Marshall Space Flight Center- Solar Sail GNC and Mission Design
June 6 2022 – August 12, 2022
Goals of your project/s:
I was part of the Guidance, Navigation, and Control (GNC) Team for the Near-Earth Asteroid (NEA) Scout solar sail project. The goal of the project is to demonstrate the capabilities of solar sail propulsion for use in future missions and to travel to and image a near-Earth asteroid. I supported the GNC Team in one of the last stages of the project before launch.
Describe what you did during the internship:
I performed Monte Carlo simulations of RCS thruster dispersions for two particular scenarios. One scenario simulated how slight misestimates of the exact location of the spacecraft’s center of gravity could cause errors in our torque magnitude estimates, and the second scenario simulated how slight misestimates in the exact direction of the thrust forces could cause errors in our torque and thrust estimates. The purpose was to determine how far off our estimates for the thrusters’ performance could potentially be and what thrust variations to anticipate before flight. I also determined keep-out-zone (KOZ) angles as a function of range for the star tracker onboard NEA Scout and helped write a flight rule for necessary minimum KOZ angles depending on range.
Did you achieve your goals? What were the results?:
I achieved the goals of the tasks I was assigned, with the exception of part of one of the simulations. The results of the simulations I performed confirmed our expectations for the potential dispersions in the thrust forces, which will be helpful for knowing what performance to expect from the thrusters. Half of the results from one of the simulations were quite different from other half of the results, and I ran out of time before I could determine if that was due to simply a mistake in the code or something more. The minimum KOZ angles needed to ensure proper performance of the star tracker ended up much smaller than we had initially expected, which means that much less reorientation of NEA Scout will be required to keep the star tracker functioning correctly. The spacecraft launches very soon, so it should only be a few weeks before it is on its way to performing its mission.
Describe positive lessons learned:
I learned a lot of general things about what it would be like day-to-day to work as an engineer at NASA, including learning a lot of acronyms. I learned that there are different types of ‘simulations’ and how simulations can be useful to engineers. I learned about the small-scale preparations that are done right before the start of a spacecraft’s mission. I met a lot of capable and helpful people who I would be happy to work with in the future. I also learned many pros and cons of working remotely; being remote requires a great deal more scheduling, can speed up and slow down some communication, and can save you a lot of expense and hassle.
Describe negative lessons learned:
I learned that even NASA can sometimes have struggles with technology. There was a lot of waiting and some troubleshooting involved with setting up my laptop and installing some software on it. It was frustrating at the time, but these issues eventually got resolved and did not show up again. I also learned that parts of the experience of having an internship can be lost by being remote instead of on-site. I think that I may have missed out on a lot of potential interactions and conversations with other interns and engineers by never being there in person.