The economic downturn has not dampened rich people's enthusiasm for space tourism, the world's first commercial space flight company says.

"Business is good," Eric Anderson, chief executive of privately owned Space Adventures, told Reuters on the sidelines of the World Economic Forum in the Swiss ski resort of Davos.

The US company has sold seats worth about $175 million on Russian rockets to the International Space Station and is preparing to send Hungarian computer software executive Charles Simonyi into space for the second time in March.

His $35-million trip will be the seventh arranged by Space Adventures since US multimillionaire Dennis Tito paid for a trip into space in 2001.

Such journeys could be threatened by Russian plans to double the size of the space station's professional crew although Space Adventures reached a deal with Russia's Federal Space Agency last year to launch its own private trip to the station in 2011.

"Access to Soyuz seats is becoming more difficult, which is why we purchased our own mission," Anderson said, referring to the Soyuz spacecraft used by Moscow.

Several customers have put down deposits for future space travel, including Sergey Brin, co-founder of US company Google.

Anderson is hoping to drum up more business among the world's business elite in Davos this week but customers should not expect any bargains because of the global financial turmoil.

A standard trip to the space station carries a price tag of $35-45 million. For an extra $10 million you have the chance to be the first private citizen to walk in space.