Grand experiment: 13 people on space station

CAPE CANAVERAL, Florida (Reuters) - Astronauts are preparing for their most ambitious experiment yet on the International Space Station: how to get along and be productive in an isolated, risky and increasingly crowded environment.

With the arrival of the U.S. space shuttle Endeavour, which is scheduled for launch at 7:17 a.m. EDT Saturday from the Kennedy Space Center in Florida, the number of astronauts aboard the station will swell to a record 13.

"I don't know what it's going to be like," said Endeavour commander Mark Polansky, a veteran of two prior spaceflights. "We know it's going to be challenging with 13 people aboard."

There's a lot more room aboard the space station since Polansky's last visit more than two years ago. Four more modules have been added to the $100 billion research outpost, which orbits about 225 miles above Earth.

The Endeavour crew will deliver and install a porch for science experiments that need to be exposed to the open space environment.

They are scheduled to reach the station less than three weeks after its live-aboard crew doubled in size to six.

Europe's Frank De Winne, Canada's Robert Thirsk and Russian cosmonaut Roman Romanenko arrived at the space station on May 29 aboard a Russian Soyuz capsule.

The trio joined Koichi Wakata of Japan, NASA's Michael Barratt and Russian commander Gennady Padalka, marking the first time that astronauts and cosmonauts from all the station partners were together in orbit at one time.

The United States and Russia lead the station partnership, which includes the European, Japanese and Canadian space agencies.

"Everyone knows what it's like to have the in-laws and friends and other family members over for the holidays for several days," Thirsk said before his launch. "There are line-ups at the bathroom, meals have to be properly coordinated. Everyone loses their personal space a little bit, but it's something we're willing to go through."

GOOD GUESTS

The space station currently has nearly 26,000 cubic feet of pressurized space, about the same as a four-bedroom home. It has three laboratories and five other modules with sleeping berths for four, two bathrooms and two kitchens.

The U.S. and Japanese modules have temporary sleeping accommodations for two additional crew members.

The visiting shuttle astronauts said they will try to be good guests, but they will need to use the station's bathrooms and galleys.

Shuttle crews typically dump urine and other wastewater overboard during flight, but during Endeavour's mission the practice will be curtailed to ensure the station's new porch stays pristine.

That means shuttle astronauts will be encouraged to bypass their ship's toilet in favor of using the station's two bathrooms.

One of the commodes is hooked up to a water recycling system that purifies urine for drinking, which the shuttle astronauts will use.

Polansky said one of the biggest problems with so many people aboard is that everyone wants to help.

"We're all type-A people and we want to get the job done. (It's like the) old adage about the cooks -- you could have too many folks trying to help and you actually do less with more, so what we need to do is make sure that we stay focused on our tasks, that we don't interfere with each other," he said.

The Endeavour crew plans to conduct five spacewalks during their 16-day flight to install the new Japanese-built porch, replace batteries on one of the station's solar panel wings and position spares on platforms outside the outpost.

The astronauts have taken extra pains to learn how to coordinate communications on radio links during the spacewalks, which include simultaneous operation of three robotic cranes.

"I'm sure there's going to be growing pains, there's no doubt about it," said Polanksy. "But it's going to be exciting to have that many folks up there."

(Editing by Jim Loney and Paul Simao)