Human exploration and settlement of the moon using lunox-augmented NTR propulsion

Abstract

An innovative trimodal nuclear thennal rocket (NTR) concept is described which combines conventional liquid hydrogen (LHJ-cooled NTR, Brayton cycle power generation and supersonic combustion ramjet (scramjet) technologies. Known as the liquid oxygen (LOX)-augmented NTR (LANTR), this concept utilizes the large divergent section of the N1R nozzle as an "afterburner" into which LOX is injected and supersonically combusted with nuclear preheated hydrogen emerging from the LAN1R's choked sonic throat-"scramjet propulsion in reverse." By varying the oxygen-to-bydrogen mixture ratio (MR), the LANfR can operate over a wide range of thrust and specific impulse (Isp) values while the reactor core power level remains relatively constant As the MR varies from zero to seven, the thrust-to-weight ratio for a 15 thousand pound force (ldbf) NTR increases by -440%-from 3 to 13-while the lsp decreases by only -45%-from 940 to 515 seconds. This thrust augmentation feature of the LANTR means that "big engine" perfonnance can be obtained using smaller, more affordable, easier to test NTR engines. "Reoxidizing" the bipropellant LAN1R system in low lunar orbit (ILO) with high density "lunar-derived" LOX (LUNOX) enables a reusable, reduced size and mass lunar transfer vehicle (LTV) which can be deployed and resupplied using two 66 t-class SbuttIe-derived launch vehicles. The reusable LANTR can also transport 200 to 300% more payload on each piloted round trip mission than an expendable "all LH 2 " NTR system. As initial outposts grow to eventual lunar settlements and LUNOX production capacity increases, the LANTR concept can also enable a rapid "commuter" shuttle capable of 36 to 24 hour "one way" trips to the Moon and back with reasonable size vehicles and initial mass in low Earth orbit (IMLEO) requirements.