Aerospace medicine gearing up for tourists in space
■ Physicians anticipate some civilian space travelers will have chronic medical issues.
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A commercial space flight industry is working to make the adventure and romance of space travel available to the general public -- or at least to those with $200,000 or more to spare.
Space tourism, still in its embryonic stages, has some experts estimating that 10,000 to 15,000 people a year will fly in orbital and suborbital space in the next decade.
For aerospace medicine physicians, this will mean preparing a less physically fit passenger for the demands of space. Instead of 20-year-old fighter pilots in peak condition, space tourists could be 18 to 80 years old with medical conditions that might complicate space travel but not automatically disqualify them.
"We're bringing civilian space travel into a different medical paradigm," said Jan Stepanek, MD, MPH, director of the aerospace medicine program at Mayo Clinic in Arizona and a physician within Mayo's executive health program. "Are these people going to have problems with coronary artery disease or pulmonary disease that could put them at risk? Something that could lead to an in-flight medical emergency that could compromise the safety of passengers or the safety of the flight?"
These are the questions he is asking as he anticipates the challenges ahead. If there is a typical space tourist, that client might mirror the men and women in Mayo's executive health program, Dr. Stepanek speculated. There, 75% of clients are male, and 55 is the average age. They also tend to be successful businessmen and -women with hard-driving personalities and corresponding health problems, such as hypertension and coronary disease.
This is why Mayo Clinic in Arizona has joined aerospace experts at the University of Texas Medical Branch in Galveston and Wyle Laboratories in Houston to form a medical space tourism program. The trio is offering commercial space flight companies their services to screen and prepare civilians for trips into orbital and suborbital space.
The program has yet to sign its first client, but when it does, Dr. Stepanek anticipates that the space tourist likely will be heading off for a suborbital trip, which lasts two to three hours, including a 30-minute rocket ride into space. At least two commercial space flight companies, Virgin Galactic and Rocketplane, anticipate inaugural suborbital flights before the end of 2008. Another commercial space company, Space Adventures, has sent four clients into orbit. For $25 million each, its customers stay at the International Space Station for 10 days.
Physically preparing tourists
Space tourism may sound futuristic, but civilian space flight is real enough that the Federal Aviation Administration has issued guidelines.
It has not, however, set specific medical standards for passengers, said James Vanderploeg, MD, MPH, visiting associate professor of clinical preventive medicine at UTMB and chief medical officer for Virgin Galactic. He is screening more than 100 people who have paid $200,000 each for future suborbital flights.
Creating specific medical standards is one of his tasks for Virgin Galactic. But his work is complicated by the lack of scientific data on how g-forces affect the average person.
Nevertheless, aerospace health experts say the initial patient screening steps will be simple. Clients will see their personal physicians for a physical and have the results sent to their carrier's aerospace physician.
If they are flying Virgin Galactic, Dr. Vanderploeg will read their records and flag worrisome ones.
To better evaluate how potential passengers with health concerns such as hypertension, diabetes or obstructive pulmonary disease will handle g-force stress or atmosphere changes, Dr. Vanderploeg plans to ask them to undergo a centrifuge ride or altitude chamber session.
The centrifuge duplicates launch and re-entry, where gravity may build to six times a person's body weight. Under this stress, passengers can practice breathing and do other exercises to help them handle the demands on their bodies, he said.
For example, during acceleration, the blood drains from the head toward the toes. If individuals are not prepared to counteract this, tunnel vision develops and the person may pass out. During re-entry, the g-forces create chest-to-back pressure, pushing more blood into the head, sharply increasing blood pressure in the brain and increasing stroke risk for those with hypertension.
Cabin pressure is expected to be the same as on a commercial flight, eliminating the need for pressure suits, Dr. Vanderploeg said. But the typical cabin will be snug.
"If you don't like being inside a little airplane, you won't like being in a small spaceship," he said. "When that rocket engine lights, you are going somewhere in a big hurry, which can be very frightening."
Dr. Vanderploeg said it eventually may be possible to include people with physical disabilities.
Stephen Hawking, PhD, the well-known physicist who has amyotrophic lateral sclerosis, successfully participated in a parabolic flight, which creates moments of weightlessness.