"As you come into the house, one of the first things we have, of course, is a washroom with all the facilities," Altman said, as he floated from one end of the 13-metre cabin to the other.
Astronaut Scott Altman gave a video tour of the station's newest component - the Zvezda module.
The crew of the space shuttle Atlantis have been in orbit since Friday fitting out the module for its first full-time residents who should arrive at the beginning of November.
"As you come into the house, one of the first things we have, of course, is a washroom with all the facilities," Altman said, as he floated from one end of the 13-metre cabin to the other.
Zvezda will act as the "brains" of the space station in the early years of its construction. It controls the life-support systems, maintains the platform in its correct orbit and offers a docking port for vehicles coming to and from the station.
But the module is so heavy - about 19 tonnes - the Russians had to strip it for its July launch. As a result, Zvezda flew with only five of eight batteries and the Atlantis crew have spent the first part of their mission installing the missing units.
Rubbish bags
"It's really beautiful," shuttle commander Terrence Wilcutt said of the module.
"About any astronaut I know would be happy to spend time up here."
Some items, such as the batteries and a toilet, need to be fitted. Other items, such as office supplies and rubbish bags, need to be stacked away.
The first, permanent crew on the ISS, Bill Shepherd, Yuri Gidzenko and Sergei Krikalev, will go up to the station on a Soyuz capsule from the Baikonur Cosmodrome in Kazakhstan in late October for a four-month "shakedown" mission.
The ISS, a joint venture involving the United States, Russia, Europe, Japan and Canada, is expected to cost $60bn when completed, perhaps by 2006.
This Atlantis trip marks the 99th mission by a space shuttle.