Design Considerations for Space Transfer Vehicles Using Solar Thermal Propulsion
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HUNTSVILLE AL GEORGE C MARSHALL SPACE FLIGHT CENTER
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The economical deployment of satellites to high energy earth orbits is crucial to the ultimate success of this nations commercial space ventures and is highly desirable for deep space planetary missions requiring earth escape trajectories. Upper stage space transfer vehicles needed to accomplish this task should ideally be simple, robust, and highly efficient. In this regard, solar thermal propulsion is particularly well suited to those missions where high thrust is not a requirement. The Marshall Space Flight Center is, therefore, currently engaged in defining a transfer vehicle employing solar thermal propulsion capable of transferring a 450 kg payload from Low Earth Orbit LEO to Geostationary Earth Orbit GEO using a Lockheed Launch Vehicle LLV3. The current design uses liquid hydrogen as the propellant and employs two inflatable elliptical off-axis parabolic solar collectors to focus sunlight onto a tungstenrhenium black body type absorber. The concentration factor on this design is projected to be approximately 1,8001 for the primary collector and 31 for the secondary collector for an overall concentration factor of nearly 54001. The engine, which is about twice as efficient as the best currently available chemical engines, produces 8.9 N of thrust with a specific impulse Isp of 860 sec. Transfer times to GEO are projected to be on the order of one month.
- Combustion and Ignition
- Unmanned Spacecraft
- Spacecraft Trajectories and Reentry