Evanoff, J. | Search NASA

NASA NTRS2004

Mars Surface Analog Project: Preparing for Astronauts' First Hours on Mars

Astronaut missions to Mars may be decades in the future, but contemporary estimates of the physical capabilities of the crewmembers upon arrival after prolonged transit can guide development of operational requirements to be imposed on them. Requirements for functional capacities will differ depending on whether they land in a spartan ascent vehicle or in a well-equipped habitat, but each of those options brings with it certain operational risks. Rehabilitation will be an important factor for crew health, safety and efficiency after the multi-month transit from Earth. Specific recommendations will be stipulated for the time to be allotted for on-planet rehabilitation before the first planned surface excursion, such as the transfer from the ascent-lander to the habitat-lander. Three sequential workshops (the third including extramural experts in appropriate fields) examined the likely capabilities of crewmembers shortly after landing on Mars, the predicted operational requirements they will face, and the near-term steps to close the gap between the requirements and capabilities.

Charles, J.↗

NASA NTRS1992

Human ocular torsion during parabolic flights: an analysis with scleral search coil

Rotation of the eyes about the visual axis is known as ocular torsion. A lateral inclination (a "roll") of the head induces ocular torsion in the opposite direction, a response known as ocular counterrolling. For six subjects, we recorded the static (head still) and dynamic (head in oscillatory roll motion) ocular torsion in normal 1 g condition and also during the microgravity and hypergravity periods of parabolic flight, using the electromagnetic scleral search coil technique. With the head still, the direction and magnitude of torsion that occurred in response to microgravity and hypergravity differed substantially from one individual to another, but there was a significant difference in torsional magnitude between the microgravity and hypergravity periods, for all static head positions including the upright position. Under normal 1 g conditions, counterrolling compensated for about 16% of (voluntary) static head roll, while dynamic counterroll was much larger, up to 36% of head roll at 0.55 Hz. With increasing frequency of head oscillation between 0.33 Hz and 0.55 Hz, the gain of counterrolling increased and there was no change in the phase relationship. The gain of dynamic counterroll (in response to voluntary head rolling) was not significantly less in hypogravity, suggesting that on the ground at these frequencies the contribution of gravity and gravity receptors to this reflex is redundant: this reflex is probably driven by the semicircular canals. In some subjects, the torsional displacement in microgravity is accompanied by micro-torsional oscillatory motion.

Non-NASA Center↗