[1] We have studied the sublimation of ice buried beneath 200 mm of JSC Mars-1 model regolith under simulated Mars conditions. As expected, even thin layers of regolith cause large decreases in sublimation rate, up to one order of magnitude at 50 mm. When the depth of the regolith was 50 to 200 mm we detected water desorbing from the overlying layers for which we were able to determine a desorption coefficient of 1.45 ± 0.5 Â 10 À3 h À1 . After allowing for the effect of desorption, we found that the diffusion coefficient for water vapor through our regolith is 1.74 ± 0.70 Â 10 À4 m 2 s À1, in excellent agreement with theoretical values. We thus find that a 1-m thick layer of ice buried below a meter of regolith resembling JSC Mars-1 on Mars at 235 K would last $800 years. Citation: Chevrier, V.,

No abstract

Inflatable and other membrane structures are expected to become increasingly important in space exploration due to their light weight and low cost. Unlike rigid structures, these structures are typically fabricated of flexible polymers and require internal pressurization to achieve structural integrity. Due to this, inflatable structures are vulnerable to the harsh space environment and catastrophic failure from structural vibration. A MEMS-based health monitoring and control system (HMCS) for space inflatables has been developed at the University of Arkansas. Fabricated mostly from polymeric materials, the HMCS is lightweight, flexible and can be attached directly to the external surface of an inflatable to provide health monitoring. Structure-wise, the HMCS is a three-dimensional multichip module with a sensor layer at the top, a common polyimide substrate in the middle and an actuator layer at the bottom. The sensor layer consists of an interconnected network of MEMS sensors for monitoring the environmental conditions around the inflatable and also the structural vibration of the inflatable. The actuator layer, fabricated from electroactive polymers, provides a two-dimensional shape control capability to the HMCS. When operated with strain and vibration sensors in the sensor layer, the polymer actuator can deform the surface contour of the inflatable to remove 'wrinkles' and dampen structural vibration.

No abstract

No abstract