Richard Branson ready for space launch aboard Virgin Galactic rocket plane

British billionaire Richard Branson was due on Sunday to climb into his Virgin Galactic passenger rocket plane and soar more than 50 miles above the New Mexico desert in the vehicle's first fully crewed test flight to the edge of space.

Branson, one of six Virgin Galactic Holding Inc employees strapping in for the ride, has touted the flight as a precursor to a new era of space tourism, with the company he founded poised to begin commercial operations next year.

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A discount travel service it is not. But demand is apparently strong, with several hundred wealthy would-be citizen astronauts already having booked reservations, priced at around $250,000 per ticket.

The Swiss-based investment bank UBS has estimated the potential value of the space tourism market reaching $3 billion annually by 2030.

Proving rocket travel safe for the general public is key, given the inherent dangers of spaceflight.

An earlier prototype of the Virgin Galactic rocket plane crashed during a test flight over California's Mojave Desert in 2014, killing one pilot and seriously injuring another.

Branson's participation in Sunday's flight, announced just over a week ago, is in keeping with his persona as the daredevil executive whose Virgin brands - from airlines to music companies - have long been associated with ocean-crossing exploits in sailboats and hot-air balloons.

His ride-along also upstages rival astro-tourism venture Blue Origin and its founder, Amazon mogul Jeff Bezos, in what has been popularized as the "billionaire space race." Bezos has been planning to fly aboard his own suborbital rocketship, the New Shepard, later this month.

Branson, a week away from his 71st birthday, has insisted he and Bezos are friendly rivals and not engaged in a personal contest to beat one another into space.

A third player, fellow billionaire proprietor Elon Musk's SpaceX, plans to send its first all-civilian crew (without Musk) into orbit in September, after having already launched numerous cargo payloads and astronauts to the International Space Station for NASA.

The launch of Virgin Galactic's VSS Unity rocket plane on Sunday will mark the company's 22nd test flight of its SpaceShipTwo system, and its fourth crewed mission beyond Earth's atmosphere. But it will be the first to carry a full compliment of space travelers - two pilots and four "mission specialists," Branson among them.

Weather permitting, the gleaming white spaceplane will take off at around 0900 ET (1300 GMT) on Sunday attached to the underside of the twin-fuselage carrier jet VMS Eve - named for Branson's mother - from Spaceport America near the aptly named New Mexico town of Truth or Consequences. Virgin Galactic occupies a large section of that facility, about 75 miles (120 km) north of Las Cruces.

Separating from the carrier jet at an altitude of 50,000 feet, Unity's pilots will ignite its rocket engine to send the spaceplane streaking in a near-vertical climb to the blackness of space some 55 miles high, where the crew will experience about 4 minutes of microgravity.

The vehicle's engine will then be shut down, and the craft will be shifted into re-entry mode and make a gliding descent to a runway at the spaceport. The entire flight, from takeoff to landing, should take about 90 minutes.

Branson's official role is to "evaluate the private astronaut experience," and his observations will be used to "enhance the journey for all future astronaut customers," according to Virgin's press materials.

The spaceplane's two pilots, Dave Mackay and Michael Masucci, will control the ignition and shutoff of the ship's rocket engine, and activate the vehicle's "feathered" tail maneuver for re-entry.

The three other mission specialists are Beth Moses, the company's chief astronaut instructor; Virgin Galactic's lead operations engineer Colin Bennett; and Sirisha Bandla, a research operations and government affairs vice president.

Assuming the mission goes well, Virgin has plans for two further test flights of the spaceplane before beginning commercial service in 2022.