A three-man crew from Italy soared more than 80 km above the New Mexico desert on Thursday (local time) aboard a Virgin Galactic rocket plane.

It was  the company’s first flight of paying customers to the edge of space since British billionaire Richard Branson founded the venture in 2004.

Seats cost between $US250,000 ($377,728) and $US450,000 ($679,910), and Virgin Galactic said it has already booked a backlog of some 800 customers.

The two Italian air force officers and an aerospace engineer from the National Research Council of Italy made the brief suborbital ride with three Virgin Galactic crew members, two of whom piloted the vehicle, VSS Unity, once it was launched at high altitude from the belly of its twin-fuselage carrier plane.

The flight marked a long-delayed breakthrough for Virgin Galactic Holding Inc, finally inaugurating commercial service after nearly 20 years fraught by development setbacks.

Mr Branson founded the company with renowned aerospace mogul Burt Rutan in a venture that grew out of the 2004 Ansari X Prize competition won by Rutan’s experimental spaceplane — forerunner of the SpaceShipTwo design of Unity.

Virgin becomes the latest commercial enterprise, along with Jeff Bezos’s Blue Origin and fellow billionaire Elon Musk’s SpaceX, catering to wealthy customers willing to pay large sums of money to experience the exhilaration of supersonic rocket speed, microgravity and the spectacle of the Earth’s curvature from space.

The Galactic 01 mission of the Italian team, however, was billed as a scientific one, with the three men planning to collect biometric data, measure cognitive performance and record how certain liquids and solids mix in microgravity conditions.

For Italian Air Force Colonel Walter Villadei the flight was also part of his astronaut training for a future mission to the International Space Station.

The gleaming white rocket plane was borne aloft at around 10.30am local time attached to the underside of its transport jet, VMS Eve, as the carrier plane took off from Spaceport America near the New Mexico town of Truth or Consequences.

Reaching its launch-altitude point roughly 13.5 km above the ground, Unity was then released from the mothership and fell away as the pilots ignited the vehicle’s engine to send the rocket plane streaking in a near-vertical climb at about three times the speed of sound to the blackness of space.

Virgin Galactic said Unity topped out its flight at an altitude of nearly 85.1 km.

At the apex of the flight, with the rocket shut down, the crew then experienced a few minutes of weightlessness before the craft shifted into re-entry mode and began its gliding descent back to Earth.

A Virgin Galactic webcast showed live footage of crew members strapped into their seats in flight suits and sunglasses as they neared the height of their voyage, then enjoying the thrill of microgravity as Villadei unveiled an Italian flag in the cabin.

The company had said before Thursday’s launch that a successful flight would pave the way for Unity to fly again in early August, with monthly flights thereafter.