Virgin Galactic, the commercial space endeavour led by billionaire Richard Branson, has been rejected by an Australian astronaut as "dangerous" to human space flight.
Spaceman Andy Thomas told reporters in Adelaide last night that while he supported what Branson was contributing to satellite technology, he was critical of his goals to take tourists into orbit.
"Its true that he will fly to the edge of space, but he cant stay there. He falls right back down," said Thomas, according to news agency Australian Associated Press.
"Its really just a high-altitude aeroplane flight and a dangerous one at that. As a technology to get humans out into space its a go nowhere, dead-end technology."
Virgin Galactic successfully reached the edge of the world's atmosphere for the first time in its fourth test flight last week.
The Spaceship Two rocket, which was carried up to a height of above 12,000 metres by a specially-designed plane before igniting its motors, reached 82.7km above the ground. The rocket motor burnt for 60 seconds and the aircraft travelled at 2.9 times the speed of sound.
More than 600 people have bought tickets to be on the first round of commercial space flights in six-passenger rockets by Virgin, spending up to $250,000 (£200,000) a ticket.
Thomas was a previous participant of the Nasa space programme, having travelled into space four times and carried out stints at both the Mir and International Space Station.
A spokesperson for Virgin Galactic has been contacted for comment.