While SpaceShipTwo builder Scaled Composites prepares the commercial spaceship for its first rocket-powered test flight, owner Virgin Galactic has been thinking about all the armchair astronauts lining up to finally test their space legs.
Their fliers won't go far -- just 65 miles or so above the southern New Mexico launch site -- and they won't be gone long. The supersonic sprint beyond the atmosphere will last only a few minutes.
But Virgin Galactic is betting that the ride, albeit short, is sweet enough to warrant its $200,000 fare. As of last week, 545 people had put down deposits or paid the full fee to find out for themselves.
So what will the experience be like? Here's a perspective from SpaceShipTwo lead pilot David Mackay.
After a three-day training program, passengers will leave Virgin's terminal at the newly built Spaceport America, located near Las Cruces, NM, and climb aboard SpaceShipTwo, which they'll find hanging beneath the twin-boomed White Knight carrier aircraft. The six-passenger, two-pilot vehicle is based on the prize-winning SpaceShipOne prototype, which now hangs in the Smithsonian Institution's Air & Space Museum.
Unlike the rocket ride to space, which will come after SpaceShipTwo is released, White Knight's flight up to about 50,000 feet will be long and slow.
"It's a low-key part of the experience, but I think it will be quite interesting," Mackay said at the International Symposium for Personal and Commercial Spaceflight last week.
"It's probably a little bit like a roller coaster ride where you're all excited just to strap in and then you have this long, steep climb, up to that initial drop. Some people love that sort of thing. Others perhaps get a little bit nervous. We have to think about that -- how to make everyone relaxed and keep them calm during that part of the flight," he said.
Upon reaching the launch altitude, there will be short countdown while the pilots and flight controllers run through a checklist before SpaceShipTwo is released.
"When you're dropped from underneath White Knight, you do feel briefly like you're falling. That's quite a nice feeling," Mackay said.
"Very soon after, we light the rocket motor and it all starts to get really damn exciting," he said.
Passengers will feel about 3.5 times the force of Earth's gravity for just over a minute, and another three to 3.5 push when the pilots turn the spaceship from horizontal to vertical.
"It's quite an abrupt turn," Mackay said.
The rocket engine will be shut down at about 150,000 feet, close to the edge of the atmosphere. SpaceShipTwo will keep climbing until it reaches about 350,000 feet or so.
"By the time we're passing 200,000 feet there's virtually no measurable aerodynamic loads on the vehicle. At that point we're going to allow the passengers to unstrap and experience this fantastic sensation of zero-g and float to the windows," Mackay said.
Pilots will probably flip the ship over so passengers have a view of the Earth from the roof-top windows.
"The best view is probably of the Earth rushing away from you, which is quite exciting," Mackay said.
The apex of the ride will be between 62 miles and 68 miles above the planet, and then it's all downhill.
"Before we meet the atmosphere, we orient the vehicle back around to the entry position. It's got this very clever, unique ‘feather' system which will ensure that we always enter the atmosphere in the optimal attitude. It's a very, very stable attitude, a hands-free task for the pilots," Mackay said.
Gravity forces will build back slowly at first and then accelerate, peaking at about 5.5 to six times the force of Earth's gravity and then drop off. For the ride home, passengers' seats will recline, which should make the forces easier to handle.
Surprisingly, the flight back to Earth is expected to be just as noisy as the rocket ride up, as air blasts the bottom of the vehicle during its supersonic descent through the atmosphere.
SpaceShipTwo will decrease in speed and go subsonsonic (slower than the speed of sound) by about 70,000 feet. The spaceship's tail section, positioned forward for re-entry, will be moved back for the glide back to the runway.
For now, Virgin Galactic isn't planning to put its passengers in pressurized flight suits.
"It's a complication to the experience," Mackay said. "A lot of people actually find them quite claustrophobic, and they tend to get very warm. We think our system is both sufficient in redundancy and safety."
That's not to say passengers will fly in shorts and T-shirts.
"Our customers will probably wear some from of coverall -- no doubt it'll be very trendy and very Virgin -- and possibly some type of protective headgear," Mackay said.
"They'll look the part," he added. "I think a lot of people actually do want to look like an astronaut when they go into space."
SpaceShipTwo's powered test flights are expected to begin before the end of the year. Spaceport America is preparing for the spaceship's first commercial flight in December 2013.