Autonomous Scheduling of Agile Spacecraft Constellations with Delay Tolerant Networking for Reactive Imaging
Presenting Author: Sreeja Nag
Organization: NASA Ames Research Center / BAERI
Co-Author(s): Alan Li, Vinay Ravindra, Marc Sanchez Net, Kar-Ming Cheung, Rod Lammers, Brian Bledsoe
Constellations are being recognized as important Earth Observation solutions to increase measurement samples over multiple spatio- temporal-angular vantage points. Larger numbers of smaller spacecraft also minimize launch and operational risks, and maximize evolution with time and technology. Small spacecraft (baselined at 20 kg for this presentation) have the capability to host imager payloads and can slew to capture images within short notice, given the precise attitude control systems emerging in the commercial market. When combined with appropriate software, this can significantly increase response rate, revisit time and coverage. In prior work, we have demonstrated an algorithmic framework that combines orbital mechanics, attitude control and scheduling optimization to plan the time-varying, full-body orientation of agile, small spacecraft in a constellation, such that they maximize observations for given imaging requirements and spacecraft specifications. The proposed schedule optimization would run at the ground station autonomously, and the resultant schedules uplinked to the spacecraft for execution. The algorithm is generalizable over small steerable spacecraft, control capability, sensor specs and regions of interest. In this project, we have modified the algorithm to run onboard small spacecraft, such that the constellation can make time-sensitive decisions to slew and capture images autonomously, without ground control. We have developed a communication module based on Delay/Disruption Tolerant Networking for onboard data management and routing among the satellites, which will work in conjunction with the other modules to optimize the schedule of agile communication and steering. We then apply the developed software (for both, ground-based and onboard autonomy) on representative constellations to simulate targeted measurements of multiple phenomena in a scenario for episodic precipitation events and subsequent floods, with varying requirements for data latency and reaction time. The autonomous command and control efficiency of our agile algorithm, compared to static sensors, will be quantified with a simplified observing system simulation.
NOTES: This is a NASA New Investigator Program project. ESTO sponsors 2 of 3 years of the project duration.