About the Internship (Jun 5 – Aug 12, 2016)
NASA Marshall Space Flight Center is sponsoring efforts to develop technology for integrating a high-performance, low-hazard monopropellant into Cubesat platforms. The program focuses on a “green” monopropellant GPROP as an alternative to the widely used Hydrazine monopropellant. Being markedly less hazardous than Hydrazine, GPROP is attractive due to easier ground processing and storability. While research has been conducted on the characterization of the propellant itself, to date, a fully integrated propulsion system has yet to be tested. NASA is coordinating their monopropellant efforts with the United States Air Force to develop a 100 mN 1U Cubesat module that will utilize the GPROP monopropellant.
The culmination of previous years of characterization research is to integrate the GPROP propellant into a fully integrated propulsion system. A summer 2016 Propulsion Academy group was tasked with designing this system to scale for use in CubeSat platforms. Acting as a proof-of-concept to hopefully further the TRL (technology readiness level) a hot-fire test of this system will demonstrate the feasibility of “green” monopropellant use in future spacecraft propulsion systems.
Early in the project analysis ranging from thermal to structural to fluid dynamics had to be conducted. Given a set design for the thruster, components had to be designed around it that would allow for integration into the CubeSat frame. Leading up to this final test, many verifcation tests had to be conducted. With the module designed and fabricated, each major component had to be tested. This included burst testing the propellant tanks, power and thermal verification for the thruster heater and control board, pressure checking feed lines and panels, and lastly conducting an all-up thermal verification test of the system without propellant. After these tests were completed, a test-readiness-review would assess the readiness of the team and test facilities for the hot-fire.
Results and Conclusions
To summarize, the propellant tanksheld, the thermal management system kept the propellant from overheating in the tank, the heater and controller maintained the breakdown temperature, the pressurization and feed systems did not leak, and most importantly, the system successfully underwent a hot-fire test. Although the GPROP propellant has been fired numerous times, this was the first time it had ever been integrated into CubeSat scale module and successfully fired. This proved to be a major first step in possibly replacing Hydrazine for in-space monopropellant propulsion systems.
If I learned anything from this project it was that communication is key. Working efficiently as a team was the most vital aspect of this project. The team I worked with made everyday more interesting than the last, especially on our last day of the summer when made some fire and smoke. The successful hot-fire test can be contributed solely to the ability of each team member to not only carry a portion of the project, but to keep everyone informed its status. Besides learning a great deal about chemical propulsion systems, getting experience in just about every facet of research engineering, and learning plenty of NASA history, this project taught me that the success of a team lies in the partnership of each individual member more than anything.