TFAWS Passive Thermal Session Thermal Design and TVAC

TFAWS Passive Thermal Session Thermal Design and TVAC Test Correlation of a Lunar Rover Prototype Jean-Frédéric Ruel, Jean-François Labrecque-P. (Maya HTT) Josh Newman (Canadensys Aerospace Corp. ) Donatas Mishkinis (Allatherm SIA) Guanghan Wang (CSA) Presented By Jean-François Labrecque-P. Thermal & Fluids Analysis Workshop TFAWS 2020 August 18 -20, 2020 Virtual Conference

Lunar Exploration Program in Canada • CSA has been preparing support to the international lunar surface exploration effort for more than a decade • Surface mobility & lunar night survival are 2 key topics that have received particular attention • The Mobility and Environmental Rover Integrated Technology (MERIT) project was conceived to close strategic knowledge gaps through prototyping & testing • This presentation’s focus is the Thermally Regulated Electronics Enclosure (TREE) – a thermal control system for lunar night survival and shadowed operation • Objectives of TREE in a nutshell: – Survive Lunar night without a radioactive heat source – Survive Lunar days with limited radiators – Essentially, a solar-powered lunar rover TFAWS 2020 – August 18 -20, 2020 2

MERIT Rover Description • The MERIT project used CSA’s PHASR lunar rover from the HERACLES architecture, as the vehicle design case – – – Medium-size body (330 kg) Life expectancy: 1 year, 400 km Dimensions (Lx. Wx. H) : 2 m x 1. 5 m x 1. 2 m Scientific payload Sample collection Solar-powered system • Design retains scalability to multiple vehicle classes TFAWS 2020 – August 18 -20, 2020 3

TREE Description • The TREE is essentially a functional spacecraft, with the following components: – OBC, PCDU, batteries, MDAs, IMU, camera, functional drivetrain • Thermal design : – – Internal avionics in thermally regulated enclosures Multi-Layer Insulation (MLI) Thermally insulating standoffs Novel LHP development TFAWS 2020 – August 18 -20, 2020 4

TVAC Test • Test performed at DFL’s facilities over 12 days • Shroud flooded with LN 2, heaters to simulate solar heating and solar panels loading • Several test cases to simulate operational scenarios and lunar night survival TFAWS 2020 – August 18 -20, 2020 5

TVAC Test Correlation • Objective: confirm power values over lunar night • Model developed using SC 3 D Space System Thermal – Structure, electronics, MLI and radiators modeled explicitly – Thermal washers modeled as temperature-dependent thermal coupling – LHPs modeled with temperature dependency • Correlation performed using 2 data sets TFAWS 2020 – August 18 -20, 2020 6

TVAC Test Correlation • Cold plateau correlation: – Representative of lunar night survival – Cryogenic temperatures (shroud flooded with LN 2) – Thermostatic heaters turned off and replaced by equivalent constant heat loads TFAWS 2020 – August 18 -20, 2020 7

TVAC Test Correlation • Design Space Exploration software used to get rough order of magnitude for couplings • Test imponderables not included in thermal model – Some manual tuning required • Precision is within a few degrees TFAWS 2020 – August 18 -20, 2020 8

TVAC Test Correlation • Hot plateau correlation: – Representative of lunar day with internal dissipations – Maximum power dissipation (750 W) – 475 W applied on the +Z radiator • Temperatures correlated within a few degrees TFAWS 2020 – August 18 -20, 2020 9

TVAC Test Correlation • Transient simulation using correlated model – Coupling values from the two correlated plateaus – Linearly interpolated temperature-dependent thermal couplings – Temperature-dependent LHPs • Results concur with test observations TFAWS 2020 – August 18 -20, 2020 10

Concluding Remarks • Correlation activity: – DSE software useful to obtain quickly ROM values – Precision limited by number of TCs – Precision sufficient with regards to the test objective • Thermal design: – Successful demonstration of new LHP technology – Performance better than initially expected – Confirmed feasibility of surviving lunar nights without RHU TFAWS 2020 – August 18 -20, 2020 11