The latest flight test for Virgin Galactic's SpaceShipTwo saw it hurtling out of control and towards the ground at a startling speed, according to reports.
The spacecraft is the prototype that will take space tourists on suborbital flights from the new Spaceport America, which Sir Richard Branson officially opened today.
It was joined on its 16th glide flight by two pilots and a flight test engineer, lifted to a high altitude by its carrier plane, WhiteKnightTwo.
But, when WhiteKnightTwo released it, the spacecraft began hurtling out of control.
One observer told space.com: 'It dropped like a rock and went straight down
'Typically, it takes 11 minutes to land, but this time it was only seven minutes before they were on the ground. It was a nail-biter ... but that's how you learn.'
The fast-acting crew switched on the ship's safety back-up, the feather re-entry system, which enabled the spacecraft to land safely by using aerodynamics to control speed and altitude.
But George Whitesides, Virgin Galactic's CEO and president, wasn't worried, telling the Daily Mail: 'Yes, apparently the tails exhibited stall characteristics in the test - which was a steep nose down manoeuvre.
The news came as Sir Richard celebrated the launch of the new $209 million Spaceport America in New Mexico.
Around 450 people - including comedian Russell Brand - have signed up to for space flight tickets, and around 150 of them attended the ceremony, where guests were treated to a flyover by WhiteKnightTwo - the mothership that will help take space tourists on suborbital flights on the SpaceShipTwo.