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Vehicle and mission design options for the human exploration of mars/phobos using "bimodal" ntr and lantr propulsion. revised dec. 1998
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Borowski, Stanley K. McGuire, Melissa L. Dudzinski, Leonard A. |
| Copyright Year | 2002 |
| Description | The nuclear thermal rocket (NTR) is one of the leading propulsion options for future human missions to Mars because of its high specific impulse (lsp~850-1000 s) capability and its attractive engine thrust-to-weight ratio (~3-10). To stay within the available mass and payload volume limits of a âMagnumâ heavy lift vehicle, a high performance propulsion system is required for trans-Mars injection (TMI). An expendable TMI stage, powered by three 15 thousand pounds force (klbf) NTR engines is currently under consideration by NASA for its Design Reference Mission (DRM). However, because of the miniscule burnup of enriched uranium-235 during the Earth departure phase (~10 grams out of 33 kilograms in each NTR core), disposal of the TMI stage and its engines after a single use is a costly and inefficient use of this high performance stage. By reconfiguring the engines for both propulsive thrust and modest power generation (referred to as âbimodalâ operation), a robust, multiple burn, âpower-richâ stage with propulsive Mars capture and reuse capability is possible. A family of modular âbimodalâ NTR (BNTR) vehicles are described which utilize a common âcoreâ stage powered by three 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 (LH2) storage, and high data rate communications. An innovative, spine-like âsaddle trussâ design connects the core stage and payload element and is open underneath to allow supplemental âin-lineâ propellant tanks and contingency crew consumables to be easily jettisoned to improve vehicle performance. A âmodifiedâ DRM using BNTR transfer vehicles requires fewer transportation system elements, reduces IMLEO and mission risk, and simplifies space operations. By taking the next logical stepâuse of the BNTR for propulsive capture of all payload elements into Mars orbitâthe power available in Mars orbit grows to 150 kWe compared to 30 kWe for the DRM. Propulsive capture also eliminates the complex, higher risk aerobraking and capture maneuver which is replaced by a simpler reentry using a standardized, lower mass âaerodescentâ shell. The attractiveness of the âall BNTRâ option is further increased by the substitution of the lightweight, inflatable âTransHabâ module in place of the heavier, hard-shell hab module. Use of TransHab introduces the potential for propulsive recovery and reuse of the BNTR / Earth return vehicle (ERV). It also allows the crew to travel to and from Mars on the same BNTR transfer vehicle thereby cutting the duration of the ERV mission in halfâfrom ~4.7 to 2.5 years. Finally, for difficult Mars options, such as Phobos rendezvous and sample return missions, volume (not mass) constraints limit the performance of the âall LH2â BNTR stage. The use of âLOX-augmentedâ NTR (LANTR) engines, operating at a modest oxygen-to-hydrogen mixture ratio (MR) of 0.5, helps to increase âbulkâ propellant density and total thrust during the TMI burn. On all subsequent burns, the bimodal LANTR engines operate on LH2 only (MR=0) to maximize vehicle performance while staying within the mass limits of two Magnum launches. |
| File Size | 4255226 |
| Page Count | 54 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20030014643 |
| Archival Resource Key | ark:/13960/t4qk2cf69 |
| Language | English |
| Publisher Date | 2002-12-01 |
| Access Restriction | Open |
| Subject Keyword | Nuclear Thermal Rocket Ntr Lantr Bimodal In-situ Resource Utilization High Thrust Nuclear Propulsion Mars Phobos Spacecraft Liquid Oxygen Mars Planet In Situ Resource Utilization Manned Space Flight Spacecraft Design Cryogenic Rocket Propellants Mars Missions Spacecraft Propulsion Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
