Discussions with NASA life sciences and FAA aeromedical personnel provide some initial guidelines for medical issues that should be resolved either prior to, or as part of the process of, developing a service industry based on providing space transportation to the general public.
Space-related medical issues can be placed into two broad categories: short-duration and long-duration. After the initial flights in the early sixties demonstrated that there are no immediate life-threatening effects of space flight, NASA's life-science research has, for the most part, appropriately focused on the problems of longer-duration flights, as would be experienced on a trip to another planet or a tour of duty on a space station. Humans exposed to such longer-duration flights (assuming no artificial gravity) will start to suffer from osteopathic (bone) degeneration, and deconditioning of the cardiovascular system. They will also be exposed to unhealthy amounts of radiation, if the shielding is inadequate. Absent revolutionary breakthroughs in medical technology, these effects can be long lasting, and in some cases (particularly with radiation), permanent.
At least in the near term, however, space tourist experiences, like most tourist experiences, will be of short duration (two weeks or less), and will not be affected by these more debilitating aspects. Of course, staff at orbital hotels, who may have tours of duty of weeks or months, will be affected in the same way as NASA researchers at scientific space platforms, if the hotels are not spun for artificial gravity.
Short-duration trips can again be bifurcated into brief exposures (suborbital or a few orbits), and longer ones (days).
Brief exposures will nominally have only health risks that would arise from any short-duration variable-gravity ride (e.g., intense roller coasters, or trips in high-performance jet aircraft, such as offered by Incredible Adventures). These will include (depending on the magnitude, direction, and duration of a given acceleration) possible blackout, or redout (rush of blood to the head, as opposed to away from it), headache, and nausea. Assuming that the passenger is in reasonably good health, accelerations remain within certain limits, and particularly if the participant is wearing a standard g-suit, such effects will be only transient, and not have any long-term health implications. If a suborbital vehicle is reasonably designed, a precedent for this has been provided by the Incredible Adventures offerings of high-performance jet rides in Russia.
Conventional motion-sickness medications/prophylactics, such as epidermal scopolamine/dexedrine ("scopedex") skin patches, or even over-the-counter medications such as dramamine, may prove sufficiently palliative for this condition. Alternatively, techniques such as autogenic feedback, developed at NASA's Ames Research Center, may be useful for both this and the longer-term effects described below.
It should also be considered that, even if unmitigated, these consequences will at most reduce the market for such experience; there are still many who ride roller coasters and pay thousands of dollars to ride in Mig-29's even with the risk of such illness. Many who have experienced weightlessness in NASA's "Vomit Comet" and private alternatives have expressed interest in repeating the experience—even those who got quite ill. One of the values of such early experiences, even if no new medical insights are gained, will be to get a better understanding of the market even in the presence of possible unpleasant side effects.
During longer exposures to weightlessness, of days or weeks, the "Space Adaptation Syndrome," more commonly known as space sickness, will appear in (if NASA experience is any guide) about half of the participants. This is akin to seasickness, in which the passenger may feel a malaise, and be nauseous, with difficulty in keeping food down.
In general, it is important to note that the space tourism business will have a much more potent remedial arsenal with which to tackle any space-sickness problems than does NASA, for the simple reason that space passengers, and particularly pleasure-seeking tourists, will not be operating under the same requirements of job performance that are typically expected, if not required, from astronauts. This opens up pharmaceutical/therapeutic possibilities not available to NASA personnel, who must reliably perform critical tasks on specific schedules.