‘‘Fast track’’ lunar NTR systems assessment for NASA’s first lunar outpost and its evolvability to Mars

Integrated systems and missions studies are presented for an evolutionary lunar‐to‐Mars space transportion system (STS) based on nuclear thermal rocket (NTR) technology. A ‘‘standardized’’ set of engine and stage components are identified and used in a ‘‘building block’’ fashion to configure a variety of piloted and cargo, lunar and Mars vehicles. The reference NTR characteristics include a thrust of 50 thousand pounds force (klbf), specific impulse (I_sp) of 900 seconds, and an engine thrust‐to‐weight ratio of 4.3. For the National Aeronautics and Space Administration’s (NASA) First Lunar Outpost (FLO) mission, an expendable NTR stage powered by two such engines can deliver ∼96 metric tonnes (t) to trans‐lunar injection (TLI) conditions for an initial mass in low Earth orbit (IMLEO) of ∼198 t compared to 250 t for a cryogenic chemical system. The stage liquid hydrogen (LH₂) tank has a diameter, length, and capacity of 10 m, 14.5 m and 66 t, respectively. By extending the stage length and LH₂ capacity to ∼20 m and 96 t, a single launch Mars cargo vehicle could deliver to an elliptical Mars parking orbit a 63 t Mars excursion vehicle (MEV) with a 45 t surface payload. Three 50 klbf engines and the two standardized LH₂ tanks developed for the lunar and Mars cargo vehicles are used to configure the vehicles supporting piloted Mars missions as early as 2010. The ‘‘modular’’ NTR vehicle approach forms the basis for an efficient STS able to handle the needs of a wide spectrum of lunar and Mars missions.