High-Emissivity CVD Dendritic Rhenium Coatings for NEP Radiator Panels

Status: Completed

Start Date: 2023-08-03

End Date: 2024-02-02

Description:

Nuclear-electric propulsion (NEP) provides a means of significantly reducing mission durations for space exploration. NEP is able to provide substantially greater propulsion efficiency over chemical propulsion systems. The advantage of NEP is that it requires little propellant, is not reliant on solar proximity/orientation, and can provide thrust for extended periods of time. Further, NEP can be combined with chemical propulsion to provide high specific impulse (Isp)/low-thrust and low-Isp/high-thrust propulsion respectively, depending on mission and spacecraft requirements. One of the largest obstacles to overcome for more efficient space travel is the total vehicle mass. NEP development is dependent on the development of several key technology areas, one of which is the primary heat rejection subsystem, which requires a highly emissive radiator. In a NEP vehicle, the radiator will account for a significant portion of the total vehicle mass. Improved radiator panels are needed, allowing for either a reduction in the overall vehicle mass as the panel size is reduced, or a more powerful propulsion system as waste heat is more effectively managed. The current state-of-the-art space radiator material system uses carbon/carbon (C/C) composite panels that are built around or bonded to titanium alloy heat pipes. To increase the emissivity of the radiator with minimal effect on the overall weight, Ultramet proposes to apply a thin high-emissivity coating to the C/C panels. In this project, Ultramet will use chemical vapor deposition (CVD) to deposit a thin, highly emissive dendritic rhenium coating on carbon and titanium substrates to demonstrate feasibility. The emissivity and ion bombardment survivability of the dendritic coating applied to carbon and titanium substrates will be characterized through testing.

Benefits:

Enabling human Earth‐to‐Mars round trip mission durations of less than 750 days is a key goal for NASA. Nuclear power provides the means of achieving this goal, but operating a nuclear reactor in space require the reactor to be smaller and more compact than ground-based systems. Waste heat must be rejected into space through radiators. The proposed radiator panels will provide a lightweight, high-efficiency, high thermal conductivity advancement in heat removal for cislunar, Mars, and outer solar system missions, both crewed and robotic.

The proposed technology will be ideal for existing and new electric propulsion systems used for spacecraft station-keeping and attitude control of commercial and military spacecraft. Terrestrial applications include plasma processing for a wide range of product manufacturing and services, pulsed power devices, and material characterization facilities utilizing high electron currents.

Lead Organization: Ultramet