Dr. Roy L. DeHart, left, and Dr. Rhea Seddon have joined eight other members on the Committee on Aerospace Medicine and the Medicine of Extreme Environments. (photo by Dana Johnson)
To Mars and back in one piece — VUMC scientists explore effects of space travel
A mission to Mars would take about three years from launch to reentry, including 6-12 months of travel each way and a lengthy stay on Mars while the planets reach optimum position for beginning a return flight. (NASA)
A comparison of Earth, left, and Mars. (NASA)
How might a broken bone heal differently in outer space? How do you perform CPR in a weightless environment? In what ways does the body absorb medicines differently during space travel?
Two Vanderbilt University Medical Center physicians, having accepted appointment to a committee that will advise the National Aeronautics and Space Administration on the practice of medicine to support long-duration space travel, are turning their attention to the many medical unknowns posed by a voyage to Mars.
Dr. Roy L. DeHart, professor of Medicine, and Dr. Rhea Seddon, assistant chief medical officer, have joined eight other members on the Committee on Aerospace Medicine and the Medicine of Extreme Environments, a new standing committee convened by the National Academy of Sciences Institute of Medicine under contract with NASA.
Seddon, the sole former astronaut on the committee, flew three space shuttle missions for NASA between 1985 and 1993, including two life sciences research missions.
DeHart, a national authority on occupational medicine, is a former U.S. Air Force researcher, former commander of the USAF School of Aerospace Medicine, and co-editor of the standard textbook on aerospace medicine.
Rounding out the committee are a surgeon, an anesthesiologist, three internal medicine specialists, an orthopedist, a psychologist and a biomedical informatics specialist. The committee will conduct studies and serve as a focal point for work relating to the practice of medicine during space travel.
Mars is NASA’s next virgin destination and the mission to Mars stands as an obvious motive behind the formation of the committee. However, the trip to Mars lacks the political urgency that fueled the original moon shot. DeHart said he doesn’t expect to see a voyage there within the next 20 years.
“Currently there is no one out there trying to beat us to Mars, at least from this planet,” he said.
A Mars mission would take roughly three years from launch to reentry, including 6-12 months of travel each way and a lengthy stay on Mars while the planets reach optimum position for beginning a return flight. The crew for such a hazardous mission would likely include a doctor and other members trained to provide advanced first aid.
“We’re in no position right now to say that a person can safely make a trip of that duration,” DeHart said
Where no one has gone before
Seddon and DeHart can rattle off lists of crucial unanswered questions regarding medical care and long-duration space travel. What are the effects of long-term exposure to solar radiation? Bone loss from spending three years in low-gravity conditions may be so severe that the reentry maneuver would entail a fractured back, but no one knows for sure. What would be the effect on performance from long-term use of the drugs astronauts rely on to assist regular sleep during space travel? For trips of long duration, would it be a good idea to enforce pre-flight prophylactic removal of the appendix? (A Mir space station crew was nearly forced to make an unscheduled return because of a suspected case of appendicitis; it turned out to be a kidney stone.)
The committee will also need to study behavioral health issues and the dynamics of personal interaction posed by long-duration space travel. Personality clashes flared on the international space station. Competition for attention and affection would develop among any Mars crew that combined men and women.
Rumors about health problems experienced by astronauts on past missions have prompted additional questions on the part of the committee. From the beginning of the space program astronauts have been loath to reveal personal medical information. They’ve learned to guard this information to maintain their flight status and protect their careers. When they experience symptoms of sickness during a mission they generally attempt to keep it to themselves.
For an astronaut, “Any positive medical test could jeopardize your career,” Seddon said. “If there’s something really wrong with you, you need to know it and the flight surgeon needs to know it, but sometimes astronauts are taken off flight status for puzzling findings whose impact is unknown. So naturally, they've become reticent to participate in studies or self-report symptoms." This culture of silence poses a major obstacle for the work of the committee.
Another problem the committee will be grappling with is that, when it comes to enrolling astronauts as study subjects, the pool of subjects is so small that the public may be able to connect an unidentified subject’s medical data to a given astronaut.
“Do we insist that all astronauts come forward with this information?” DeHart said. “Is it legal to require them to sign a contract to be forthcoming, or is that undue pressure? Central ethical questions for the committee include whether all astronauts should be required to become experimental subjects, and how can we use data that involves human exposure without compromising personal information.”
Biomedical data gathered from past missions isn’t organized and much of it isn’t public. To begin answering the many unknowns of long-duration space travel, the committee will seek to gather all available historical data, and it will sponsor further studies, including studies in connection with long-duration space station missions. DeHart also predicts that a voyage to Mars will entail first spending more time on the moon.