Lost supplies of critical medicine. Computer failures. Even unannounced alien visitors. All on four hours of sleep. And, officially, it's not even Day One yet on the Red Planet. Five scientists and a reporter locked themselves away Monday for a two-week stay in an isolated area of Utah for a research project sponsored by NASA and the Mars Society, an organization advocating exploration of the fourth planet as soon as possible.

The goal: simulate the conditions of a restrictive encampment on the Mars surface, add some top-flight scientists from around the world, and see what happens. Perhaps problems discovered during an exercise on Earth could play a critical role in preventing a crisis in space.

"This rotation is especially interested in planning," said Dr. William J. Clancey, a NASA scientist who is commanding the mission at the Mars Desert Research Station. "Can we plan our work for several days in advance, at least, so Mission Support will have enough details to help us."

Dr. Clancey, 49, is chief scientist for Human-Centered Computing at NASA's Ames Research Center in Sunnyvale California.

During the next two weeks, his crew will bunk in an unusual two-story structure that looks like a cross between a white grain silo and a stubby Apollo space capsule. The stark, reddish terrain appears eerily similar to the Martian landscape.

The crew can emerge only in tightly controlled circumstances, wearing fabricated spacesuits and communicating via handheld radios with their fellow crew members inside their temporary home away from Earth. Talking with Mission Control during an actual mission to Mars would be pointless, when a reply from such a distance would take 10-40 minutes.

The other members of the crew on this mission are:

• Dr. Vladimir Pletser, 46, is a native of Brussels, Belgium. He is an astronaut candidate for Belgium working at the European Space Agency and is also project manager for an instrument being developed for the International Space Station.
  
  
• Dr. Nancy B. Wood, 60, an experimental scientist with a doctorate in microbiology from Rutgers University. She is interested in how microorganisms adapt to harsh environments, such as could be found on Mars.
  
  
• Jan Osburg, 30, an aerospace engineer at the Space Systems Institute in Stuttgart, Germany. His specialty is human spaceflight and design of inhabited space systems.
  
  
• David Real, 49, a journalist for Belo Interactive and a former reporter and assistant Metro editor for The Dallas Morning News. He and Dr. Clancey were roommates at Rice University in the early 1970s.
  
  
• Andrea Fori, 32, a planetary geologist and systems engineer with Lockheed Martin Space Systems Co. in Sunnyvale, Calif. She helped choose a landing site for the first NASA mission designed to bring back rocks from Mars.

After four hours of sleep, the crew boarded two vans jammed with equipment and provisions and headed toward the Hab to relieve the current crew, the fourth to make a two-week stay. Less than two hours later, Dr. Judith Lapierre, a space scientist at the University of Quebec in Hull, handed command of the Habitat to Dr. Clancey, and a new chapter had begun. It didn't begin auspiciously. A crew member discovered that one of his bags containing vital prescription medicine had been lost. Fortunately, another bag carried his backup medication.

Attempts to hook up the crew's computers to the base station were unsuccessful. By choice, there is no telephone service available, in order that the project may more closely mimic the isolation that crews will face on Mars. So the Habitat's satellite dish provides the only authorized connection to the outside world via the Internet, and computer networking is vital.

After several hours of unpacking, the crew met to learn the rules of everyday life on the station and to assign mundane chores, such as cleaning toilets and cooking dinner.

Our organizational meeting was interrupted several times by visitors who lived nearby and had learned of the Mars mission. They would be our last for the next two weeks.

The day ended shortly after midnight with an exhausted crew, and no solution to our computer problems.

The next day, however, would officially kick off the simulation. On Monday morning, the hatch would close on planet Earth and the crew would open the doors on its new mission: exploring a future on Mars.