Dynamic instabilities imparted by CubeSat propulsion

Abstract

As the role of CubeSats evolves to include more challenging and complex missions in addition to technology demonstrations, the demand for agility have increased. As the technology improves and gains flight heritage, CubeSats are being deployed to accomplish more difficult missions including, but not limited to, large constellations and missions beyond Low Earth Orbit (LEO). To perform missions like station keeping for constellations, and to move beyond LEO, CubeSat developers are increasingly integrating propulsion into the design of their CubeSats. In addition, more complex payloads and communication systems require more power generation, which leads to larger deployed solar arrays. Meanwhile, the limiting factor for the CubeSat remains the size and weight constraints of the containerized launch deployers. In order to meet these constraints, the solar array design has to trade stiffness and strength for size. In this work, we investigate whether designs that use a combination of propulsion and solar arrays stress the dynamics of the solar panels and the hinges that hold them in place. Our approach uses SimXpert to perform dynamic simulations on CubeSat models, both 3U and 6U, with deployable solar panels and propulsion forces. By default, SimXpert treats every part as a rigid body and stress is not calculated. By doing a modal analysis of the panels in Nastran and importing the results into SimXpert, stress on the panels can be tracked during propulsive maneuvers. We determine that Margin of Safety (MoS) for the solar panels analyzed is over 100 when combined with three different COTS propulsion units. We also show the movement induced on the panels from propulsion can cause errors in body attitude ranging from 0.04 to 90 degrees. The worst case showed a difference becoming one degree in five seconds before growing exponentially to 90 degrees in 30 seconds.