Search Results

In support of this project, a trade study was conducted at the Jet Propulsion Laboratory on the mechanically pumped two-phase and single-phase thermal loops for lunar habitats located at the South Pole for the LAT II architecture.

A model is being developed to quantitatively compare and thus assist in the selection of systems and technology options for defined missions envisioned in NASA's Space Exploration Initiative. It consists of a modular top-down hierarchical break-down of the life support systems (LSS) into subsystems, and further break-down of the subsystems into functional elements representing individual processing technologies. A series of papers entitled Human Life Support During Interplanetary Travel & Domicile are planned to describe the techniques and results. Parts I through V have focused on physical/chemical (P/C) Life Support Systems Analysis, with trade-off studies at the systems and technology levels for open and closed loop configurations. This paper discusses an extension to the Generic Modular Flow Schematic (GMFS) for P/C Life Support Systems by the addition of biological (Bio) processes.

Estimates of life-support system mass and power demands were generated using the Life Support Systems Analysis (LiSSA) tool for extra-terrestrial outposts. Parameters varied include the crew size, mission duration, power source, and operating-unit redundancy. Development of promising technologies could reduce launch costs by over $30 million but R&D investment is required. Biological food production technologies are power intensive requiring an order of magnitude more power than physical/chemical air/water regenerative systems. The cost of launching and operating a food production facility is justified by the cost of resupply of food if the mission duration is of the order of several years. A system utilizing food production is, by definition, a highly-recycled and closed-loop system; modeling efforts for such systems should rigorously keep track of all chemical species that have a significant impact on crew survival and processing demands.

Thermal characterization was performed on a vapor compression heat pump using a novel, hybrid two phase loop design. Previous work on this technology has demonstrated its ability to provide passive phase separation and flow control based on capillary action. This provides high quality vapor to the compressor without relying on gravity-based phase separation or other active devices. This paper describes the subsequent work done to characterize evaporator performance under various startup scenarios, tilt angles, and heat loads. The use of a thermal expansion valve as a method to regulate operation was investigated. The effect of past history of use on startup behavior was also studied. Testing under various tilt angles showed evaporator performance to be affected by both adverse and favorable tilts for the given compressor. And depending on the distribution of liquid in the system upon startup, markedly different performance can result for the same system settings and heat loads.

NASA's proposed lunar lander, Altair, will be exposed to vastly different external temperatures following launch till its final destination on the moon. In addition, the heat rejection is lowest at the lowest environmental temperatures (0.5 kW @ 4K) and highest at the highest environmental temperature (4.5 kW @ 215K). This places a severe demand on the radiator design to handle these extreme turn-down requirements. A radiator with digital turn-down capability is currently under study at JPL as a robust means to meet the heat rejection demands and provide freeze protection while minimizing mass and power consumption. Turndown is achieved by independent control of flow branches with isolating latch valves and a gear pump to evacuate the isolated branches. A bench-top test was conducted to characterize the digital radiator concept. Testing focused on the demonstration of proper valve sequencing to achieve turn-down and recharge of flow legs.