A view of the space station minutes before Discovery undocked after a week-long visit. Photo: NASA TV/Spaceflight Now

The Discovery astronauts undocked from the international space station today, wrapping up a successful mission to ready the complex for delivery of a huge set of solar arrays in December and its main laboratory module in January.

"The feeling is extremely satisfying for everybody on board," commander Brian Duffy told Spaceflight Now. "We couldn't be happier with the way things went."

Running one orbit late because of minor snags Thursday, Discovery disconnected from the station at 11:08 a.m. after a full week of assembly and outfitting work that included four back-to-back spacewalks and the installation of two new components.

If all goes well, Discovery will glide to a landing at the Kennedy Space Center on Sunday, just nine days before launch of the station's first full-time crew - commander William Shepherd, Yuri Gidzenko and Sergei Krikalev - aboard a Russian Soyuz rocket Oct. 31.

From that point forward, the space station will be permanently staffed with rotating crews of astronaut/cosmonaut researchers.

"I think it's a tremendous milestone," astronaut William McArthur told Spaceflight Now in an interview from orbit. "It's almost like when you've been preparing for a big race and then finally ... the starter's gun goes off and we finally get to the business at hand.

"Bill Shepherd, Sergei Krikalev, Yuri Gidzenko, I mean we're all cheering for these guys, we can't wait for them to get up here," McArthur said. "By golly, our chests are going to swell with pride when they're up here and we know the laboratory, the station they're working in, is something we had a little hand in building."

Shuttle pilot Pamela Melroy, asked if Shepherd and company will enjoy the station's accommodations, said "let me tell you, they were good enough that we spent as much time in there as we could.

Discovery slowly backs away from the station. Photo: NASA TV/Spaceflight Now

"It's just beautiful in there," she said. "Everything is new and clean and shiny and I think one of the things we all noticed was how much more room there is. You know, the shuttle is very comfortable for us, but it is a little bit of a tight fit for a long period of time for seven crew members with EVA suits and everything.

"And we just all remarked immediately how spacious and light and airy the (Unity) node seemed and the (Zarya module) has lots and lots of storage space. We were very impressed and we think Shep and his crew are going to love it."

Discovery docked with the station last Friday. On Saturday, the astronauts attached a nine-ton, $273 million structural truss to the zenith port of the Unity module. The truss will serve as the mounting point for a huge set of solar arrays that will be attached in early December.

The Z1 truss also houses the station's main communications antennas and the four gyroscopes that will be used to keep the outpost stable and properly oriented.

A new $20 million shuttle docking port was attached to Unity's nadir, or Earth-facing, port on Monday during the second of four spacewalks to hook everything up, to ready the truss for arrival of the solar arrays and to mount tools on the station's hull.

Spacewalks were the exception during the early years of the shuttle program but as station assembly proceeds, flights with multiple EVAs will become commonplace. This steep ramp up is known as "the wall" by station planners at the Johnson Space Center in Houston.

"It is a furious pace and the wall is very real," spacewalker Leroy Chiao told Spaceflight Now. "But I think we've demonstrated that it is climbable. Through our good training and practice and all that, we were able to go out and execute the plan pretty much as we had hoped to and overcome the obstacles that did come up."

Fellow spacewalker Peter "Jeff" Wisoff agreed, saying "I think the training is very excellent, like Leroy said, and obviously, the view's a lot better when you do it for real."

Looking down at the space station clearly shows the outpost's growth from this assembly mission: the Z1 truss on the bottom and a new docking port on the top of Unity. Photo: NASA TV/Spaceflight Now

The view was particularly impressive to Michael Lopez-Alegria, who joined Wisoff for the mission's second and fourth spacewalks. During the final excursion the astronauts took turns test flying small jetpacks designed to help a lost spacewalker make it back to the station in an emergency.

"The jetpack experience was really fantastic," he said. "Being outside takes everything to another level of intensity and being untethered - feeling untethered, anyway, because we had slack in the tether - is yet a jump above that. It's the closest thing I think you can be to a human satellite and it's just awesome."

With Melroy at the controls, Discovery disconnected from the station as the two spacecraft were sailing some 240 miles above centra Brazil. Total docked time was six days 21 hours and 23 minutes.

In previous shuttle-station undockings, the station was oriented vertically with respect to Earth with the orbiter on top, its payload bay facing down. The shuttle backed away to a point directly above the lab and then, fuel permitting, looped around the lab once or twice for photo documentation.

For today's undocking, the station was oriented in a horizontal fashion, broadside to the direction of travel with Discovery on one side and Zvezda on the other.

Melroy backed the orbiter away to the northern side of the station's orbital plane and then moved to a point about 1,000 feet ahead before moving away for good.

The reasons for this so called "XPOP" separation attitude is the need to maximize solar heating on the new Z1 truss the Discovery astronauts installed last Saturday.

Late this summer, engineers discovered a possible problem with critical sensors that measure how fast the gyroscopes in the truss are spinning. The gyros will not be activated until early next year and engineers were concerned a Hall effect speed sensor could fail if one got too cold during the period they are dormant.

The space station as seen out Discovery's docking port. Photo: NASA TV/Spaceflight Now

In its current configuration, the station does not have enough power to keep all of the Z1's heaters running full bore. As a result, the outpost is being kept in an orientation to maximize solar heating.

Once the P6 solar arrays are installed in December, the station will have plenty of power for the Z1 heaters and solar warming will no longer be necessary.

But until then, Shepherd and his two crewmates will not be allowed to enter the Unity module because of high temperatures.

Discovery's crew originally planned to depart from the station one orbit earlier today. But they fell behind schedule Thursday completing internal outfitting and while they accomplished virtually all of their planned tasks, they delayed sealing off the Unity module until this morning. And that delayed the departure by about 90 minutes.

The major item on the agenda Thursday was to complete internal Z1 truss outfitting and to test the four control moment gyroscopes - CMGs - in the station's motion control system. That work took longer than expected, but the gyros checked out healthy and ready for operation.

"Everybody has been fairly concerned about the gyros and wanted to check the health of them in orbit," said station flight director Sally Davis. "I'm happy to report we have four good CMGs. They spun up to the speeds we expected them to, we made sure all of he wheel speed sensors were working correctly - and they were - we turned on the operational heaters and hopefully we'll be able to have enough power to keep them up (until the solar arrays attached)."