In the context of extra-terrestrial missions, the effects of hypogravity (0 < G < 1) on the human body can reduce the well-being of the crew, cause musculoskeletal problems and affect their ability to perform tasks, especially during long-term missions. To date, studies of the effects of hypogravity on human movement are limited to experiments on the lower limbs. Here, we extend the knowledge base to the upper limbs, by conducting experiments to evaluate the effect of hypogravity on upper limb physical fatigue and mental workload in participants. Our hypothesis was that hypogravity would both increase participant productivity, by reducing overall physical fatigue expressed in Endurance Time, and reduce mental workload. Task Intensity-Endurance time curves are developed especially in seated positions, while performing static, dynamic, repetitive tasks. This experiment involved 32 healthy participants without chronic problems of the musculoskeletal system aged 33.59 ± 8.16 years. Using the collected data, fatigue models were constructed for tasks of varying Intensity. In addition, all participants completed the NASA – Task Load Index subjective mental workload assessment, which revealed the level of subjective workload when executing different tasks. We found two trends in the empirical fatigue models associated with the difference between the strength capabilities of males and females. The first is a significant positive (p = 0.002) relation between Endurance time and gravity level (⅙ G Moon, ⅓ G Mars, 1G) with negative coefficient for males and females for a static task. And there is marginal relation (p < 0.1) between overall mental workload and gravity level with a positive coefficient for males and females for the same task. The same trend was observed for dynamic and repetitive tasks. We concluded that the Task Intensity-Endurance Time model, adapted to hypogravity in combination with subjective mental assessment, is useful to human fatigue investigation. The combination of these methods used for ergonomic analysis and digital human modeling, could improve worker productivity. Finally, this study may help prepare astronauts for long-term missions on the Moon and Mars and improve our understanding of how we can prevent musculoskeletal disorders caused by hazardous manual handling under such extreme environments.
Ice caps have been known ever since they were first observed by Cassini. Robotic exploration missions, starting with Mariner 9, have confirmed that they are composed of water ice. During later missions, instruments such as Mars Global Surveyor's MOLA have established a detailed topography and have estimated their depth at about 3 km in the thickest part, while detailed internal structure has been investigated by MARSIS from Mars Express and SHARAD from the Mars Reconnaissance Orbiter. This analysis proposes to establish a base near North Polar Layered Deposits to investigate Mars' climate, hydrological processes and to test for possible traces of life. The objectives of the mission are to sustain a crew for nine months on the surface of Mars, near the North Pole, and to bring the crew back to Earth safely. During the surface mission, the crew will drill and analyze Polar Layered Deposits in ice samples. Furthermore, because the North Polar region provides an easy access to water ice, this area has the potential of sustaining a long-term human presence. The Mars Polar Research mission shall therefore prepare for long term missions, spanning over multiple crew generations. Indeed, longer duration missions and larger crews should be facilitated by this first mission. This paper describes a mission design for a Mars Polar Research base using systems engineering approach and scenario testing. The goal of the work is to establish a strategy composed of various technologies that have been selected accordingly. The requirements related to crew composition, human physiology and psychology adaptation, quality of communication, challenges and prospects of advancing science, as well as optimum habitat design and its usability, are derived and compiled into mass, volume, data and power consumption. A design for the base and mission scenario is also proposed. Given the identified requirements, possible technologies for life support systems, radiation protection, in-situ propellant production, thermal control, air pressure difference compensation and availability of power are discussed and solutions to focus on are recommended. Furthermore, the requirements for a long-term mission preparation are also identified and solutions to include in a first Mars mission with crew are recommended. In conclusion, approximately 110 metric tons and 160 kW are required to enable a Mars Polar mission with a human crew. A two-phase mission is recommended for enabling the testing of key in-situ resource utilization technologies allowing to minimize mass, while ensuring the security of the crew. The use of optimal payload and fairing, a Mars orbit crane system and deployable structures are recommended. Finally, in preparation for a long-term presence of humans on Mars, including in-situ testing of key technologies enabling the production of consumables facilitating autonomy from Earth is suggested. The consumables that have been identified as not being able to be tested before a first crew is sent to Mars are food and energy production. These dev...
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