A report proposes a small spacecraft attitude-control thruster in which the propellant material would be hydrazine that would be stored frozen until sublimed at the instant of use. From the upstream to the downstream end, the main components of the thruster would include a plug of solid hydrazine in a container, a rapid source of radiant heat (e.g., a laser diode or a flash lamp), and a heated-catalyst-and-nozzle assembly like that of a conventional hydrazine thruster. In operation, each pulse of radiant heat would cause a small amount of frozen hydrazine to sublime. The puff of hydrazine vapor thus generated would become chemically decomposed in the heated catalyst, and an impulse would be generated by the expansion of the puff of decomposition products in the nozzle. This thruster would be attractive for generating small impulses (impulse "bits") on command for precise maneuvering of a spacecraft that either remains below the freezing temperature of hydrazine (≈274 K) or that contains equipment to keep the hydrazine refrigerated.
This work was done by Larry Roe of Caltech for NASA's Jet Propulsion Laboratory. To obtain a copy of the report, "Subliming Solid Hydrazine Thruster," access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Machinery/Automation category.
NPO-20540
This Brief includes a Technical Support Package (TSP).
Thruster Based on Sublimation of Solid Hydrazine
(reference NPO-20540) is currently available for download from the TSP library.
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Overview
The document is a technical support package from NASA's Jet Propulsion Laboratory (JPL) detailing a novel thruster design based on the sublimation of solid hydrazine. This innovation addresses the need for advanced attitude control systems (ACS) in spacecraft, particularly for the X-2000 program, which requires thrusters with low mass, impulse bit, and power requirements.
Traditionally, hydrazine thrusters utilize liquid propellant stored in tanks, with valves controlling the flow. In contrast, this new system stores hydrazine in a solid form, which is vaporized using a heater, laser, or flash lamps. This method allows for the generation of small amounts of hydrazine vapor that can be directed into a conventional catalytic reactor, providing a more efficient and compact solution for spacecraft propulsion.
The document emphasizes the novelty of this approach, highlighting its improvements over prior art. By eliminating the need for liquid storage and complex valve systems, the solid hydrazine thruster design simplifies the propulsion mechanism, potentially reducing the overall weight and complexity of spacecraft systems. This is particularly beneficial for small spacecraft, where every gram of weight is critical.
The report also includes disclaimers regarding the information provided, stating that neither the United States Government nor NASA assumes any liability for the use of the information contained within the document. It clarifies that references to specific commercial products or processes do not imply endorsement by the government or JPL.
Overall, this technical support package presents a significant advancement in propulsion technology, showcasing a method that could lead to more efficient and reliable spacecraft operations. The solid hydrazine thruster represents a promising direction for future aerospace applications, aligning with the ongoing efforts to enhance the capabilities of small spacecraft in various missions. The document serves as a foundational report for further exploration and potential implementation of this innovative technology in the field of aerospace engineering.
