CubeSats are small, modular, and increasingly capable spacecrafts that have changed how we think about space. And yet, while lower earth orbit satellites bring flexibility and affordability, they also introduce new challenges, especially when it comes to coordinating tasks across a constellation. This is where formation flying becomes essential.
Formation flying allows a cluster of small satellites to operate as if they were a single, coordinated system. Rather than building one complex satellite, mission designers can deploy multiple simpler ones and assign each a specialized role – one for imaging, one for infrared sensing, another for data relay. This modular approach makes missions more scalable, more robust, and often far more cost-effective. But with that modularity comes the need for precision.
In practice, it means controlling the relative distances and orientations of satellites flying in the same orbit. It means making sure that a LEO satellite launched six months after the rest of the constellation can still join the formation and play its part. And it means doing all this with minimal fuel and delta-V, limited communication bandwidth, and tight operational constraints.
At Terma, we added the feature to the ORBIT Flight-Dynamics System with exactly these challenges in mind. CubeSats and LEO satellites don’t have the luxury of onboard supercomputers or large propulsion systems, so our system runs entirely on the ground. That way, operators don’t need to upgrade their hardware or load additional software onto their satellites. Instead, they simply define the formation, select a leader satellite, and let ORBIT calculate how the others should move to fall into place.
We use a strategy known as Leader-Follower. One satellite, typically the one already flying a stable orbit, acts as the reference point. The others are commanded to maintain a fixed distance relative to it. Whether they need to be ten kilometers behind, twenty kilometers above, or some combination of both, ORBIT computes the maneuvers needed to reach and maintain that geometry. Even if they start far apart, the system plans a safe sequence of burns to bring them into formation without risking collision or exceeding thruster limitations.
One of the most common concerns among small satellite operators is whether formation flying requires special onboard systems. The short answer is no. Our system was designed to operate from the ground specifically so that missions with legacy CubeSats or those launching on tight timelines can still take advantage of coordinated flight. As long as the satellites can receive commands and execute small maneuvers, they can fly in formation.
The benefits are clear: You get better coverage. You can mix and match capabilities. You reduce mission risk because one satellite failure doesn’t doom the whole system. And perhaps most importantly, you extend the value of your platform. Need to upgrade your imaging capability next year? Just launch a new LEO satellite and insert it into the existing formation.
CubeSats have opened the door to space for universities, startups, and nations around the world. Formation flying is how we turn that access into capability. At Terma, we’re making sure that even the smallest satellites can operate with big mission ambition.