight day four, Reisman and Bowen plan to install the backup Ku-band dish antenna atop an 8-foot-tall mast and mount an equipment support platform on a Canadian robot arm extension. During the second spacewalk, Bowen and Good will begin work to replace six 365-pound nickel-hydrogen batteries on the far left end of the station's main power truss.

"These aren't double A's," Good said. "One of my brothers likes to give me a hard time about flying up in space and changing batteries, he thinks this is not a very difficult task, not a big deal. But these are like 400-pound nickel-hydrogen batteries, they're the size of a big suitcase, probably bigger than the airlines would let you take on without charging you extra. And they're pretty tricky...The alignment and the tolerances are very tight."

Again, the robot arm will be fully extended to position the battery pallet near the work site while Bowen and Good, and then Good and Reisman, swap out the batteries using new spacesuit gear specially modified to minimize the risk of electric shocks.

"I don't want this to sound the wrong way, but it is a house of cards. if you don't get all the cards to line up just right, then all the EVAs fall apart. I trust these guys, they're awesome, they're great. But there are aspects of it that are mechanical that they cannot foresee or counter when they go wrong."

Launch from pad 39A at the Kennedy Space Center is targeted for 2:20:08 p.m. EDT Friday, roughly the moment Earth's rotation carries the firing stand into the plane of the space station's orbit. If all goes well, Ham will guide the shuttle to a docking with the space station's forward port around 10:27 a.m. on Sunday.

The next day, Reisman and Bowen will stage the first spacewalk, followed by installation of MRM-1. The second spacewalk is targeted for May 19, with the third on May 21. Atlantis is scheduled to undock from the station around 11:20 a.m. on May 23, setting up a landing back at the Kennedy Space Center around 8:44 a.m. on May 26.