The seat liners are key because the escape module -- if needed -- would land on the ground and the seats need to fit precisely to properly protect a returning astronaut or cosmonaut, according to Mark Ferring, the flight director for Alpha.

CNN: newcrew

Earlier Thursday, new Alpha commander Frank Culbertson and Russian flight engineers Vladimir Dezhurov and Mikhail Tyurin beamed down a message marking the one-thousandth day in space for the first component of the space station, the Russian-built Zarya module.

CNN: Spacewalkers hang experiments on Alpha

Prior to this shuttle delivery flight, there were sleeping quarters for only two Alpha residents.

CNN: Space station handover ceremony delayed

Despite the exercise regimen, which lasted at least an hour each day, the old Alpha crew can expect weeks of physical therapy to regain muscle and bone strength lost during the flight, the second longest in NASA history.

CNN: Alpha astronauts: Trip to Mars is doable