ESCORT: A Pratt and Whitney nuclear thermal propulsion and power system for manned mars missions
- United Technologies, Pratt-Whitney, West Palm Beach, Florida 33410 (United States)
The purpose of this paper is to describe the conceptual design of an upgrade to the Pratt and Whitney ESCORT nuclear thermal rocket engine. The ESCORT is a bimodal engine capable of supporting a wide range of vehicle propulsive and electrical power requirements. The ESCORT engine is powered by a fast-spectrum beryllium-reflected CERMET-fueled nuclear reactor. In propulsive mode, the reactor is used to heat hot hydrogen to approximately 2700 K which is expanded through a converging/diverging nozzle to generate thrust. Heat pickup in the nozzle and the radial beryllium reflectors is used to drive the turbomachinery in the ESCORT expander cycle. In electrical mode, the reactor is used to heat a mixture of helium and xenon to drive a closed-loop Brayton cycle in order to generate electrical energy. This closed loop system has the additional function of a decay heat removal system after the propulsive mode operation is discontinued. The original ESCORT design was capable of delivering 4448.2 N (1000 lbf) of thrust at a vacuum impulse level of approximately 900 s. Design Reference Mission requirements (DRM) from NASA Johnson Space Center and NASA Lewis Research Center studies in 1997 and 1998 have detailed upgraded requirements for potential manned Mars missions. The current NASA DRM requires a nuclear thermal propulsion system capable of delivering total mission requirements of 200170 N (45000 lbf) thrust and 50 kWe of spacecraft electrical power. This is met assuming three engines capable of each delivering 66723 N (15000 lbf) of vacuum thrust and 25 kWe of electrical power. The individual engine requirements were developed assuming three out of three engine reliability for propulsion and two out of three engine reliability for spacecraft electrical power. The approximate target vacuum impulse is 925 s. The Pratt and Whitney ESCORT concept was upgraded to meet these requirements. The hexagonal prismatic fuel elements were modified to address the uprated power requirements while maintaining the peak fuel temperature below the 2880 K limit for W-UO{sub 2} CERMET fuels. A system integrated performance methodology was developed to assess the sensitivity to weight, thrust and impulse to the DRM requirements. Propellant tanks, shielding, and Brayton cycle power conversion unit requirements were included in this evaluation.
- OSTI ID:
- 21202509
- 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: 10.1063/1.57547; (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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Related Subjects
AFTER-HEAT REMOVAL
BERYLLIUM
BRAYTON CYCLE
CERMETS
DESIGN
EVALUATION
FUEL ELEMENTS
HELIUM
MARS PLANET
NASA
NUCLEAR FUELS
PERFORMANCE
PROPULSION SYSTEMS
ROCKET ENGINES
SPACE FLIGHT
SPACE POWER REACTORS
TURBOMACHINERY
URANIUM DIOXIDE
XENON
NESDPS Office of Nuclear Energy Space and Defense Power Systems