Kiloton Class ISRU Systems for LO₂/LCH₄ Propellant Production on the Mars Surface

As part of the 2023 strategic analysis cycle the NASA Mars Architecture Team wanted to explore what it takes to produce many hundreds of tons of in-situ propellants for a large vertical lander. The conceptual operations and design of the LOX/LCH₄ ISRU water acquisition, gas extraction and liquification system was assigned to the NASA Compass concurrent engineering team with support from various NASA ISRU, cryogenic fluid management, and surface power experts. The conceptual point design settled on producing 300t of LOX/LCH₄ from the Mars atmosphere and water in 20 months and storing the liquified propellants in a to be reused lander. Several of these large Single Stage, all chemical class large vertical landers would deliver the required ISRU equipment. The required 150t of water stock for the ISRU system was traded to be delivered, pumped from subsurface ice deposits or extracted from surface soils. The large propellant gas production systems consist of atmospheric CO₂ collection scroll pumps, a combined solid oxide electrolysis and methanation system to convert the CO₂ and water into gaseous oxygen and methane, and various driers, scrubbers, and separators to remove the excess water, CO₂ and H₂. The liquification system consisted of 90 K cryocoolers to provide cold Ne to the launch vehicle tanks to liquify these CO₂ and oxygen gases and store them as rocket propellants. The systems are deployed using a 6t capable chassis derived from earlier pressurized rover designs. In total the gas production and liquification systems required two gas production pallets, two liquification pallets, two water tankers, and six, 40 kW fission surface power systems with cabling. All of this equipment was found to notionally fit inside two LVLs. For the required 150t of water, either two landers could deliver it to Mars, or a single lander could deliver water ice drill rigs, or two landers could deliver the surface mining equipment. A comparison of approaches in terms of number of landers, number and type of elements, power and time is made.