Floating in the Quest airlock module, space station commander Peggy Whitson and Dan Tani switched their spacesuits to internal battery power at 5:10 a.m. today to kick off a planned six-hour 40-minute spacewalk to route power and cooling to the new Harmony module. A second excursion will be needed Saturday to finish the job and help clear the way for launch of shuttle Atlantis Dec. 6 on a long-awaited mission to deliver a European laboratory module.

"A nice day at the office here," Tani said as he floated out of the airlock high above the north Atlantic Ocean. "Oh, it's just an awesome view!"

This is the 98th spacewalk devoted to station assembly and maintenance since construction began in 1998, the 21st so far this year and the second for the Expedition 16 crew. Whitson and flight engineer Yuri Malenchenko carried out the crew's first EVA on Nov. 9, preparing the station's shuttle docking port for attachment to Harmony.

With that work complete, the docking port was robotically removed from the front of the Destiny lab module on Nov. 12 and bolted to Harmony, which was initially mounted on the left-side of the central Unity module. The assembled Harmony/docking port "stack" then was moved to its permanent home on the front end of Destiny two days later.

The goal of today's spacewalk by Whitson and Tani is to make a variety of electrical connections between Harmony and Destiny to route solar array power to the new module. They also will unstow and mount ammonia cooling lines that will run in a long tray from the complex's main power truss, across the Destiny module to the interface with Harmony.

A second spacewalk Saturday will mirror today's work, giving Harmony the power and cooling necessary to support European and Japanese research modules that will be attached to the module's forward ports.

"We think we've got a good plan together, the teams on the ground have really helped us out and we feel ready," Whitson, the station's first female commander, said Monday.

"Peggy's always cool. I'm just trying to do the collected part," Tani joked. "We are excited and these EVAs I expect to be tough. When we practice them in the water, I always come out thinking, boy those are really some pretty challenging tasks that we're being asked to do. So we're looking forward to it.

"Plus, we know that we are in the critical path to getting the node (Harmony) fully activated so the next shuttle can launch. So there's a little bit of pressure there, but we like the pressure and we're really looking forward to getting outside and getting the work done."

After leaving the station's airlock, the spacewalkers will meet on the lower side of the central S0 segment of the solar power truss to remove an ammonia shunt jumper from coolant loop A, permitting attachment of the loop A cooling line tray later in the EVA.

After reconfiguring electrical connectors in the P1 solar array truss segment and removing caps from ammonia lines leading into Harmony, Whitson and Tani will unstow the hinged 18.5-foot-long 300-pound loop A tray from its storage location on the central solar array truss.

The loop A tray will be mounted on top of the starboard avionics tray on the right side of the Destiny module. With the tray in place, the spacewalkers will make six ammonia fluid line connections to complete the loop A supply and return lines: Two connections between the S0 truss and the tray; two at a hinge in the tray; and two more between the end of the tray and Harmony.

With coolant loop A in place, Whitson and Tani plan to turn their attention to making electrical connections. Tani will connect 11 cables on the other side of the lab module and Whitson will connect four cables between the shuttle docking port and Harmony.

Saturday's spacewalk is virtually identical, with work to connect the loop B cooling lines, make additional electrical connections and to prepare Harmony's right-side port for the upcoming attachment of Columbus.

"Once we get through these EVAs, we still have some logistics-type tasks, nothing I would consider very sexy or noteworthy, but still things we need to get done between now and 1E (the Columbus flight)," said Kenny Todd, space station integration and operations manager.

"We've been on a tight schedule trying to get to this launch Dec. 6, so we are reviewing daily our tasking to ensure we're only doing those things we need to do to be able to support this flight in early December. We're all very, very excited about getting the Columbus module on orbit."

The first of the Expedition 16 crew's three spacewalks had been scheduled to be carried out during the shuttle Discovery's recent visit. But unplanned work to fix a mangled solar array forced mission planners to defer the station crew's spacewalk to Nov. 9, after the shuttle's departure.

Whitson, Tani and Malenchenko have been working pretty much non stop to get Harmony moved, hooked up and prepared for Columbus in time to permit the Atlantis flight during a short eight-day launch window that opens Dec. 6.

"They are not going to have Thanksgiving off," said station flight director Holly Ridings. "The crew knew that this month of November was going to be very, very challenging. And so they said right up front, if it works out that we need to work on Thanksgiving, we are more than happy to do that. And it did work out that way. So they will be working on Thanksgiving with a lot of us here working as well to support them."

That doesn't mean they won't take time off for a traditional Thanksgiving Day meal in space. During a TV downlink Monday, Whitson and Tani took time to beam down a holiday greeting.

"We wanted to say happy Thanksgiving to all our NASA (television) viewers," Whitson said. "We feel particularly privileged and thankful to be up here on board the international space station this Thanksgiving and we're looking forward to our activities this week - we have a busy week with EVAs - and we hope that you also are having a great Thanksgiving."

Said Tani: "My family, we gather for Thanksgiving and we spend a minute just thinking about the things we're thankful for and of course, I'm thankful for the continued health of my family and my loved ones. Also this year, I'm thankful that I'm safely on the space station, conducting our mission successfully and having a great time doing it. I'm thankful for all the people on the ground who support us and who are tireless in their devotion to the space station program, to the space program in general and to the crew. And I'm thankful for Peggy, my crewmate ... and Yuri.

"When we think about Thanksgiving, we think about the Pilgrims coming to the New World and expanding their knowledge of their universe, making new discoveries and making a better life for themselves. And Thanksgiving was an opportunity to be thankful for their survival of a very difficult time. And I think maybe where we are in the space program, of human space adventures, and thinking that well, here we are safely on the space station, we have setbacks but we solve them and hopefully this is the start of our generation, or our world, expanding our knowledge and learning how to live in space and expand our knowledge outside of low-Earth orbit."

Whitson then took the microphone and said, "So we would like to wish everyone on Earth a happy Thanksgiving, and especially our NASA family. We're thankful to be part of that family."

The two astronauts then showed off some of the food they enjoy in space, including Thanksgiving Day fare, including freeze-dried shrimp cocktail - "it's a favorite of almost everybody on board the station" - and Russian canned lamb and vegetables.

Along with sliced oranges, Tani showed off a package of Italian ham sent up by his family and miniature, bite-size loaves of Russian bread that "are delicious complements to our food."

"Finally, we don't go anywhere in the universe without chocolate," Tani said as Whitson let M&M candies float free. "These are the popular candy-coated chocolates and they're popular because of the color and the fun. I think they say they melt in the mouth and not on the lab."

Holding up an empty bottle of hot sauce, Whitson said: "Our motto on board the station is, it's all about the sauce. The best part of eating here is you have to have the right sauce to put on it and typically, the hotter the sauce, the better. This one obviously is our favorite!

"So happy Thanksgiving to all of you on the ground, we're thrilled to be here and have the opportunity to continue our assembly and we wish all the best for our friends and family and the NASA family as well. Thanks so much."