Follow the mission and the propulsion requirement follows. Servicing or removing another satellite means flying very close to an object that may be tumbling, uncooperative, or fragile. That demands not raw thrust but finesse, the ability to make small, precisely modulated maneuvers in close proximity without overshooting or colliding.
Astroscale's grant US11286061B2 (inventors Michael Reitman, Arnon Spitzer, Arie Halsband, and Ofir Azriel), classified in B64G 1/1078 (servicing spacecraft) with B64G 1/242 (attitude control), B64G 1/646, and B64G 4/00 (on-orbit operations), claims a service satellite built around variable thruster control. The B64G 4/00 code, support and inspection of spacecraft in orbit, names the business directly.
The mechanism is throttleable, finely controlled thrust married to close-proximity attitude control. The variable in variable thruster control is doing the work: the satellite needs to dial thrust up and down smoothly through the approach and capture phases, which is a very different requirement from a satellite that just needs to station-keep.
For a private servicing company, this kind of grant is a clear public window into capability and intent. It tells you Astroscale considered the proximity-operations propulsion and control architecture to be a defensible core asset, exactly what you would expect from a company whose whole thesis is operating around other people's spacecraft.
The standing caution for any proximity-ops claim: rendezvous and capture are famously unforgiving, and a patent on the control approach is not a demonstrated docking. The document tells you how Astroscale intended to fly the hardest part of the mission. The on-orbit demonstrations, not the claim set, are where that intent gets validated.