BART & MARGE: robotic propellant production on Mars
Photo: Team lead Chloe Gentgen at the poster session with RASC-AL judge and current NASA Chief Technologist A. C. Charania, June 2022.
BART & MARGE is a fully integrated, fully mobile architecture with no fixed centralized infrastructure to reliably produce large quantities of Methalox bipropellant by 2037 from thick ice sheets at the mid-northern latitudes of Mars. This architecture was designed for the 2022 NASA RASC-AL design competition and was required to produce 50 t/yr of propellant on Mars using water from subsurface ice reserves, to operate for at least five years without human maintenance, and to be landed through one or more landings of 45 t and 300 m^3 each. The desired system-level attributes were high reliability and operational flexibility.
Based on per-ton proxy risk metrics such as cumulative travel distance, material transfer connections/disconnections, and boreholes drilled, distributed architectures of fixed infrastructure served by resource acquisition rovers were ruled out, and the design space for a fully integrated, fully mobile approach was explored. BART, which stands for Bipropellant All-in-one in-situ Resource utilization Truck, is an end-to-end “ice to propellant” system and includes a RedWater drill, scroll compressors, water electrolysis and Sabatier reaction chambers, cryocoolers, heat exchangers, fuel cells, 25 t storage tanks and pumps to deliver propellant to the customer. It is powered by MARGE, the Mobile, Autonomous Reactor Generating Electricity, our mobile power truck design based on NASA’s upcoming 40 kWe fission surface power reactor.
Figure: the autonomous mobile resource harvester and propellant factory, storage and distribution truck BART produces the rocket propellants liquid methane (LCH4) and liquid oxygen (LOX) using subsurface water ice (H2O) and atmospheric carbon dioxide (CO2) on Mars. The required power is provided by the mobile 40kWe fission surface power unit, MARGE. Prospecting and utility services are provided by a Perseverance-class LISA (Looking for Ice Scouting Assistant) rover. For robust scaling of propellant production and storage, more BART + MARGE pairs can be added. BART is designed for autonomy before humans arrive on Mars, and for easy maintainability once humans are there.
The proposed campaign includes a precursor ice scouting and de-risking mission, and a main mission with 4 tandems of BART & MARGE. Each BART has a nominal production capacity of 35 t/yr, making the campaign double-fault tolerant. Other risk-reduction features include material flow connections tested and sealed on Earth, ready to produce on Mars with just a power cable connection, and a technology demo of BART & MARGE during the precursor mission.
The integrated approach enables synergies such as reusing waste heat to save energy, fully utilizing available energy sources, and gives rise to new capabilities such as delivering propellant to any Mars ascent vehicle location while also enabling simple scaling of production in the future. The campaign can be executed with four volume-limited Starship flights of 45 t each. MIT’s BART & MARGE is innovative, resilient, feasible, and scalable and can supply Methalox on Mars at a 15-year average cost of $1.2m per ton.
Video: 2-minute proposal video describing the BART + MARGE concept.
The BART & MARGE architecture won the First Place Overall and Best in Theme: Mars Water-based ISRU Awards at the 2022 NASA RASC-AL Forum. The RASC-AL website hosts a copy of the technical paper, technical poster and video recording of the final presentation.
My colleagues on this team were Chloe Gentgen (team lead), Guillem Cadesus-Vila, John Posada, Mindy Long, Laasya Nagareddy, Jaya Kambhamapaty, Marina Ten-Have, Madelyn Hoying, and the faculty advisors were Dr. Jeffrey Hoffman, and Dr. Olivier de Weck. My formal role in this project was as team sponsor, mentor and advisor. My main contributions were: (1) the concept of integrating resource harvesting, propellant production, storage and distribution on one large-truck to exploit various synergies, robustly make all material flow connections before launch, and enable a scalable, distributed and robust propellant production architecture (2) the selection of the 40kWe fission surface power source to align with the latest NASA investments and the concept to make it mobile, (3) the identification of a range of operational flexibilities and (4) the enunciation of the three proxy metrics for risk which were used to 'quantify' the potential robustness of this novel architecture relative to conventional approaches: cumulative travel distance, material transfer connections/disconnections, and number of boreholes drilled, all per ton of propellant.