"That's very nice work," shuttle pilot Rick Sturckow told the spacewalkers from inside the crew cabin of Discovery. "It looks like you guys did a good job there."Shuttle skipper Scott Horowitz then began hoisting the pallet out of its cradle with Discovery's 50-foot (15-meter) robot arm so it could be attached to the power tower, which serves as the base for station's massive American solar wings.
Hanging onto handrails on the tanks, Barry and Forrester headed off on a four-story "elevator ride" up to the truss-like tower as Horowitz lifted the pallet up to its mounting point.
"Okay, Pat and Dan, everything is going really great. Are you for a ride?" Horowitz asked.
"Ready to ride," Barry replied.
"Fasten your seat belts," Horowitz said.
The bulky tanks hold a reserve supply of ammonia, the fluid used in station radiators to cool outpost electronics. The attachment of the tanks is the first of two tasks that Barry and Forrester are expected to carry out.
Two suitcase-sized trays filled with advanced materials and spacecraft components also are to be set out during the sortie.
The idea is to test paints, coatings, solar cells, sensors, switches, lenses and mirrors that one day might be used to build next-generation spaceships, solar sails, communications antennas and orbital telescopes, among other things.
Once opened by the spacewalkers, the suitcases - which also include seeds, spores and various types of bacteria - will be exposed to the harsh space environment for more than a year before the trays are return to Earth for scientific evaluation.
The planned 6.5-hour excursion began to unfold after the station's newly arrived crew marked the 1000th day in space for the first building block of the outpost - the Russian space tug Zarya, which was launched Nov. 20, 1998.
Also known by the Russian acronym FGB, the station cornerstone connects the U.S. and Russian sections of the outpost, which now features four linked wings that stretch 171 feet (52 meters) from end to end.
"The FBG is a small kernel that began the station," station skipper Frank Culbertson said in live commemorative message beamed down to flight engineers at Mission Control Centers in both Houston and Moscow.
"It joins the Russian segment and the U.S. segment very securely and soundly and is a very terrific foundation for the station.
Flanked by Russian cosmonauts Vladimir Dezhurov and Mikhail Turin, Culbertson and his crewmates were floating in a narrow hatchway within Zarya at the time.
"We're very proud to be in it at this moment and wishing everybody happiness and congratulations on the first 1,000 days," Culbertson said. "And we're looking forward to the next 1,000 days."
The station's U.S. Unity module was launched and linked to Zarya in December 1998, but outpost construction came to a standstill until the long-delayed Russian Zvezda crew module finally was launched in July 2000.
Since then, NASA and its 15 international partners have added the first piece of the station's skeletal truss, the U.S. electric power tower, the U.S. Destiny science laboratory, a Canadian robot arm and a U.S.-built airlock.
And if all goes as planned, the 132-ton outpost - which already is equal in mass to Russia's former Mir space station - will double in size again over the next 1,000 days.
A Russian docking compartment is to be added to the station in mid-September, and then over the course of the next three years, the U.S. will stage a series of shuttle flights aimed at raising the rest of the outpost's 356-foot (108-meter) central truss.
Three more U.S. electric power towers also will be added in that time, paving the way for European and Japanese research facilities to be launched to the outpost in 2004 and 2005.
Culbertson and his cosmonaut colleagues will oversee the addition of the Russian docking compartment, carrying out three spacewalks to outfit it externally.
The so-called Expedition Three crew is scheduled to return to Earth Dec. 9.
Visiting shuttle Discovery will remain at the station until early next week.
Barry and Forrester will carry out a second spacewalk Saturday to rig up power cables outside the Destiny lab, and a day later, the astronauts will stow an Italian moving van back in the shuttle's cargo bay.
Now attached to the Unity module, the cylindrical shipping container is being loaded up with luggage, surplus station gear and garbage for a return trip to Earth.
Discovery is slated to depart the station Monday with an outgoing outpost crew that includes Russian cosmonaut Yuri Usachev and American astronauts Susan Helms and Jim Voss, who have been in space since March.
With the Expedition Two crew in tow, the shuttle and its four space taxi drivers are scheduled to touch down at Kennedy Space Center at 12:48 p.m. EDT (1648 GMT) next Wednesday.
advertisement
