A report proposes a liquid/vapor-hydrazine thruster for use in controlling the attitude of a small spacecraft. From the upstream to the downstream end, the thruster would include a tank containing liquid hydrazine, a fast liquid valve, a heated prevaporizing plenum, a fast gas valve, and a heated catalytic bed. In one mode of operation (the conventional mode), heat would not be supplied to the prevaporizing plenum; instead, liquid hydrazine would be fed directly to the heated catalytic bed. In another mode of operation, heat would be supplied to the prevaporizing plenum, and the gas valve would be opened in brief pulses to pass the hydrazine vapor to the heated catalytic bed to produce small pulses of thrust. The use of vapor (as compared with liquid) feed in the pulse mode would make it possible to generate smaller impulses, which are better suited for highly precise spacecraft maneuvers.
This work was done by Larry Roe of Caltech for NASA's Jet Propulsion Laboratory. To obtain a copy of the report, "Liquid/Vapor Millinewton Hydrazine Thruster," access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Machinery/Automation category.
NPO-20541
This Brief includes a Technical Support Package (TSP).
Liquid/Vapor-Hydrazine Thruster Would Produce Small Impulses
(reference NPO-20541) is currently available for download from the TSP library.
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Overview
The document outlines a technical report related to the development of a novel hydrazine thruster designed for use in spacecraft, specifically within the context of the X-2000 program. This innovative thruster features a prevaporizing plenum, which allows it to operate in two distinct modes: conventional continuous burns and minimum impulse-bit operation.
In the conventional mode, the plenum heater remains inactive, and the thruster functions similarly to traditional hydrazine thrusters. However, during minimum impulse-bit operation, the system utilizes prevaporized hydrazine, which is fed to a catalyst. This design enables the thruster to achieve much smaller mass throughputs, which is crucial for applications requiring precise control and maneuverability in space. The ability to use larger tanks helps mitigate concerns related to plugging, a common issue in thruster systems.
The motivation behind this development stems from the need for attitude control systems (ACS) that can deliver very small impulse bits while maintaining low mass and electrical power requirements, alongside high reliability. The report emphasizes that the introduction of a gas feed during bit operation allows for the passage of minimal amounts of hydrazine through the thruster for each valve cycle. This results in lower impulse bits compared to conventional liquid hydrazine systems, making the new thruster particularly advantageous for missions that demand fine-tuned adjustments.
The document also includes administrative details such as the report number, project classification, and the acknowledgment that the work was conducted at the Jet Propulsion Laboratory under a contract with NASA. It clarifies that references to specific commercial products or services do not imply endorsement by the U.S. Government or the Jet Propulsion Laboratory.
Overall, this report presents a significant advancement in thruster technology, highlighting the potential for improved spacecraft maneuverability and efficiency. The innovative design and operational capabilities of the hydrazine thruster could play a vital role in future space missions, particularly those requiring precise attitude control and minimal resource consumption.
