The way a laser broom works is imparting an extremely miniscule bit of momentum every time the object is in line of sight of the laser. Over time you lower its orbit enough for atmospheric drag to take over. For small debris, like baseball sized chunks of insulation, it takes months to deorbit the objects. For something the size of a satellite it would take an order of magnitude longer than the life expectancy of the satellite, and that's assuming it does no station-keeping.
Laser brooms are great because they can deorbit a lot of debris in parallel, which is great if your goal is to slowly clean up an orbit. They are pretty much the worst option for deorbiting a specific object quickly which is a hard requirement for any anti-satellite weapon.
Makes sense but are there actually limits that prevent the scaling? IE instead of a single laser broom I build 50 near a solar/nuclear plant and use the surplus energy. Usually they all deorbit different objects but I could choose to aim them all at the same object.
I don't see much of a limit to scale. Satellites can only dissipate so much heat so you don't even have to deorbit it to be successful, you just need impart enough energy to overheat the satellite or disable key parts.
A single broom for debris clearing is an immense project - likely $500 million to $1 billion to construct. It is basically a big observatory telescope with a gigantic high power laser - it is large, fragile, and completely immobile. That's for slowly cleaning up an orbit, to scale up to a weapons system you'd need a system equivalent to building tens of thousands of them.
You're not building a weapon system with surplus energy. Energy costs are actually pretty negligible - with 0.01% electric to kinetic efficiency it's only about 7 million dollars worth to bring down a 1000 kg satellite. The issue is the equipment. To deorbit that satellite in a year, you would need to on average be pumping 7.8 gigawatts of electricity into the system. If you put literally all of the US's electricity production into it, you could deorbit that single satellite in 2.4 days. And note that is if you could constantly keep the satellite in field of view, realistically only a small percentage of a satellite's orbit will be even under the best of circumstances, and many orbits won't be in view at all.
Yeah, there's nothing physically stopping someone from building such a system, but you're talking about putting basically all of a large nation state's GDP for decades into one weapon system that, in the best case scenario, is going to do an extremely minute amount of damage and realistically would be destroyed long before it could accomplish anything.
Disabling a satellite poses different technical challenges. For momentum transfer, so long as you're hitting the object you're good, to target critical systems would require far greater precision, and dumping heat faster than the satellite can dissipate it would require even higher instantaneous power. Remember the satellite is only very briefly in view. While this is almost certainly more feasible than a weapon that works by deorbiting, it is still very difficult. Laser weapons for disabling and destroying aircraft and airborne munitions, which is an inherently easier task, is an active field of research that many billions of dollars have been dumped into over the years, with no system yet being demonstrated as effective. Satellites are just faster moving, more distant targets for such systems.
ASAT missiles might be too mundane for the megalomaniac Bond villain, but they are an immensely more practical solution to the problem.
