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