(ISS). Still, human health radiation models for predicting health risks are currently hampered by large uncertainties based on the lack of appropriate in situ data. At the present time, these models predict that crewed missions beyond LEO would be limited to 3 months or less because of adverse health impacts, either during the mission or during a crewmember’s lifetime. Without the collection of in situ biological data to support the development of appropriate models, as well as the development of new sensors, advanced dosimetry instruments and techniques, solar event prediction models, and radiation mitigating designs, extended human missions to the Moon, Mars, or near-Earth asteroids (NEAs) may be beyond acceptable risk limits for both human health and mission success. An integrated approach is needed to develop systems and materials to monitor radiation in near-real time and protect crewmembers. In order to implement these technologies, existing radiation protection technologies must be upgraded and new technologies deployed as needed so that the radiation environment is well characterized and solar events can be forecast from at least Earth to Mars. Game changers that will help address this technical challenge include decreased transit times through new propulsion systems to lower exposure; new materials for EVA suits, spacecraft, rovers, and habitats; and new ISRU capabilities to build protective habitats in situ.
2. Environmental Control and Life Support Closed Loop Systems: Develop reliable, closed-loop environmental control and life support systems (ECLSS) to enable long-duration human missions beyond low Earth orbit.
ECLSS for missions beyond Earth orbit (for spacesuits, spacecraft, and surface habitats) are critical for safety and mission success. It was a loss of an oxygen tank and subsequently a compromise of a portion of the ECLSS loop (CO2 removal) that nearly cost the Apollo 13 crew their lives. In missions without early return capability or remote safety depots, the ECLSS system must be as close to 100 percent reliable as possible and/or easily repairable with little or no resupply. Because air and liquid systems are sensitive to gravity level, extended testing of systems in reduced gravity may be necessary before they are integrated into exploration spacecraft. Current ISS experience with both U.S. and Russian ECLSS systems shows significant failure rates that would be unacceptable for an extended human exploration mission. In many cases, ISS ECLSS equipment has been launched and implemented without microgravity testing. Even with ISS testing, data on the performance of ECLSS systems in the reduced gravity of the Moon (~1/6 g) and Mars (~3/8 g) is not and will not be available without suitable reduced/variable-gravity test facilities. This will be a major impediment to maturing ECLSS technologies. New propulsion capabilities that reduce mission duration would reduce exposure to failures.
3. Long-Duration Health Effects: Minimize long-duration crew health effects.
The accumulated international experience with long-duration missions indicates that physical and behavioral health effects and adverse events will occur on long-term exploration missions. In some cases, health effects could be life threatening in the absence of effective diagnosis and treatment. Some of these health-related effects and events can be predicted and planned for, but it is highly likely that others cannot. In such a situation, autonomous, flexible, and adaptive technologies and systems will help promote long-duration health and effectively restore it when accident or illness occurs. Areas of interest include adverse effects of reduced gravity (such as bone loss, muscular and cardiovascular deconditioning, and neurovestibular disorders), in-flight surgery capability in reduced gravity, autonomous medical decision support and procedures management, and in-flight medical diagnosis enabled by a new generation of solid state, non-invasive, wireless biomedical sensors and “laboratory on a chip” technologies.
4. Fire Safety: Assure fire safety (detection and suppression) in human-rated vehicles and habitats in reduced gravity.
Current fire safety technologies for 1 g and microgravity environments are well understood and have an excellent history for longevity as will be needed for future human exploration missions beyond LEO. However, the space shuttle experience included two cases where smoldering electrical fires were detected by crew members working in close proximity to the problem and not by electronic sensors. Also, Russia’s Mir space station experienced a fire