NEW YORK — A company that sends wealthy tourists into space aboard Russian rockets announced last week that it has a new client, Google co-founder Sergey Brin, and a new plan for the first entirely private flight to the international space station.

Space Adventures Ltd. said Brin, a native of Moscow, had paid $5 million to reserve a seat on a future flight.

Just where and when the 35-year-old billionaire might fly is still up in the air. Since 2001, the company has sent five tourists to the space station, but it has been dreaming about other destinations, including a swing around the far side of the moon.

Brin didn't appear at the company's news conference at the Explorer's Club in Manhattan, but he said in a statement that he considered his deposit an investment in the company and suggested he hadn't decided whether to exercise his option to fly.

"I am a big believer in the exploration and commercial development of the space frontier and am looking forward to the possibility of going into space," the statement said.

Google Inc. chief executive Eric Schmidt declined to comment, calling it a personal matter.

Space Adventures also announced last week that it had reached an agreement to preserve its partnership with Russia, which had been indicating lately that its days in the space tourism business were numbered.

On each of its five previous missions, the Virginia-based company had tagged along aboard flights already scheduled by the Russians, who were willing to sell spare seats to raise cash.

Top Russian space officials, however, had expressed doubt that they could continue to offer seats, citing increased demand for trips to the space station.

The station's crew is expected to increase from three to six astronauts in 2009, and once NASA retires the space shuttle in 2010 it will also be relying on Russia to get U.S. astronauts into space.

Space Adventures said it will deal with the demand crunch by chartering an entire space flight, just for itself, with space for two clients plus a Russian cosmonaut. Russia's Federal Space Agency would still run the mission, but Space Adventures would pay for the trip and buy its own Soyuz spacecraft.

"The Soyuz to be used for this mission shall be a specially manufactured craft, separate from the other Soyuz vehicles designated for the transportation of the (space station) crews," Alexey B. Krasnov, who heads Russia's manned space program, said in a statement released by the company.

Krasnov said the private mission wouldn't interfere with the Russian space program or other missions to the space station.

The arrangement still needs to be approved by other nations involved in the running of the station.

NASA space station manager Kenny Todd said that consultation hasn't taken place. He said that since NASA is a primary partner in the space station, "it certainly wants to have an understanding of how that's going to happen and what all would be involved" in the private flight.

Space Adventures President Eric Anderson wouldn't disclose how much the mission will cost or how much a passenger might pay for a ticket. He also wouldn't say how much Brin might eventually pay for his ride into space.

The company's sixth customer, computer game designer Richard Garriott, is scheduled to go up in October after paying $35 million for his seat. He is a vice chairman of Space Adventures and the son of NASA astronaut Owen Garriott, who sits on the company's advisory board.

As for the possibility that the company might travel as far as the moon someday, the company's managing director and co-founder, Peter Diamandis, expressed optimism.

Space Adventures has been planning for a trip in which one of its craft would circle — but not land on — the moon. Diamandis said he expects to have a customer take the first such flight within five years.

The company has been advertising tickets on that flight at $100 million per seat.