Thermal Design and Validation of the Mars 2020 Gas Dust Removal Tool (gDRT)

Date

2019-07-07

Journal Title

Journal ISSN

Volume Title

Publisher

49th International Conference on Environmental Systems

Abstract

As part of the science goals for the planned Mars 2020 mission, two instruments, PIXL and SHERLOC, intend to study the fine scale make up rocks, minerals, organic molecules, and potential biosignatures. These two instruments are planned to be used on smooth surfaces that are free of dust and other particles. Such surfaces are prepared by using a drill with an abrading bit; residual dust and particles are then removed using a compressed gas system—the Gas Dust Removal Tool (gDRT). The gDRT stores nitrogen gas in a supply tank. When ready for use the gDRT transfers some gas to a plenum tank via redundant supply valves. A run valve then releases the plenum tank gas through a nozzle onto the abraded surface. Early in the design process a risk was identified that the valves could potentially leak below the manufacture’s rated temperature of -20C. To mitigate this risk a parallel path was implemented: 1) try to qualify the valves to -135C and quantify leak rates at low temperature, and 2) implement the capability of survival heating in case qualification efforts are unsuccessful. Thermal design for the survival heating emphasized the need to minimize energy. The valve assembly is mounted to the gDRT baseplate via G10 isolators, and is fully enclosed in an SLI shield that provides a dual function of blocking forced convection and creating a CO2 gas gap for insulation. Two patch heaters on the valve assembly are thermostatically controlled to a setpoint of -65C to -73C. This setpoint was selected as a tradeoff between survival energy and leaking risk. Thermal testing of gDRT is scheduled for January 2019. This testing will validate the thermal design and enable thermal model correlation in order to provide more accurate survival energy predictions.

Description

Edgardo Farias, Jet Propulsion Laboratory (JPL), USA
Elizabeth Jens, Jet Propulsion Laboratory (JPL), USA
Barry Nakazono, Jet Propulsion Laboratory (JPL), USA
Jason Kempenaar, Jet Propulsion Laboratory (JPL), USA
Keith Novak, Jet Propulsion Laboratory (JPL), USA
ICES102: Thermal Control for Planetary and Small Body Surface Missions
The 49th International Conference on Environmental Systems was held in Boston, Massachusetts, USA on 07 July 2019 through 11 July 2019.

Keywords

Mars, Rover, Dust removal, Payload, Thermal control, Survival heater

Citation