The heart, lungs and other major organs typically weaken, making exercise a bit exhausting for returning astronauts and cosmonauts. Muscles atrophy from lack of use and the skeletal system withers away, resulting in both a loss of strength and bone mass.

The inner ear also is adversely affected, so it's a bit tougher than usual to keep one's balance during the first few days or weeks after a return from outer space.

But all three of the Expedition Two crewmates exercised vigorously -- and daily -- during their long stay on the station. They ran on a treadmill, pedaled stationary bikes and worked out on a resistive exercise machine that enabled them to do orbital calisthenics.

And doing so, Voss said, helped the trio stay in relatively good shape prior to the start of a lengthy physical rehabilitation program that began shortly after their Aug. 22 return to Earth.

"I seem to be recovering pretty quickly. Once in a while, I'll feel just a bit of wobbliness, but most of the time I'm doing all right and feeling fairly normal strength-wise," Voss said.

"If we're doing something strenuous -- like yesterday I did a bicycle ergometer test -- it's more fatiguing than I remember it being before flight."

Added Helms: "I'm just getting my Earth legs back."

Some astronauts and cosmonauts tend to have trouble sleeping after a long stay in weightlessness, and some have vivid dreams of flying or floating about. That hasn't been the case, however, for Voss.

"I think I've been too tired to do much dreaming, and I don't recall having any (dreams) since I've been back," the veteran astronaut said. "I've slept very soundly -- maybe that's part of being tired after a long flight."

For Voss, the biggest surprise he's encountered since returning to Earth was an initial loss of appetite. After five-and-a-half months of relatively bland space food, he had been craving an old-fashioned hamburger. But upon his return, he was too woozy to eat.

"I had been looking forward to having it for some time, and they had one ready for me the very first evening that we got back," Voss said. "But I just had no appetite at all."

So he waited for a day and then got reacquainted with another American meal: Leftovers.

"I had (the hamburger) the next day for lunch," Voss said. "And it was pretty good when I tried it then."

Launched March 8, Usachev, Helms and Voss started up a suite of science research experiments at the station and also carried out two key construction jobs.

With an assist from visiting shuttle astronauts, the Expedition Two crew installed and activated the station's $600 million Canadian robot arm and a $164 million airlock, capping the first full phase of the 16-nation outpost construction project.

Coupled together, the components will enable station crews to perform spacewalking assembly or repair work without a visiting shuttle present.

Usachev, 43, soon will be heading back to Moscow for 10 days of medical tests and mission debriefings. Then he and his family will take a three-week vacation.

Voss, 52, will be easing back into life at his suburban Houston home while he and Helms continue a 45-day rehabilitation program at NASA's Johnson Space Center. And for Helms, also 43, the readaptation to life back on Earth will include reestablishing a terrestrial abode.

Single and without children, Helms closed up her apartment and moved all her belongings into long-term storage before setting sail for the station. She's staying with friends now, but it won't be long until she has a place to call her own.

"I have found an apartment and have done everything but sign the lease," she said. "I'm all ready to move in during the middle of September."

Still to come: A new car hunt to be financed with money saved while she was away.

"I have not yet started the car search. I think that'll have to wait," Helms said.

"We're concentrating on things we have to accomplish in the next 10 days, and then after that we'll get a little bit more of a relaxed schedule, and I'll have a chance, maybe, to go looking for that new car."