Work in Reduced-Gravity Environments

Author(s):  
E. C. Wortz

Research data on human performance in weightless and lunar-gravity environment are considered on a single continuum of reduced traction. Apparent contradictions in the effects of reduced gravity on tasks requiring the use of the upper torso and those requiring locomotion are resolved. It is concluded that reduced traction systematically reduces the efficiency of work in all reduced-gravity conditions.

2020 ◽  
Vol 39 (7) ◽  
pp. 797-811 ◽  
Author(s):  
Parna Niksirat ◽  
Adriana Daca ◽  
Krzysztof Skonieczny

One of the major challenges faced by planetary exploration rovers today is the negotiation of difficult terrain, such as fine granular regolith commonly found on the Moon and Mars. Current testing methods on Earth fail to account for the effect of reduced gravity on the soil itself. This work characterizes the effects of reduced gravity on wheel–soil interactions between an ExoMars rover wheel prototype and a martian soil simulant aboard parabolic flights producing effective martian and lunar gravitational accelerations. These experiments are the first to collect wheel–soil interaction imagery and force/torque sensor data alongside wheel sinkage data. Results from reduced-gravity flights are compared with on-ground experiments with all parameters equal, including wheel load, such that the only difference between the experiments is the effect of gravity on the soil itself. In lunar gravity, a statistically significant average reduction in traction of 20% is observed compared with 1 g, and in martian gravity an average traction reduction of 5–10% is observed. Subsurface soil imaging shows that soil mobilization increases as gravity decreases, suggesting a deterioration in soil strength, which could be the cause of the reduction in traction. Statistically significant increases in wheel sinkage in both martian and lunar gravity provide additional evidence for decreased soil strength. All of these observations (decreased traction, increased soil mobilization, and increased sinkage) hinder a rover’s ability to drive, and should be considered when interpreting results from reduced-load mobility tests conducted on Earth.


Author(s):  
R. J. Shavelson

Project Apollo has stimulated extensive research on human performance using a variety of lunar gravity simulators. Based on a survey of the literature, the following conclusions have emerged: (a) Existing simulators do not represent a high fidelity simulation of 1/6 g, (b) A validation study of the various simulators is needed, (c) Man will be capable of self-locomotion in lunar gravity, (d) Man's metabolic rate will be lower in 1/6 g during self-locomotion, (e) Man will change his method of performing common Earth tasks when in 1/6 g, (f) Psychomotor task decrement in 1/6 g will be observed, (g) Future research should direct itself toward a higher fidelity simulation of the total lunar ecology for study of mission-specific tasks.


2008 ◽  
Vol 44 ◽  
pp. 11-26 ◽  
Author(s):  
Ralph Beneke ◽  
Dieter Böning

Human performance, defined by mechanical resistance and distance per time, includes human, task and environmental factors, all interrelated. It requires metabolic energy provided by anaerobic and aerobic metabolic energy sources. These sources have specific limitations in the capacity and rate to provide re-phosphorylation energy, which determines individual ratios of aerobic and anaerobic metabolic power and their sustainability. In healthy athletes, limits to provide and utilize metabolic energy are multifactorial, carefully matched and include a safety margin imposed in order to protect the integrity of the human organism under maximal effort. Perception of afferent input associated with effort leads to conscious or unconscious decisions to modulate or terminate performance; however, the underlying mechanisms of cerebral control are not fully understood. The idea to move borders of performance with the help of biochemicals is two millennia old. Biochemical findings resulted in highly effective substances widely used to increase performance in daily life, during preparation for sport events and during competition, but many of them must be considered as doping and therefore illegal. Supplements and food have ergogenic potential; however, numerous concepts are controversially discussed with respect to legality and particularly evidence in terms of usefulness and risks. The effect of evidence-based nutritional strategies on adaptations in terms of gene and protein expression that occur in skeletal muscle during and after exercise training sessions is widely unknown. Biochemical research is essential for better understanding of the basic mechanisms causing fatigue and the regulation of the dynamic adaptation to physical and mental training.


2004 ◽  
Vol 171 (4S) ◽  
pp. 496-497
Author(s):  
Edward D. Matsumoto ◽  
George V. Kondraske ◽  
Lucas Jacomides ◽  
Kenneth Ogan ◽  
Margaret S. Pearle ◽  
...  

2015 ◽  
Vol 31 (1) ◽  
pp. 20-30 ◽  
Author(s):  
William S. Helton ◽  
Katharina Näswall

Conscious appraisals of stress, or stress states, are an important aspect of human performance. This article presents evidence supporting the validity and measurement characteristics of a short multidimensional self-report measure of stress state, the Short Stress State Questionnaire (SSSQ; Helton, 2004 ). The SSSQ measures task engagement, distress, and worry. A confirmatory factor analysis of the SSSQ using data pooled from multiple samples suggests the SSSQ does have a three factor structure and post-task changes are not due to changes in factor structure, but to mean level changes (state changes). In addition, the SSSQ demonstrates sensitivity to task stressors in line with hypotheses. Different task conditions elicited unique patterns of stress state on the three factors of the SSSQ in line with prior predictions. The 24-item SSSQ is a valid measure of stress state which may be useful to researchers interested in conscious appraisals of task-related stress.


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