About Those Space Joyrides…

With the age of suborbital tourism beckoning, hundreds of wealthy people have signed up to take rides to the edge of space, a trip that will end almost as soon as it begins, but should confer serious bragging rights when the talk turns to summer vacations.

Of course, if just experiencing weightlessness is your goal, you can already do it for far less than Virgin Galactic’s $200,000 ticket price—but only in 30-second bursts. Inside a modified Boeing 727 operated by Zero Gravity Corporation, adventure tourists can spend a few thousand dollars to get a taste of weightlessness and sample lunar and Martian gravity as the airplane flies repeated roller-coaster-like parabolas. During their half-minutes of reduced gravity they can float, tumble, even get married. But there’s no view of Earth, and it’s more like an amusement park ride than a rocket launch.

The suborbital spaceships now on the drawing boards will carry tourists to the edge of space (traditionally set at 100 kilometers, or 62 miles altitude), but not so high or fast that they go into orbit. Virgin Galactic’s SpaceShipTwo will provide up to six minutes of weightlessness, while Armadillo Aerospace, XCOR, and various other companies will make you feel weightless for about three minutes.

Since XCOR’s Lynx spacecraft holds just a pilot and one passenger in a tiny side-by-side cockpit, the company has decided that passengers will remain strapped in for the whole trip—just as Alan Shepard and Gus Grissom did during their 15-minute suborbital missions to test out NASA’s new Mercury spacecraft in 1961.

Other companies have released animations showing passengers unstrapping from their couches, floating around in weightlessness, then returning to their couches before atmospheric reentry.

XCOR thinks that’s a bad idea.

“Unstrapping and re-strapping in such a short time frame would be a risky endeavor,” says the company’s communications representative, Mike Masse. He believes that passengers will be so engrossed by the spectacular view that they won’t mind being confined to their couches.

Virgin Galactic sees less of a problem with its SpaceShipTwo. “Our experience will have significantly slower transitions between zero-G and G than [do the parabolic airplane flights],” says James Vanderploeg, the company’s chief medical officer. “We're confident that our customers will be both ready and eager to get up out of their seats once they reach space.”

Neil Milburn, vice president of program management at Armadillo Aerospace, agrees that the transition should be comparable to parabolic flight. “As soon as there is a modest amount of G-force, one naturally ‘sinks’ back to the bottom.”

But two astronauts who are also physicians say the airplane and suborbital experiences will be markedly different. “G onset on the way back [from 100 km altitude] will be quite brisk, and the Gs will be in excess of six on some vehicles,” says Scott Parazynski, a veteran of five NASA spaceflights. “My guess is the last 30 to 45 seconds of the microgravity phase will have to be allocated to seat ingress.”

Dave Williams, a retired Canadian astronaut who flew twice on the shuttle, is even more cautious. “Depending upon their focus, and how congested the cabin is with floating passengers, I would guess it could take one to two minutes for a passenger to return to their couch and strap in.”

Both astronauts note that the time needed for seat ingress will vary according to each vehicle’s strapping procedures. In Armadillo’s case, reseating will be quick, lasting 10 to 20 seconds at most, according to Milburn, who adds that, “Audible and visual cues will signal that weightlessness is about to end, and of course, training will be provided prior to flight.”

While this still leaves plenty of time for somersaults, suborbital tourist companies may want to warn their passengers about the possibility of nausea and vomiting. Motion sickness is common on zero-G airplane flights, particularly after multiple parabolas. But Vanderploeg says the ride on SpaceShipTwo will be more like flying a single parabola, and nausea on the first parabola is extremely rare. He says decisions about using motion sickness medication on Virgin Galactic flights will be made “on a case-by-case basis with each passenger.”

Although symptoms of space motion sickness typically don’t appear during the first 30 seconds of weightlessness, astronauts often feel them in the first few minutes after reaching space, which makes it a concern for suborbital tourists. Anti-motion sickness drugs might not be enough. Astronauts typically try to minimize head movements and stay still during their first moments in space. Tourists may want to plan their moves carefully, or just accept that once-in-a-lifetime acrobatics are worth a little vomiting.

Even then, getting sick in a spacesuit has its own risks. XCOR and Armadillo passengers will wear suits that can pressurize if needed. Since vomiting is possible even without acrobatics, XCOR passengers will fly with their helmet visors open. Armadillo is working on a system that would close the visors automatically, while Virgin Galactic’s decision on requiring spacesuits awaits the results of future test flights.

However they address the risk, space tourism companies will make sure that none of their passengers vomit inside a closed helmet—which would quickly turn an unpleasant mess into a danger.

As for the spaceship pilots, they will be highly trained and experienced. But they’ll be flying in a regime that only four people—Shepard, Grissom, and SpaceShipOne pilots Mike Melvill and Brian Binnie—have experienced before. As aerospace medical researchers Mark Campbell and Alejandro Garbino noted in a recent journal article, “Only further suborbital spaceflight experience will clarify if pilot performance will be affected.”

David Warmflash, M.D., is an astrobiologist, science journalist, and science lead for the U.S. team of the Planetary Society's Phobos Living Interplanetary Flight Experiment. Follow him on Twitter @CosmicEvolution