Space is silent. No air, no sound. This must have seemed strange on February 10, 2009, when the satellites “Kosmos-2251” and “Iridium 33” collided, shattering the spacecraft into more than 2,000 pieces of debris. Now, each of these pieces presents a new risk of collision to our satellites in low Earth orbit.

An example collision avoidance scenario between two close-orbiting satellites.

The potential to collide with other satellites or debris is a real and growing concern. As a result, collision detection and avoidance are becoming a critical aspect of satellite operations.

We have worked on new collision avoidance algorithms and strategies for several different projects, including the Prisma formation flying mission which was launched in 2010.

Some of our work in this area was just published in the Journal of Aerospace Information Systems. The paper is “Avoidance Maneuver Planning Incorporating Station-Keeping Constraints and Automatic Relaxation”. You can find it here: http://arc.aiaa.org/toc/jais/10/6

The paper discusses different ways to model the time-varying avoidance region that represents the predicted path of another satellite, and methods for computing minimum-fuel maneuvers that satisfy both the avoidance constraints and station-keeping constraints for the mission. The details may be complex, but the message is simple: “Move it or lose it!”