Ensuring that astronauts on a three-year mission to Mars remain healthy is a daunting challenge, writes Steve Farrar.
When the first man or woman sets foot on Mars, it will mark a high point in human exploration and technological endeavour. Only when he or she returns safely to Earth will it also be celebrated as a victory for medical science.
A combination of anti-radiation vaccines, muscle-boosting gene therapies, anti-motion sickness training and a host of other innovations could make the difference. More than 250 scientists in universities across the United States, backed by $26.7 million (£18.3 million) a year from US space agency Nasa, are striving to produce advances through the collaborative National Space Biomedical Research Institute (NSBRI).
The much-mooted three-year manned Mars mission is tipped for the next decade. Although some criticise its great cost, Laurence Young, the institute's director and professor of astronautics at the Massachusetts Institute of Technology, believes mankind needs to visit Mars, both for science and to boost the human spirit. But he notes: "There are very serious, life-threatening problems that become apparent when we make long journeys and go outside the protection of the Earth's magnetic field."
Young hopes for radical solutions from a combination of expertise from basic molecular biology to clinical practice. Their brief is understandably broad:
* Space motion sickness has long been recognised as a debilitating, if temporary, threat to astronauts. The complex neural circuits that allow humans to keep balance, stabilise vision and sense their body's orientation are tuned to inputs from the eyes, the inner ears and muscle sensations. Space motion sickness results from shaking up the pattern of those signals. In research to be published in Acta Astronautica, Young and colleagues have devised a way to train people in a rotating, visually stimulating cylinder to defeat the problem. In daily ten-minute sessions, all participants enjoyed a reduction in motion sickness, and one woman was completely freed of its effects after her 12-day repeat tests.
* Muscle strength wastes away in a weightless environment, and a long-haul astronaut could lose up to a quarter of his muscle mass. NSBRI scientists are developing ways to boost levels through gene therapy, growth hormones, synthetic promoters and novel exercise routines. Their results could also be used to help tackle muscle-wasting diseases and complications suffered by bed-bound patients.
* Outside the Earth's protective magnetic field, an astronaut is at the mercy of a spectrum of radiation from the Sun and intergalactic cosmic radiation. Young said that the Apollo astronauts were lucky not to encounter the potentially fatal danger on their trips to the moon, but long-haul Mars mariners run a far higher risk of tissue damage and genetic mutations that can lead to cancer, central nervous system injuries and other conditions. The scientists are studying radiation's impact on biological systems and how pharmaceuticals such as the breast-cancer drug Tamoxifen might be adapted to lower the risk.
In addition, NSBRI teams are studying ways to boost the immune system and fight infection from dormant viruses; combat the loss of bone structure with drugs called ibandronates; prevent heart function changes that threaten astronauts on their return to Earth; and methods to maintain performance despite sleep loss and turmoil in the biological clock.
They are also working on smart medical systems that combine new body scanning techniques and advanced data storage-and-retrieval systems to enable basic medical practitioners to attempt complex procedures. This might be crucial, as Young says the probability that at least one of a six or eight-strong crew will suffer a serious health problem is high.
Time is short. The therapies will require full clinical testing, and Young wants the research to start bearing fruit within five years. Success could not only see treatments for jet lag and osteoporosis join non-stick frying pans on the list of space research spin-offs. It could stretch the frontiers of human achievement.