[jcims]

I’ve been wondering lately if you could use little puffs of gas fired from a satellite at very high velocity to impact smaller debris and take some kinetic energy from it.

It sounds ridiculous but v^2 scales quickly and if you can achieve anything close to the exhaust velocity from ion thrusters combined with retrograde orbit you can start knocking on the door of 100km/s impact velocity. That’s ~5J per microgram.

Obviously a tremendous number of challenges (puff coherency over great distances, accuracy over same, stationkeeping, etc) but interesting to me nonetheless.

[rwesterdahl]

Right now we are primarily focused on building something to address the big stuff because of the possibility of breaking up into thousands of smaller debris. At some point the smaller debris will need to be addressed, in which case its possible something like this would work. That being said Space Lasers may also be a contender, but that comes with the caveat of being classified as a weapon. Either way it will be interesting to see different ideas come to fruition over time, both from our playbook, and from others!

[switch_]

Lasers were my first thought since it requires so much energy to change orbits in order to interact more directly with the debris. What properties are considered when classifying lasers as weapons? Would a lower power laser still be feasible for small debris?

[jcims]

I can think of only two applicable mechanisms of action with lasers, there could be more:

1 - Radiation pressure. This is just momentum exchange between the object and incoming photons. It very clearly has a force and is partly responsible for sending dead spacecraft into a tumbling motion. The challenge with radiation pressure is that it has an extremely small effect relative to the input power, in the range of micronewtons per kilowatt. Low power lasers that would not be considered 'possible weapons' would be effective but over very long timescales.

2 - Ablative reaction. When you ramp the energy level enough to cook off layers of material, the ejection of the particles has a reaction effect that pushes the object in the opposite direction. Fiber laser engravers (YouTube it if you're not familiar) use this as the mechanism for material removal. These lasers have relatively low average power (say 20W-100W), but its delivered in very short high-power pulses necessary to heat just the skin of the material. Because of that, the instantaneous power levels might be 100-500kW, clearly 'weapons' class. It wouldn't have any effect on ground targets but could easily be employed in anti-satellite operations.

[dandelany]

I have thought about this too, retrograde orbit buys you a lot of “free” energy for deorbiting things going in the other direction. The “puff coherency” problem as you succinctly put it seems like the hardest problem. Maybe if the gas is ionized, you could use another spacecraft[s] to generate a magnetic field that could trap the cloud long enough to get the “puffer” craft out of the way before impact.