OLAF: a Swarm of Microsatellites for Active Debris Removal by Space-based Laser Ablation

Small debris objects (1 mm–10 cm) pose a considerable risk to active spacecraft, potentially causing mission-critical damage as they can reach relative impact velocities of 15 km/s in LEO. ESA’s latest Space Environment Report estimates more than 130 million objects in this size range residing in LEO, the majority of which cannot be tracked by current ground-based space surveillance systems due to their small size.

OLAF (Orbital Laser Ablation Formation) is a proposed mission concept that employs a swarm of 11 microsatellites (1 chief and 10 chasers) working together to detect, track, and remove small debris fragments from low Earth orbits using space-based laser ablation. The chief spacecraft is equipped with a wide-FOV 40-cm telescope for debris detection and coarse trajectory estimation. The chasers carry high-resolution, narrow-FOV 60-cm telescopes for precision tracking. In addition, the chasers are equipped with high-power 5.6 kW pulsed Nd:YAG lasers operating at 355 nm, whose combined fluence at the target exceeds the ablation threshold, thus effectively decelerating approaching debris objects and reducing their orbital lifetime. Laser-debris interactions were simulated for various impact geometries, yielding significant lifetime reductions for fragments approaching from altitude differences of up to 10 km and azimuth angle differences of up to 40 degrees.

Funded under ESA NAVISP Element 1, the project focused on the autonomous navigation and formation-flying aspects of the mission. The swarm activities are coordinated by the chief spacecraft, which receives GNSS-based PNT and visual-based navigation data from the chasers via an inter-satellite link, and processes them using a sensor fusion algorithm to compute relative state knowledge of the swarm. An MPC-based law is used for formation control. The mission’s commercialization potential was identified, with costs per debris deorbited of order 100 EUR. Finally, an innovation roadmap identified the necessary activities to bring the technologies to operational maturity.