Hoping to cash in on a growing appetite for adventure, a start-up company in America's southwest has unveiled plans for a balloon ride to the stratosphere.
It would offer passengers about two hours of space-like views from 30 kilometres above the earth.
Privately owned World View, an offshoot of Paragon Space Development, plans to start selling tickets at US$75,000 per person within a few months, said its president, Jane Poynter.
The company expects to begin flight tests of a demonstration vehicle this year in Arizona and could be flying passengers within three years, she said.
Initially, six passengers and two pilots would be aboard a pressurised capsule now under development. The Federal Aviation Administration has determined it must meet the same safety requirements as a manned spacecraft orbiting earth.
"At Paragon's intended altitude, water and blood boil, and an unprotected person would rapidly experience fatal decompression," the FAA, which oversees commercial space flight in the US, wrote in a letter. The FAA took no position as to whether an altitude of 30 kilometres constitutes outer space, but that Paragon's capsule will need to be capable of operating in space.
By comparison, rides aboard SpaceShipTwo - a suborbital, six-passenger, two-pilot vehicle owned by Virgin Galactic, an offshoot of Richard Branson's Virgin Group - is expected to reach about 110 kilometres.
At that altitude, passengers will experience a few minutes of weightlessness in addition to seeing the curvature of the earth set against the black sky of space.
World View capsules would be propelled by a 1.1 million cubic metre helium balloon and a steerable parafoil, an inflatable, wing-shaped parachute. They should take about 90 minutes to two hours to reach peak altitude, more than twice as high as where commercial jets fly.
While the view may not be as expansive as that offered by SpaceShipTwo, it will last longer. Project developers expect the capsule to linger in the middle of the stratosphere for about two hours before returning to the ground. The descent should take 25 to 40 minutes.
A World View ride would cost less than one-third of the US$250,000 it will cost to fly on SpaceShipTwo. So far, about 650 people have signed up for rides on the latter, which is undergoing testing at a facility in Mojave, California.