CAPE CANAVERAL, Fla. - The crew of the International Space Station (ISS) is more than halfway through its planned four-month-long mission, but a major psychological barrier is approaching: the so-called "three-month wall."

Separated from family and friends -- and prohibited from going outside -- space travelers have easily succumbed to depression and feelings of isolation. The condition has historically set in among astronauts and cosmonauts who stayed in space for months at a time.

NASA managers say they have the cure, however, and are confident the Expedition One crew will not suffer the same symptoms as their three-month anniversary passes February 2.

Members of the STS-97 Endeavour crew and the Expedition One crew greet each other in the Unity module after opening the hatches between the shuttle and the International Space Station on Dec. 8, 2000.

The measures include:

• Allowing more time for the men to talk by videophones to their Earthbound families.

• Watching movies or listening to music using entertainment equipment designed to fly aboard the station.

• Hosting regular visits from other crews who bring with them fresh faces, as well as small gifts and messages from home.

Astronaut Bill Shepherd and Russian cosmonauts Sergei Krikalev and Yuri Gidzenko have been living inside the 102-foot-long outpost since docing on November 2.

The first month was spent in only 84-feet of that space because the Unity module was too cold for crewmembers. The situation changed when the station's power supply was boosted in December by the visiting crew of shuttle Endeavour, who installed a new electricity-generating solar wing.

Imagine living in an efficiency apartment 24 hours a day, seven days a week, with two other people.

Thee are no trips to the store -- no chance to go out for a breath of fresh air.

After a month, the porch is available, but still no fresh air. Add to the apartment a vast collection of boxes that clog rooms and hallways, plus noisy machinery and sputtering communications with the outside world.

~

NASA spokesman Rob Navias said the space agency took steps to overcome any potential problems on the space station, based -- in part -- by lessons learned during long-duration visits by NASA astronauts to the Russian space station Mir during the late 1990s.

Astronaut Shannon Lucid said it did not take long for loneliness to set in during her Mir flight. Lucid, who holds the American record for long-duration space flight, spent six months aboard Mir in 1996.

Endeavour commander Brent Jett (left), Russian cosmonaut Sergei Krikalev and Expedition One commander Bill Shepherd are seen on the flight deck of the shuttle as the station crew is given a fresh look at the new solar arrays on Dec. 8, 2000 shortly after the hatches between the two ships were opened.

"It's really good to be busy," Lucid said recently. "The people on station need to feel like they have some control of their time. You can't micromanage a station mission."

Jerry Linenger, also a Mir astronaut, complained frequently that NASA's ground controllers were pressing him to do too much, too fast. Other Mir astronauts echoed those feelings, plus a sentiment of being out of touch with everyone on Earth.

It also was common for the Americans to feel detached from their cosmonaut hosts on Mir, adding further to the mental block.

The American program, which hadn't operated a space station since the 1973-74 Skylab program, applied several lessons from the Russian space program, which has flown cosmonauts in space nearly continuously since Mir's 1986 launch, and for many long-duration missions on Salyut space stations before that.

After seeing their astronauts become recluses and experience despair during flights to the Russian Mir space station, NASA began making changes to the desgin and flight planning for the new outpost.

"This is so much vastly improved over Mir," Navias said. "What we learned from Mir is that if the crew has a great deal of creature comforts, it won't fall into isolation."

Unlike its Mir predecessor, the ISS has a more robust communications network.

Soon after boarding in November, Shepherd and his crew quickly set up a computer-mounted camera that allows them to talk to ground controllers anytime the station flies over an appropriately-equipped ground station.

That system will expand greatly this month with the anticipated addition of the 28-foot-long Destiny science laboratory.

~

Computers inside Destiny will manage an antenna system on the station that is supposed to allow images as clear as a television to be beamed back and forth to Earth.

Even without new amenities, Navias said Shepherd's preparation for the psychological demands of a long mission has benefited from training intensely with Krikalev and Gidzenko in the four years leading up to the mission.

Expedition One

Look here for the latest news about the first crew to live and work aboard the International Space Station.

Plus, there is plenty of work for the three men to do. They routinely delve into the bowels of the station, screwdrivers in hand, chasing glitches.

Shepherd, a former Navy SEAL, said recently that work is his best way to get through bouts of depression. One of his hobbies on Earth is working in his garage, so he routinely grabs a tool and checklist and heads off to repair station parts even on his days off.

SEALs also undergo severely challenging psychological tests during their training.

This first station crew also benefits from shuttle visits, the next of which is scheduled take place in two weeks.

When Endeavour arrived at the station last month, Shepherd, Gidzenko and Krikalev got a chance to leave the station and float around the inside of the shuttle. They also enjoyed an all night rap session with their colleagues.

They'll get the same opportunity when Atlantis arrives later this month.

"This crew feels very much in touch," Navias said.