The realization of the renewed exploration of the moon presents many technical challenges; among them is the survival of lunar surface assets during periods of darkness when the lunar environment is very cold. Thermal wadis are engineered sources of stored solar energy using modified lunar regolith as a thermal storage mass that can enable the operation of lightweight robotic rovers or other assets in cold, dark environments without incurring potential mass, cost, and risk penalties associated with various onboard sources of thermal energy. Thermal wadi-assisted lunar rovers can conduct a variety of long-duration missions including exploration site surveys; teleoperated, crew-directed, or autonomous scientific expeditions; and logistics support for crewed exploration. This paper describes a thermal analysis of thermal wadi performance based on the known solar illumination of the moon and estimates of producible thermal properties of modified lunar regolith. Analysis was performed for the lunar equatorial region and for a potential Outpost location near the lunar south pole. The results are presented in some detail in the paper and indicate that thermal wadis can provide the desired thermal energy reserve, with significant margin, for the survival of rovers or other equipment during periods of darkness.

This paper discusses a method used for the systematic improvement of NASA's Lunar Surface Systems avionics architectures in the area of reliability and faulttolerance. This approach utilizes an integrated system model to determine the effects of component failure on the system's ability to provide critical functions. A Markov model of the potential degraded system modes is created to characterize the probability of these degraded modes, and the system model is run for each Markov state to determine its status (operational or system loss). The probabilistic results from the Markov model are first produced from state transition rates based on NASA data for heritage failure rate data of similar components. An additional set of probabilistic results are created from a representative set of failure rates developed for this study, for a variety of component quality grades (space-rated, mil-spec, ruggedized, and commercial). The results show that careful application of redundancy and selected component improvement should result in Lunar Surface Systems architectures that exhibit an appropriate degree of faulttolerance, reliability, performance, and affordability. 12

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For the past three years, our team has been developing, refining, and maturing a unique solar array technology known as Stretched Lens Array SquareRigger (SLASR). As described in this paper, SLASR offers an unprecedented portfolio of performance metrics, including:· Areal Power Density = 300 -400 W/m 2 · Specific Power = 300 W/kg -500 W/kg · Stowed Power = 80 -120 kW/m 3