Starling's successful mission demonstrated the potential of constellations of satellites for autonomous navigation and operations, paving the way for advanced space traffic coordination. Credit: Blue Canyon Technologies/NASA
The Sterling constellation has completed its primary mission, demonstrating a breakthrough in autonomous satellite operations and navigation, setting the stage for future collaborative space traffic management. SpaceX.
After 10 months in orbit, the Stirling constellation has successfully accomplished the primary objectives of its primary mission and demonstrated great promise in constellation capability.
Satellite constellations may one day be used for deep space exploration: autonomous spacecraft networks would be able to navigate autonomously, manage scientific experiments, and perform operations to respond to environmental changes without the burden of communication latency between the constellation and Earth.
“The success of Sterling's first mission represents a milestone in the development of autonomous networks of small spacecraft.” National Aeronautics and Space Administration (NASA)Members of a team working with NASA's Small Spacecraft Technology Program at NASA's Ames Research Center in Silicon Valley, California. “The team has been very successful in meeting its goals and adapting to the challenges.”
Share your work
The Distributed Spacecraft Autonomy (DSA) experiment aboard Stirling demonstrated the ability of a swarm of spacecraft to optimize data collection across the swarm. CubeSats analyzed Earth's ionosphere by identifying phenomena of interest and reaching agreement among each satellite on an approach for analysis.
By sharing observation tasks across the swarm, each spacecraft can “share the load” and observe different data or work together to perform deeper analysis, reducing the workload for humans and allowing the spacecraft to continue operating without the need to send new commands from the Ground.
The success of this experiment means that Sterling is the first spacecraft swarm to autonomously distribute information and operational data between spacecraft and develop plans to work more efficiently, and it is the first demonstration of a fully distributed on-board reasoning system that can respond rapidly to changing scientific observations.
The four CubeSate spacecraft that make up the Stirling constellation operated successfully autonomously and achieved all primary mission objectives. Credit: NASA
Communication beyond the crowd
A swarm of spacecraft needs a network to communicate with each other, and the Mobile Ad Hoc Network (MANET) experiment automatically built a network in space to allow the swarm to relay commands and transfer data between each other and the ground, and to cooperate and share information about other experiments.
The team successfully achieved all of the objectives of the MANET experiment, including demonstrating routing commands and data to one of the spacecraft that was having trouble communicating between space and ground – a valuable benefit of a cooperative constellation of spacecraft.
“The success of the MANET is a testament to the robustness of the swarm,” said Howard Cannon, Sterling project manager at NASA Ames Research Center. “For example, when the radio went down on one of the swarm's spacecraft, we 'sideloaded' the spacecraft from the other direction, sending commands, software updates, and other critical information to the spacecraft from another swarm member.”
Autonomous Crowd Navigation
Navigating and maneuvering in relation to each other and to the planet is a key part of forming a constellation. The Starling Formation-Flying Optical Experiment (StarFOX) uses a star tracker to recognize fellow spacecraft, other moons, or space debris from the background stars and estimate each spacecraft's position and velocity.
The experiment marks the first public demonstration of this type of swarm navigation, including the ability to simultaneously track multiple members of a swarm and share observations between spacecraft. Accuracy when determining the trajectory of each swarm member.
Near the end of mission operations, the swarm was maneuvered into a passive safety ellipse, and in this formation the StarFOX team achieved a groundbreaking milestone, demonstrating the ability to autonomously estimate the swarm's orbit using only inter-satellite measurements from the spacecraft's star trackers.
Managing herd movements
The ability to plan and execute operations with minimal human intervention is a key factor in developing large satellite constellations. Autonomously managing the trajectories and operations of hundreds or thousands of spacecraft saves time and reduces complexity.
The ROMEO (Reconfiguration and Orbit Maintenance Experiments Onboard) system will test the planning and execution of onboard operations by estimating the spacecraft's trajectory and planning maneuvers to a new desired orbit.
The experiment team successfully demonstrated the system's ability to determine and plan orbital changes, and is working to refine the system to reduce propellant use and demonstrate the execution of the maneuver. The team will continue to adapt and develop the system during Stirling's mission extension.
In a flock
Now that Sterling's primary mission objectives are complete, the team is embarking on a mission extension called Sterling 1.5, which will test space traffic coordination with SpaceX's Starlink constellation, which also includes autonomous capabilities. The project will explore how constellations operated by different users can share information through a ground hub to avoid potential collisions.
“The partnership between Sterling and SpaceX is the next step in operating a large spacecraft network and understanding how two autonomously piloted systems can safely operate in close proximity to each other. As the number of operational spacecraft grows every year, we must learn how to manage orbital traffic,” Hunter said.
NASA's Small Spacecraft Technology Program, based in Ames and housed within NASA's Space Technology Mission Directorate (STMD), funds and manages the Sterling mission. Blue Canyon Technologies designed and built the spacecraft bus and provides operational support for the mission. Rocket Lab USA, Inc. provides launch and integration services. Partners supporting Sterling's payload experiments include Stanford University's Space Rendezvous Lab in Stanford, California, York Space Systems (formerly Emergent Space Technologies) in Denver, Colorado, CesiumAstro in Austin, Texas, and L3Harris Technologies, Inc. in Melbourne, Florida. Financial support for the DSA experiment was provided by NASA's Game Changing Development program within STMD. Partners supporting Starling's mission extension include SpaceX, Hawthorne, California, NASA's Conjunction Assessment Risk Analysis (CARA) program, and the Department of Commerce. SpaceX manages the Starlink constellation of satellites and the collision avoidance ground system.
