'Bimodal' NTR and LANTR propulsion for human missions to Mars/Phobos
- Launch Service and Transportation Project Office (United States)
- Systems Engineering Division NASA Lewis Research Center, Cleveland, Ohio 44135 (United States)
- Analex Corporation, Brook Park, Ohio 44145 (United States)
The nuclear thermal rocket (NTR) is one of the leading propulsion options for future human missions to Mars due to its high specific impulse (Isp {approx}850-1000 s) and attractive engine thrust-to-weight ratio ({approx}3-10). Because only a miniscule amount of enriched uranium-235 fuel is consumed in a NTR during the primary propulsion maneuvers of a typical Mars mission, engines configured for both propulsive thrust and modest power generation (referred to as 'bimodal' operation) provide the basis for a robust, 'power-rich' stage enabling propulsive Mars capture and reuse capability. A family of modular 'bimodal' NTR (BNTR) vehicles are described which utilize a common 'core' stage powered by three 66.7 kN ({approx}15 klbf) BNTRs that produce 50 kWe of total electrical power for crew life support, an active refrigeration/reliquification system for long term, 'zero-boiloff' liquid hydrogen (LH{sub 2}) storage, and high data rate communications. Compared to other propulsion options, a Mars mission architecture using BNTR transfer vehicles requires fewer transportation system elements which reduces mission mass, cost and risk because of simplified space operations. For difficult Mars options, such as a Phobos rendezvous and sample return mission, volume (not mass) constraints limit the performance of the 'all LH{sub 2}' BNTR stage. The use of 'LOX-augmented' NTR (LANTR) engines, operating at a modest oxygen-to-hydrogen (O/H) mixture ratio (MR) of 0.5, helps to increase 'bulk' propellant density and total thrust during the trans-Mars injection (TMI) burn. On all subsequent burns, the bimodal LANTR engines operate on LH{sub 2} only (MR=0) to maximize vehicle performance while staying within the mass limits of two {approx}80 t 'Magnum' heavy lift launch vehicles (HLLVs)
- OSTI ID:
- 21202497
- Journal Information:
- AIP Conference Proceedings, Vol. 458, Issue 1; Conference: Space technology and applications international forum - 1999, Albuquerque, NM (United States), 31 Jan - 4 Feb 1999; Other Information: DOI: 10.1063/1.57726; (c) 1999 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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