By Dr David Whitehouse
BBC News Online science editor
The first private manned spacecraft will be launched into space on 21 June carrying an as yet unnamed astronaut.
SpaceShipOne could make aviation history
SpaceShipOne is built by aviation pioneer Burt Rutan who hopes to win the Ansari X-prize of $10m (£5.7m) for the first non-government flight into space.
The craft, sponsored by Microsoft's co-founder Paul Allen, has to reach an altitude of 100km (329,000ft) twice in two weeks to win the coveted award.
A total of 25 other teams across the world are competing for the prize.
But the SpaceShipOne testing programme shows the Californian design is clearly in the lead.
"Every time SpaceShipOne flies, we demonstrate that relatively modest amounts of private funding can significantly increase the boundaries of commercial space technology," Allen said in a statement.
In an impressive demonstration over Mojave airport last month, SpaceShipOne and its carrier aircraft White Knight moved a step closer to claiming the X-prize when pilot Mike Melvill took the vehicle nearer to space than any non-governmental manned craft has been before.
SPACE FLIGHT ATTEMPT
SpaceShipOne boosts itself into the atmosphere
It aims for an altitude of 100km (62 miles)
Wings fold up to provide "feather" effect
Converts back to non-feathered glider
Its 64km (211,000ft) altitude was twice as high as SpaceShipOne had been piloted to before.
To win the Ansari X-Prize, 100km (329,000ft) - the official boundary of space - has to be reached twice in two-weeks by a three-person spacecraft.
SpaceShipOne's 14 shakedown tests have now put it into a position to make the bid for space.
On 21 June, SpaceShipOne will glide free of White Knight and then fire its rockets, accelerating to Mach 3 - three times the speed of sound - in a climb that should take it to about 100km. This will be high enough to escape Earth's atmosphere but not to maintain an orbit.
If all goes well, an attempt will be made on the X-Prize.
Burt Rutan's company Scaled Composites became the first non-governmental body to be granted a licence for a space launch when the US Federal Aviation Administration gave it one on 1 April.
The X-prize will mark a new era in manned spaceflight when private companies are able to make short sub-orbital hops for paying customers.
It is hoped that a market for space tourism can be developed.
"Since Yuri Gagarin and Al Shepard¿s epic flights in 1961, all space missions have been flown only under large, expensive government efforts," said Burt Rutan.
"By contrast, our programme involves a few, dedicated individuals who are focused entirely on making spaceflight affordable.
"Without the entrepreneur approach, space access would continue to be out of reach for ordinary citizens. The SpaceShipOne flights will change all that and encourage others to usher in a new, low-cost era in space travel."