The SOC-i mission will carry an advanced guidance, navigation and control (GNC) payload capable of reorienting the spacecraft while satisfying multiple pointing constraints. SOC-i will also carry an Earth imaging camera, enabling it to take pictures of specified ground locations requiring stringent pointing.
The mission will operate in space for 6 months, while supported by a UW ground station being developed in the Aerospace Engineering Research Building. It is a stated goal of the mission to be completely open-source, maintain code on our team's GitHub page .
All subsystems are being developed to support the primary science objectives, while also serving to define an AACT-standard 3U bus for future missions.
The experimental GNC system is capable of reorienting the spacecraft while guaranteeing hard pointing constraints and in a time-optimal fashion. In the figure below, the green cone represents a navigation sensor's field of view, while the red cone represents the camera's field of view. Reorientation maneuvers must be executed such that (i) the sun vector remains inside the green cone, (ii) the sun vecotr simultaneously remains outside the red cone, (iii) actuator limits are not violated and (iv) the reorientation takes minimal time. The satellite must compute these solutions on-board and in real-time, without any pre-loaded solutions or ground intervention.
This payload leverages previous work done at the UW in this area. In particular, we adapt methods from (Kim et al, 2010) and (Lee and Mesbahi, 2013) to formulate the problem.
Solutions are obtained in real-time using the ECOS solver running on the main flight computer. Our implementation is an on-going process, but will use elements of optimal control theory or Successive Convexification .
See the open source GNC code based in Matlab/Simulink.
Read about our experimental GNC system validation
See our publications to read more on this topic.
We are currently performing trade studies on candidate imaging systems sufficient for our mission's needs.