Health care for deep space explorers.

[Formula: see text]There is a growing desire amongst space-faring nations to venture beyond the Van Allen radiation belts to a variety of intriguing locations in our inner solar system. Mars is the ultimate destination. In two decades, we hope to vicariously share in the adventure of an intrepid crew of international astronauts on the first voyage to the red planet.This will be a daunting mission with an operational profile unlike anything astronauts have flown before. A flight to Mars will be a 50-million-kilometre journey. Interplanetary distances are so great that voice and data communications between mission control on Earth and a base on Mars will feature latencies up to 20 min. Consequently, the ground support team will not have real-time control of the systems aboard the transit spacecraft nor the surface habitat. As cargo resupply from Earth will be impossible, the onboard inventory of equipment and supplies must be planned strategically in advance. Furthermore, the size, amount, and function of onboard equipment will be constrained by limited volume, mass, and power allowances.With less oversight from the ground, all vehicle systems will need to be reliable and robust. They must function autonomously. Astronauts will rely on their own abilities and onboard resources to deal with urgent situations that will inevitably arise.The deep space environment is hazardous. Zero- and reduced-gravity effects will trigger deconditioning of the cardiovascular, musculoskeletal, and other physiological systems. While living for 2.5 years in extreme isolation, Mars crews will experience psychological stressors such as loss of privacy, reduced comforts of living, and distant relationships with family members and friends.Beyond Earth's protective magnetosphere, the fluence of ionising radiation will be higher. Longer exposure of astronauts to galactic cosmic radiation could result in the formation of cataracts, impaired wound healing, and degenerative tissue diseases. Genetic mutations and the onset of cancer later in life are also possible. Acute radiation sickness and even death could ensue from a large and unpredictable solar particle event.There are many technological barriers that prevent us from carrying out a mission to Mars today. Before launching the first crew, we will need to develop processes for in-situ resource utilisation. Rather than bringing along large quantities of oxygen, water, and propellant from Earth, future astronauts will need to produce some of these consumables from local space-based resources.Ion propulsion systems will be needed to reduce travel times to interplanetary destinations, and we will need systems to land larger payloads (up to 40 tonnes of equipment and supplies for a human mission) on planetary surfaces. These and other innovations will be needed before humans venture into deep space.However, it is the delivery of health care that is regarded as one of the most important obstacles to be overcome. Physicians, biomedical engineers, human factors specialists, and radiation experts are re-thinking operational concepts of health care, crew performance, and life support. Traditional oversight of astronaut health by ground-based medical teams will no longer be possible, particularly in urgent situations. Aborting a deep space mission to medically evacuate an ill or injured crew member to Earth will not be an option. Future crews must have all of the capability and responsibility to monitor and manage their own health. Onboard medical resources must include imaging, surgery, and emergency care, as well as laboratory analysis of blood, urine, and other biospecimens.At least one member of the crew should be a broadly trained physician with experience in remote medicine. She/he will be supported by an onboard health informatics network that is artificial intelligence enabled to assist with monitoring, diagnosis, and treatment. In other words, health care in deep space will become more autonomous, intelligent, and point of care.The International Commission on Radiological Protection (ICRP) has dedicated a day of its 5th International Symposium in Adelaide to the theme of Mars exploration. ICRP has brought global experts together today to consider the pressing issues of radiation protection. There are many issues to be addressed: Can the radiation countermeasures currently used in low Earth orbit be adapted for deep space?Can materials of low atomic weight be integrated into the structure of deep space vehicles to shield the crew?In the event of a major solar particle event, could a safe haven shelter the crew adequately from high doses of radiation?Could Martian regolith be used as shielding material for subterranean habitats?Will shielding alone be sufficient to minimise exposure, or will biological and pharmacological countermeasures also be needed?Beyond this symposium, I will value the continued involvement of ICRP in space exploration. ICRP has recently established Task Group 115 to examine radiation effects on the health of astronaut crew and to recommend exposure limits. This work will be vital. Biological effects of radiation could not only impact the health, well-being, and performance of future explorers, but also the length and quality of their lives.While humanity has dreamed of travel to the red planet for decades, an actual mission is finally starting to feel like a possibility. How exciting! I thank ICRP for its ongoing work to protect radiation workers on Earth. In the future, we will depend on counsel from ICRP to protect extraterrestrial workers and to enable the exploration of deep space.

Measurements of the neutron dose and energy spectrum on the International Space Station during expeditions ISS-16 to ISS-21.

As part of the international Matroshka-R and Radi-N experiments, bubble detectors have been used on board the ISS in order to characterise the neutron dose and the energy spectrum of neutrons. Experiments using bubble dosemeters inside a tissue-equivalent phantom were performed during the ISS-16, ISS-18 and ISS-19 expeditions. During the ISS-20 and ISS-21 missions, the bubble dosemeters were supplemented by a bubble-detector spectrometer, a set of six detectors that was used to determine the neutron energy spectrum at various locations inside the ISS. The temperature-compensated spectrometer set used is the first to be developed specifically for space applications and its development is described in this paper. Results of the dose measurements indicate that the dose received at two different depths inside the phantom is not significantly different, suggesting that bubble detectors worn by a person provide an accurate reading of the dose received inside the body. The energy spectra measured using the spectrometer are in good agreement with previous measurements and do not show a strong dependence on the precise location inside the station. To aid the understanding of the bubble-detector response to charged particles in the space environment, calculations have been performed using a Monte-Carlo code, together with data collected on the ISS. These calculations indicate that charged particles contribute <2% to the bubble count on the ISS, and can therefore be considered as negligible for bubble-detector measurements in space.

Canadian medical experiments on Shuttle flight 41-G.

During the 41-G mission, two payload specialist astronauts took part in six Canadian medical experiments designed to measure how the human nervous system adapts to weightlessness, and how this might contribute to space motion sickness. Similar tests conducted pre-flight provided base-line data, and post-flight experiments examined re-adaptation to the ground. No changes were detected in the vestibulo-ocular reflex during this 8-day mission. Pronounced proprioceptive illusions were experienced, especially immediately post-flight. Tactile acuity was normal in the fingers and toes, but the ability to judge limb position was degraded. Estimates of the locations of familiar targets were grossly distorted in the absence of vision. There were no differences in taste thresholds or olfaction. Despite pre-flight tests showing unusual susceptibility to motion sickness, the Canadian payload specialist turned out to be less susceptible than normal on-orbit. Re-adaptation to the normal gravity environment occurred within the first day after landing.

Space travel: bringing medical discoveries down to Earth.

Space travel has necessitated intensive study of certain physical conditions, notably cardiovascular deconditioning, motion sickness, musculoskeletal atrophy and psychological isolation. Benefits of this research are beginning to be available to terrestrial medicine, for example in research on osteoporosis and motion sickness. Other space technology of benefit to medicine includes diagnostic and therapeutic devices, transmission of medical data and satellite communications. A permanently inhabited space station is planned for the 1990s and further research into isolation, occupational hazards in remote locations, transportation of accident victims and stabilization awaiting transportation can be expected, all with probable spinoffs for terrestrial medicine. Space is also a good environment for production of very pure, specific pharmaceuticals, such as alpha1-antitrypsin, interferon and pancreatic beta cells.