Suitability of reusability and in-situ propellant production for a Lunar transportation system

Abstract

Sustainable continuous presence on the Moon is a long term goal of humankind. However, the few vehicles that were built until now for lunar missions were far from having the capability to achieve this goal. Their designs were mainly influenced by short term considerations and the available technological state of the art. Consequently relying on a classic expendable transportation system based on storable propellant will not allow going much further than where we arrived until today. A new transportation architecture is needed. In the frame of the ROBEX (Robotic Exploration under Extreme Conditions) project, new types of lunar architecture are under study. Modularity, reconfigurability and flexibility are playing a major role. The transportation system is of course a very important aspect of future Moon missions, as it can represent a very large share of the mass to be launched from Earth. Reducing the share of the lunar transportation system within the total mass launched from Earth is the best way to reduce the cost of Moon missions and therefore increase the overall programme sustainability. The preliminary design of a Moon transportation system based on reusable vehicles running on LOx/LH2 and benefiting from lunar in-situ propellant production is being performed. This transportation system is made out of two types of vehicle. The Reusable Lunar Resupply Vehicle (RLRV) is a lunar single stage to orbit vehicle able also to land on the Moon. The Reusable Trans- Lunar Vehicle (RTLV) is a space-tug able to transport payloads from LEO to a cis-lunar orbit and back. Several cislunar orbits are considered and their influence on the RLRV and RTLV designs is discussed. Possible vehicle cooperation, such as in-space cryogenic propellant transfer is also studied. For both vehicles, a structural preliminary sizing is performed. For the RLRV in particular, the landing dynamic has been analysed to refine the landing loads. Based on these results, the potential gain brought by reusability to the Lunar transportation system is demonstrated for different cis-lunar staging orbits and operational modes.