In recent years, the popularity of CubeSatellites, or CubeSats, for space missions has grown exponentially. They provide a miniature, standardized form factor and prioritize the use of commercial-off-the-shelf (COTS) components that reduce the size, weight, and power of space missions. Their compact size and cost-effectiveness are well suited to demonstrate and raise the technology readiness of smaller and higher-performing payloads. However, the increasing pointing requirements that come with these payloads and lower overall satellite mass means that jitter caused by moving or vibrating parts in CubeSats is a fundamental limit in their performance. Typical methods of characterizing jitter involve complex finite element methods, and measuring jitter requires high costs in equipment and laboratory setup, as well as significant modification in the mass and inertial properties of the subject. This is due to the use of adapting plates on dynamometers and alternatively, jitter measurements made in-situ do not allow for modification of the satellite nor its components to achieve more optimal jitter characteristics. This makes in-situ measurements useful as a method of evaluation since there are no external damping effects. But, because the satellite is in space, cannot be a part of the validation process. In this paper, we describe a novel method of characterizing jitter for small satellite systems that is low-cost, simple, and minimally modifies the subject’s mass distribution. The metrology instrument comprises of a COTS fiber-coupled laser source, a small mirror that is rigidly mounted to the satellite structure, and a lateral effect position sensing detector. The system samples at a frequency of 1kHz and can measure jitter as low as 0.154 arcseconds over measurement baselines of 1 meter. We also use a procedure that incrementally analyzes vibrating sources to establish causal relationships between sources and the vibrating frequency modes they create. Results from power spectral density plots show that this method can detect fundamental and higher-order vibrating modes in a fully integrated 6U spacecraft. The analysis is focused on attributing the causation of these modes to vibrating sources (such as reaction wheels and the cryocooler), verifying these correlations, and determining their pointing error contribution. We expect that this metrology system can serve to not only detect and characterize jitter in fully integrated small satellites and imaging systems from vibration sources but also verify vibrating satellite bus component performance like those from reaction wheels.

Chase Urasaki is an M.S. candidate in Electrical Engineering at the University of Hawaiʻi at Mānoa. He obtained his B.S. in Astrophysics and B.S. in Mathematics also from the University of Hawaiʻi at Mānoa in 2019. His current research focuses on the CubeSats and their applications in astronomical science and observations. More broadly, his interests lie at the intersection of engineering and astronomy.