Sergey Brin says he is a big believer in space exploration
Google co-founder Sergey Brin has made a $5m (£2.5m) down payment to book a seat on a future orbital space flight, a US space tourism company has said.
Space Adventures says it is planning the first private space flight to the International Space Station in 2011 in a deal with the Russian space agency.
The initial payment gives members a first option on a seat on the mission.
It will go towards flight costs, which could be $35m or more, Space Adventures CEO Eric Anderson said.
"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," Mr Brin said in a statement.
In the past, Space Adventures has sent private tourists into space by buying seats on Russian missions to the International Space Station (ISS).
But the 2011 mission will be different.
"The Soyuz to be used for this mission will be a specially manufactured craft, separate from the other Soyuz vehicles designated for the transportation of the ISS crews," said Alexey Krasnov of the Federal Space Agency of the Russian Federation.
"This private mission, flying two Space Adventures clients at once, will not interfere with the implementation of the ISS programme or the obligations of the Russian space agency; on the contrary, it will add flexibility and redundancy to our ISS transportation capabilities."
Google has already shown an interest in space exploration by becoming one of the sponsors of a $30m prize designed to stimulate research into low-cost space missions, including landing a vehicle on the Moon.