"I think the toughest thing is to see folks kind of coming and going for a week, and not really having any down time to sit down and relax," Shepherd told reporters in a space-to-ground news conference Thursday.

"We did a little bit of yakking last night -- it was very good. And I guess the hardest part is just seeing crews depart without really having a lot of time to socialize."

The Atlantis astronauts docked at the station last Friday and met up with Shepherd and his two Russian colleagues -- Yuri Gidzenko and Sergei Krikalev -- later that day.

A weeklong flurry of work, however, followed as the shuttle crew mounted the Destiny lab and carried out three spacewalks primarily aimed at activating the new science center.

The joined crew spent the day Thursday hustling supplies and equipment to the station from Atlantis, marking only the third time the astronauts and cosmonauts were able to get together.

Hatches between the spacecraft had remained shut during much of the shuttle's visit to keep atmospheric pressure aboard Atlantis lower than that of the outpost, reducing prep time for the three spacewalks.

The shuttle astronauts, however, said they enjoyed the limited amount of time they had to spend with Shepherd and company and were impressed with the sheer size of the growing outpost, which now stretches 171 feet (52 meters) from end to end.

"When we [first] came through the hatch, we saw three smiling faces, three crewmembers that were obviously enjoying themselves on this fine station," Atlantis commander Ken Cockrell said, adding that the astronauts "particularly enjoyed the change of scenery" between U.S. and Russian segments of the outpost.

"It shows a little bit of the culture of each of the countries involved, and it's very refreshing and invigorating to see the mixing of cultures and the sharing of ideas."

With Atlantis pilot Mark Polansky at the controls, the shuttle will pull out of the station about 9:06 a.m. EST (14:06 GMT) and then fly a half loop around the outpost before starting their trip back to the planet.

A spaceflight rookie, Polansky said he's looking forward to the opportunity to take control of the $2 billion spaceship for the first time. "It's just sort of a docking in reverse, and so I think the main thing is we'll just take it very slowly," he said.

His shuttle crewmates will be snapping pictures and capturing video of the station before Polansky fires the shuttle's onboard jet thrusters about 9:47 a.m. EST (14:47 GMT), propelling Atlantis on its way home.

"We don't see a whole lot of the space station while we're docked," said Atlantis mission specialist Marsha Ivins. "So whatever we can see we'll be taking pictures of."

The shuttle and its four-man, one-woman crew -- which also includes spacewalkers Robert Curbeam and Tom Jones -- are due to land here at Kennedy Space Center at 12:52 p.m. EST (17:52 GMT) Sunday.

The early weather forecast is a bit iffy. Meteorologists are predicting a chance of rain both at KSC and a back-up landing site at Edwards Air Force Base in California. Consequently, the astronauts could be forced to remain in space an extra day.

Weather at both sites, however, is expected to clear up Monday before deteriorating again on Tuesday.