Blog Articles

Celebrating 10 Years of Autonomous Formation Flying with Smaller Satellite Technology Enables Multi-Satellite Applications – Part 1

By Dr. Robert E. Zee

can x 4 and 5

SFL is celebrating 10 years of autonomous formation flying with smaller satellites. On June 30, 2014, we launched CanX-4 and CanX-5, the first nanosatellites to accomplish precise, autonomous formation flight with centimeter-level knowledge and sub-meter level control accuracy in low Earth orbit. One major beneficial outcome of this highly successful mission was to present the world with a critical space-proven technology now available at low cost from SFL.

Our formation flying technology has enabled new business models and commercial exploitation not previously possible due to cost.

Autonomous formation flying makes it possible for multiple satellites to work together and, in some cases, effectively perform functions of a larger satellite, or perform missions that cannot be accomplished with a single satellite. This is particularly important in the NewSpace era when launching a constellation of smaller satellites can offer a significant cost advantage over developing one traditional large satellite.

Some remote sensing and geolocation applications become viable when two, three or more satellites are flown in precise orbital configurations. Such multi-satellite applications are typically not financially viable with satellites developed using traditional “big space” approaches.

Autonomous formation flying means the satellites are orbiting in a constellation with their relative positions and trajectories precisely maintained without assistance from ground-based commands. Autonomy refers to the fact that onboard hardware and software allow independent action and enable the satellites to communicate with each other to keep their positioning exact.

One of the uses of formation flight is in geolocation services. This involves three or more satellites receiving radio frequency (RF) signals from transmission sources on the ground and using triangulation to precisely calculate their locations in three dimensions. The accuracy of the location calculation depends on how precisely the separation of the satellites is known and controlled.

HawkEye 360 of Herndon, Va., is the first to develop a commercial business around this application. SFL provided the buses and satellite integration services for its first three Pathfinder microsatellites. As a result of the tremendous success of Pathfinder, we were awarded the contract for development of the company’s commercial (operational) constellation utilizing next-generation satellites. 

As of mid-2024, HawkEye 360 has launched 27 RF geolocation microsatellites in three-spacecraft clusters developed by SFL. Currently, we are designing, assembling, and integrating Clusters 12 at our facility in Toronto, while HawkEye 360 is integrating Clusters 10, 11, and 13 at its own plant in Virginia under our Flex Production Program.

Another formation-flying mission under development now at SFL is the three-satellite Gray Jay formation flying constellation for Defence Research and Development Canada. Built on our space-proven and scalable DEFIANT microsatellite platform, the Gray Jay surveillance demonstration mission will carry multiple sensors for timely detection and identification of surface and airborne targets in Canada’s expansive Arctic region. Close formation of the satellites will ensure accurate identification of targets and precise location of their positions.

A geospatial application enabled by autonomous formation flying is sparse aperture sensing. In this application, a cluster of satellites equipped with small sensors capture data that is then combined to provide an effective larger aperture than the individual satellites in the cluster can independently carry.

What makes formation flying possible? Read our next blog to learn more about the “complex choreography” between hardware systems and software algorithms that makes autonomous formation flight a reality. Or you can check out a feature article on this topic published in a geospatial surveying and mapping magazine called xyHt.