Another Space Adventures client, Greg Olsen, who made millions in the sale of his camera technology company, Sensors Unlimited, is preparing to visit the space station for several days in October. Of the Moon trip, he said, "It's certainly intriguing, and it's something I'd like to do."

Will he buy a ticket, then? "One trip at a time," he replied.

The trip seems feasible, said Dr. John M. Logsdon, director of the Space Policy Institute at George Washington University. "As a nontechnical person, I don't see any technical showstoppers," Dr. Logsdon said, "if people are crazy enough to do it."

And, he added, it would make "a lot of money for the Russians."

Christopher C. Kraft, a former director of the Johnson Space Center, said his feelings about the enterprise were mixed. "I think it would be a fantastic journey," he said. "I could see why, if I had the price of the ticket and could use the money that way, that it would be tempting to go."

But Mr. Kraft added that the flight would be cramped and probably extremely unpleasant. With three people in a small Soyuz craft for an extended trip, he said, "I imagine that you could endure that, but, man, it would be tough."

Mr. Anderson of Space Adventures said the craft had about as much room as a sport utility vehicle. "Will it be cramped? Yes," he said. "But will it be doable? Yes."

He noted that the Gemini capsule was smaller than the Soyuz, and that the astronauts James A. Lovell and Frank Borman orbited the Earth for 14 days in the Gemini 7 mission in 1965.

But Mr. Kraft, who was the flight director for that mission, recalled that Mr. Lovell and Mr. Borman were miserable. They complained bitterly that the trip was like "14 days in a men's room," and Mr. Kraft said that he had to talk them out of ending the mission early. "They wanted to get out of there," he said.