Future NASA Exploration Missions Research Articles

Compact Heat Rejection System Utilizing Integral Variable Conductance Planar Heat Pipe Radiator for Space Application

ABSTRACT In order to meet heat rejection requirements for future NASA exploration, scientific, and discovery missions, a study is being conducted for the feasibility of integral variable conductance planar heat pipe (VCPHP) technology. This represents a novel, low technology readiness level (TRL) heat rejection technology that, when developed, could operate efficiently and reliably across a wide range of thermal environments. The concept consists of a planar heat pipe whose evaporator acquires the excess thermal energy from the thermal control system and rejects it at its condenser whose outer surface acts as a radiating surface. The heat pipe is made from thermally conductive polymers in order to minimize its mass. It has a non-condensable gas that changes the active radiator surface depending on the heat load. A mathematical model of steady-state variable conductance heat pipe is developed. Two planar heat pipes are designed, fabricated, and tested to validate the theoretical model. The feasibility of the proposed VCPHP working in a space environment is discussed, based on the model.

Realistic Specific Power Expectations for Advanced Radioisotope Power Systems

Radioisotope power systems are being considered for a wide range of future NASA space science and exploration missions. Generally, radioisotope power systems offer the advantages of high reliability, long life, and predictable power production regardless of operating environment. Previous radioisotope power systems, in the form of radioisotope thermoelectric generators, have been used successfully on many NASA missions including Apollo, Viking, Voyager, and Galileo. NASA is currently evaluating design options for the next generation of radioisotope power systems. Of particular interest is the use of advanced, higher efficiency power conversion to replace the previous thermoelectric devices. Higher efficiency reduces the quantity of radioisotope fuel and potentially improves the radioisotope power systems specific power (watts per kilogram). Power conversion options include segmented thermoelectric, Stirling, Brayton, and thermophotovoltaic. This paper offers an analysis of the advanced 100 W-class radioisotope power system options and provides credible projections for specific power. Based on the analysis presented, radioisotope power system specific power values greater than 10 W/kg appear unlikely.

Next generation system and software architectures: Challenges from future NASA exploration missions

The four key objective properties of a system that are required of it in order for it to qualify as “autonomic” are now well-accepted—self-configuring, self-healing, self-protecting, and self-optimizing—together with the attribute properties—viz. self-aware, environment-aware, self-monitoring and self-adjusting. This paper describes the need for next generation system software architectures, where components are agents, rather than objects masquerading as agents, and where support is provided for self-* properties (both existing self-chop and emerging self-* properties). These are discussed as exhibited in NASA missions, and in particular with reference to a NASA concept mission, ANTS, which is illustrative of future NASA exploration missions based on the technology of intelligent swarms.