We propose the design, development, and high-fidelity validation of the autonomous nanosatellite swarming subsystem (ANS). ANS is an integrated miniaturized dynamics, guidance, navigation, and control…

The Leland Stanford Junior University (Stanford University) was awarded a $1,763,822 cooperative agreement (Contract #80NSSC18M0058) by the National Aeronautics and Space Administration (NASA) to design, develop, and validate the Autonomous Nanosatellite Swarming Subsystem (ANS). ANS is an integrated miniaturized dynamics, guidance, navigation, and control unit that enables multiple nanosatellites to act together as a single large spacecraft through precision relative navigation and low-thrust control. This work is intended to support future applications in planetary/Earth remote sensing, astronomy/astrophysics, space exploration, and situational awareness. The contract has no set-aside designation, and the anticipated completion date is December 31, 2025. This effort is being conducted in partnership with NASA Ames Research Center and leverages research and development at Stanford's Space Rendezvous Laboratory.

We propose the design, development, and high-fidelity validation of the autonomous nanosatellite swarming subsystem (ANS). ANS is an integrated miniaturized dynamics, guidance, navigation, and control unit based on commercial-off-the-shelf avionics which is distributed and deployed on a cluster of cooperative nanosatellites or swarm to enable future applications in planetary/earth remote sensing, astronomy/astrophysics, space exploration and situational awareness. ANS allows multiple nanosatellites to act together as a single large spacecraft thanks to precision centimeter-level radio-frequency/optical relative navigation and micro-newton lowthrust control. As a result, the ANS-equipped nanosatellites can fuse passive images of a space resident object or remote sensing target, simultaneously taken from multiple viewpoints, to achieve stereo-vision capabilities. These include the real-time on-orbit recovery of the three-dimensional model, inertia properties, and gravity field for small celestial objects. The potential new applications are manifold and ANS is designed to support the broadest range of operational scenarios, inter-satellite distances and orbit regimes, such as swarm deployments from a mothership spacecraft, quick forced-motion control reconfigurations, or long-term passively safe and stable relative orbits in close proximity with minimal actuation. All this is enabled by the fusion of major advances to the state-of-theart in relative astrodynamics, vision- and radio-frequency navigation, and low-thrust control. The backbone of ANS is a new accurate and efficient closed-form propagation of the satellite relative motion in the presence of all perturbations of interest based on relative orbit elements. The analytical nature of this novel theory allows the design and coordination of swarms with exceptional long-term properties. The minimum propellant optimal control problem can be translated into a minimum length path-planning problem in the new state variables. This enables the derivation of closed-form solutions for impulsive and extended maneuvers and the enforcement of user-defined constraints in both the state and control input parameters. Uncertainties which affect the dynamics modeling are accounted for in the reduced-dynamics estimation process through state-augmentation techniques and exponentially correlated gauss- markov processes. For the first time, we propose the fusion of radio-frequency carrier-phase and optical observables to robustly determine the carrier-phase integer ambiguities and consequently exploit range measurements with millimeter-level noise for relative navigation. ANS fuses diverse raw measurements provided by a customized nanosatellite sensor suit including cameras for vision and infrared navigation, and high-frequency RF links for communication and ranging. Even in the absence of RF links, ANS can navigate the swarm through angles-only measurements obtained from centroids of the CO-orbiting vehicles seen in the individual cameras field of view. To this end, a non-linear filter formulation is proposed to improve the observability of the dynamics system in the absence of range measurements. ANS leverages new algorithms, hardware and software under development and evaluation at the stanford's space rendezvous laboratory (slab). Slab features custom high-fidelity virtual reality devices and a 7DOF robotic testbed for the real-time stimulation of ANS in closed-loop under realistic illumination conditions. Key partner of the proposed effort will be NASA ARC, which is considering the on-orbit demonstration of ANS in the frame of the starling swarm technology demonstration missions