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The Phoenix Mars Lander is scheduled to be launched in August 2007 and will land in the northern Vastitas Borealis region. The lander is equipped with a suite of instruments designed to investigate the mineralogy and geochemistry of the soil and to study the atmosphere. The Canadian Meteorological Instrument (MET) will measure the location and the extent of clouds and the distribution of scatterers in the atmosphere as well as measuring the air temperature and the barometric pressure. The MET will provide Canadian scientists with a unique opportunity to study the Martian atmosphere and enhance our understanding of the planet in key areas of Canadian expertise. The MET instrument is composed of multiple elements in order to fulfil the science objectives. The MET Light Imaging Detection and Ranging (LIDAR) will probe the atmosphere by sending out laser pulses and measuring the backscattered returns.

Heat pipes, loop heat pipes and capillary pumped loops are heat transfer devices driven by capillary forces with high-effectiveness & performance, offering high-reliability & flexibility in varying g-environments. They are suitable for spacecraft thermal control where the mass, volume, and power budgets are very limited. The Canadian Space Agency is developing loop heat pipe hardware aimed at understanding the thermal performance of two-phase heat transfer devices and in developing numerical simulation techniques using thermo-hydraulic mathematical models, to enable development of novel thermal control technologies. This loop heat pipe consists of a cylindrical evaporator, compensation chamber, condenser along with vapor and liquid lines, which can be easily assembled/disassembled for test purposes. This laboratory setup is especially designed to enable the visualization of fluid flow and phase change phenomena.

This paper describes a new approach to spacecraft thermal control based on a passive thin-film smart radiator device (SRD) that employs a variable heat-transfer/emitter structure. The SRD employs an integrated thin-film structure based on V1-x-yMxNyOn that can be applied to existing Al thermal radiators. The SRD operates passively in response to changes in the temperature of the space structure. The V1-x-yMxNyOn exhibits a metal/insulator transition with temperature, varying from an IR transmissive insulating state at lower temperatures, to a semiconducting state at higher temperatures. Dopants, M and N, are employed to tailor the thermo-optic characteristics and the transition temperature of the passive SRD. The transition temperature can be preset over a wide range from below -30°C to above 68°C using suitable dopants. A proprietary SRD structure has been developed that facilitates emissivities below 0.2 to dark space at lower temperatures to reduce heater requirements.

The paper addresses the thermal control of a lunar lander/rover by use of heat pumps enabling payload heat to be rejected at a higher temperature to the lunar day environment. The heat pump technologies considered include absorption, vapor compression, adsorption, hybrid and chemical heat pumps technologies. A trade-off of the various heat pump technologies for a 2kW payload cooling capability is presented based on the needs of space-based hardware in terms of low mass and power, high performance, reliability and compactness of the systems. Finally the selection of a novel variant of the chemical heat pump concept is presented as a promising technology to be further investigated through breadboard development.

The thermal control of lunar landers/rovers necessitates the use of a system to allow heat rejection to the high temperature lunar environment. In this context a vapour compression heat pump which is a proven technology in terrestrial and aeronautical applications has been studied; its suitability in providing 2 kW cooling capability with adequate temperature lift for final heat rejection by space radiators is assessed. The stringent requirements of space-based hardware in terms of temperature lift, compactness, mass, performance and reliability necessitates optimization studies. Mass optimization of the heat pump components has been carried out, as well as selection of refrigerants and thermodynamic cycles most suited for the application.