From Importing to Exporting: The Impact of ISRU on Space Logistics

Abstract

Lunar in situ resource utilization (ISRU) can reduce Earth-to-orbit (ETO) launch requirements up to 90% and new system mass 40-70% relative to the Constellation Program in support of a permanent lunar Outpost. ISRU can improve cargo hardware content as much as 104% by providing waste water replenishment. Propellant exports to Earth-Moon Lagrange Point 1 (EML1) and LEO in support of human exploration missions to near Earth objects (NEO) and Mars are also possible given lunar ISRU. To become a net exporter, a lunar Outpost must deliver more propellant to a customer than it receives in cargo from Earth. The transition from an importing to a net exporting lunar Outpost begins with a pilot plant producing 3.8 – 24.2 metric tons (t) of water per year to supply the Outpost with water and oxygen. In addition, reusable cislunar transportation system propellant requirements must be met by ISRU production. A reusable cislunar transportation architecture (RCTA) with 5.5 mixture ratio (MR) rocket engines requires 1870 t of propellant from 2590 t of water leaving 720 t of oxygen byproduct on the Moon with 269 t loss allowance to support two crew and cargo missions per year. Exporting 50 t lunar ISRU of propellant requires 885 t of water production delivering 18.5 t of propellant to the EML1 propellant depot and 33.8 t to the LEO propellant depot. Therefore, lunar ISRU net export status is achieved once water production levels exceed 3475 t per year. Water production requirements can be reduced 33% and oxygen by-product eliminated by using stoichiometric rocket engines, achieving 1% transfer loss rate, and transporting water to depots for propellant production.