Station skipper Bill Shepherd, as a result, uncovered the research center's "window-on-the-world" for the first time. Then colleague Sergei Krikalev filmed the spacewalking duo though the 20-inch (50-centimeter) porthole as they wrapped up a highly successful excursion outside the $1.4 billion U.S. Destiny lab.

Shepherd "said it was an awesome, awesome shot," Atlantis pilot Mark Polansky told Curbeam and Jones toward the end of their six-hour, 50-minute spacewalk. "He's talking Oscar."

"We're on a roll," Ivins noted earlier as her two crewmates marched through the second of three spacewalks planned for the shuttle's weeklong visit to the station.

And as it turned out, it was a banner day for NASA elsewhere in the solar system, too.

The agency's $223 million NEAR-Shoemaker spacecraft touched down on the barren, rocky surface of Eros, successfully completing history's first landing on an asteroid.

What's more, the plucky craft beat tremendous odds by landing intact and transmitting pictures back from the surface of Eros, some 196 million miles (313.6 million kilometers) from Earth.

"Good news... NEAR-Shoemaker landed on Eros successfully and signals show that the spacecraft is intact," astronaut Gerhardt Thiele told the joined shuttle-station crews from NASA's Mission Control Center at Johnson Space Center in Houston.

"That's fantastic, Gerhardt," replied Jones, who was raised in Baltimore, Md., near Johns Hopkins University Applied Physics Laboratory, which built and controls the craft.

"It's just really an amazing place for one of our spacecraft to be, and I hope we'll have some astronauts following to the asteroid in just a few years."

The amazing day at the station got off to a swift start as Ivins snatched a shuttle docking port from a temporary storage spot on an outpost truss and then fixed it to the front door of Destiny.

The conical port had been removed from the end of the station's Unity module Saturday to clear the way for the installation of Destiny, the first of six science labs that eventually will be launched to the station.

Curbeam and Jones ventured outside the station to give Ivins a spacewalking assist.

~

Jones scaled the 17-story station to loosen a latch holding the port to the truss. Curbeam, meanwhile, found himself wrestling with large white protective covers that he had removed from a berthing mechanism at the front of the lab.

"All right, Bob, I see you encased in - it kind of looks like a hoop skirt," Jones said as Ivins began carefully inching the shuttle docking port away from its storage spot.

"Don't make me laugh," said Ivins, who was trying not to ding the docking port at the time.

Slowly but surely, Ivins then swung the port down toward the Destiny lab, pausing for a short time to allow Curbeam to ready the berthing mechanism.

"Sorry to slow you down. But I appreciate you waiting," Curbeam said.

"For you, anytime," Ivins replied.

NASA officials considered the move crucial to the $60 billion station construction project, a joint effort of 16 nations on four continents.

The station's only other shuttle docking port is located directly below the 16-ton Destiny lab. Consequently, new additions can't be mounted on the outpost from shuttles parked there because the bus-sized research center would block the way.

By mounting its twin on the forward end of Destiny, NASA now can press ahead with a highly choreographed series of 40 missions still required to finish the growing station, which eventually span an area nearly as large as two football fields.

The spacewalkers also had another crucial job on their to-do list Monday: Installing a specially designed grapple fixture on the outside of the lab.

The pin-like device had to be put in place so that a Canadian-built construction crane can be mounted to it during a shuttle mission now scheduled for launch April 19.

Known as the Space Station Remote Manipulator System, the sophisticated robot arm will be capable of inch-worming from work site to work site outside the outpost - an unprecedented capability key to completing station construction.

~

With those two prime jobs done, the spacewalkers moved on at a relatively rapid pace.

They set up a safety tether slidewire and small work platforms that future spacewalkers will use when doing maintenance work outside the lab.

They installed a debris shield that will help protect the lab from micrometeorites and orbital debris, and they placed protective covers on the trunnions that were used to secure the research center in the shuttle's cargo bay during a thundering launch into space.

The work went so fast that Curbeam and Jones took on a couple of extra jobs, routing power and data cables between the docking port and the lab and installing the lab window shutter.

"Tom and Beamer, you guys have done an outstanding job today, and we got a lot done," Polansky told Jones and Curbeam as they prepared to reenter the shuttle. "So why don't you come on inside and we'll give you something to drink and a hot meal."

"Sounds like an offer I can't refuse," Jones replied.

The station's resident crew, meanwhile, had a productive day too.

Working with cosmonauts Krikalev and Yuri Gidzenko, station commander Shepherd powered up the outpost's four fuel-saving gyroscopes for the first time - a move made possible now that associated computer control equipment has been activated inside Destiny.

Delivered by a visiting shuttle crew last October, the domed-shaped devices will greatly reduce the amount of rocket propellant needed to keep the station properly positioned in orbit.

Shepherd and company will continue outfitting the Destiny lab Tuesday while the shuttle crew takes most of the day off.

Hatches between Atlantis and the station will remain closed to keep atmospheric pressure aboard the shuttle lower than that of the outpost, reducing prep time for a spacewalk Wednesday.

Astronauts routinely breathe pure oxygen prior to a spacewalk to rid their bodies of nitrogen, a move essential to avoiding the type of decompression sickness that scuba divers call "the bends." That so-called "pre-breathing procedure" will take only 45 minutes - rather than four hours - due to the lower pressure aboard Atlantis.

Curbeam and Jones will head out on that third and final spacewalk at 10:18 a.m. EST (15:18 GMT) Wednesday. The main job during that sortie will be to stow a spare communications antenna outside the station.

Atlantis remains scheduled to depart the station Friday after a final farewell and hatch-closing ceremony set for 7:18 a.m. EST (12:18 GMT) that day. The shuttle and its crew are due to land at Kennedy Space Center at 12:52 p.m. EST (17:52 GMT) Sunday.