Low-Cost Uncrewed Lunar Landers: Mission Design and Preliminary Feasibility Assessment

Lunar exploration is poised for a renaissance. The Artemis program intends to create a permanent humanpresence on the moon. There has been much research and development interest in launchers, crew vehiclesand habitats for lunar outposts. These lunar outposts will necessitate regular two-way cargo deliveriesbetween the Earth and the Moon. Since space transport costs are so high compared to terrestrial shippingcosts, it is interesting to investigate cost-effective and suitable ways of delivering cargo to a human lunaroutpost. This paper uses a systems engineering approach to identify, evaluate and size a set of five possiblemission architectures for unmanned cargo delivery from Earth to the lunar surface. The first three missionarchitectures are fully reusable, single-stage, two-stage, and three-stage. The fourth uses a reusable electricspace tug, and the fifth is a non-reusable Apollo-style architecture. The five mission architectures are sizedusing statistically derived sizing rules from a database of 42 lunar landers and transfer vehicles compiledfrom an extensive literature review. Two sizing exercises were carried out for each architecture: (i) amaximalist case to understand the upper bound to the payload delivery mass, (ii) and a two tons payloaddelivery case comparable to the mass of ISS cargo deliveries. A trade-off is then performed based onseven figures of merit: Landed Payload [kg/trip] Returned Payload [kg/trip], Cost of Landed Payload[$/kg], Cost of Returned Payload [$/kg], Delivery Time [days], System Complexity and Extensibility. Themost cost-effective and suitable mission architecture is chosen, and a lander design which can carry twotons of cargo down to the lunar surface and back up again is sized from statistical and parametric sizingrules. This small lander is then costed using TruePlanning software. It is found that the main cost driversfor lunar cargo delivery are fuel carriage and launcher costs. These costs could be reduced by orbital fueldepots in LEO and at the Lunar Gateway, or by ride-sharing on very large launchers.