DTVAC Dusty Planetary Thermo-VACuum Simulator and LN2 Commissioning
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It is important to simultaneously simulate the combined effects of the lunar or Mars surface conditions (diurnal temperatures, levitated dust, ambient pressure and solar illumination) to verify the performance and reliability of critical assemblies to ensure their successful operation. The DTVAC facility combines a controlled dust simulant shower in vacuum with simulated solar illumination and thermal control of the test device from below -193°C to above +120°C. DTVAC includes a software-controlled large-area planetary dust simulant dispenser and electrostatic charger. The temperature-controlled platen can accommodate test devices up to 1.0mx0.9mx0.9m in volume, including surface (radiator), optical (spectrometer, imager), and mechanical (motors, gears) assemblies. DTVAC will be used to validate the operation of relevant payloads and processes under simulated lunar or Mars surface environmental conditions, including: • Day/night temperatures (<-232°C to >120°C), depending on the selected coolant and illumination, • Software-controlled dispersion rates of selected charged dust simulant, • Incident illumination to 1000 W/m2 with simulated solar spectrum, • Planetary atmospheric pressures (10-5 Torr (with dust) to 10-7 Torr relevant to the Moon and 3 to 12 Torr CO2 relevant to Mars). DTVAC was validated to provide continuous testing over periods exceeding 14 terrestrial days, equivalent to operation over a full lunar day or night, under computer control based on a user-selectable script. The planned LN2 upgrades were successfully integrated with the DTVAC system and experimentally validated through a sequence of tests. This included the LN2 automatic dewar interchange, LN2 flow control system, and exhaust system. This paper discusses the LN2 cooling upgrade and commissioning of the Dusty Thermo-Vacuum (DTVAC) planetary environment simulator. Temperatures near 80K were achieved on the 1mx1.1m platen with the LN2 cooling system. Preliminary cooling using liquid helium was also successfully tested on a smaller trial platen, using the LN2-cooled shroud as a thermal buffer.