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Dual Fuel Solar Thermal Propulsion for LEO to GEO Transfer: Ideal Rocket Analysis

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Technical paper

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Analysis of a dual fuel solar thermal propulsion concept was performed based on a system designed at NASAs Marshall Space Flight Center. The MSFC system uses a single fuel, hydrogen, to transfer 1,000 pounds of payload from LEO to GEO. Ammonia and hydrogen are used by the dual fuel system and both propellants were considered for use in the early stages of the mission. However, it was found that a system burning ammonia first was more suitable for the given mission. A fixed gross weight and the ideal rocket equation were used to calculate component weights. The analysis included some propellant losses. Payload weight was initially decreased by the addition of ammonia but it was increased by downsizing the power system to provide 2 potind of thrust with ammonia instead of with hydrogen. The analysis indicated that 1,000 pounds of payload could be placed into geosynchronous orbit with ammmonia fraction of about 14 percent of the gross weight. The tank volume was decreased by 20 percent and the propellant lost to boiloff was decreased by 24 percent. Also, thrust to weight variation with change in ammonia weight fraction was examined. Further analysis is required to fully weigh the benefits of a dual fuel solar thermal system.

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  • Rocket Propellants

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