[Tommstein]

> Also, if it's not big enough to monitor it can disappear. Radar makes it hard to track anything that's not huge and actively transmitting.

I don't know about that:

"Since 1990, the Goldstone Orbital Debris Radar has collected orbital debris data for debris as small as about 2 mm in LEO for the NASA ODPO. . . . . The Goldstone Orbital Debris Radar is an extremely sensitive sensor capable of detecting a 3-mm metallic sphere at 1000 km, which makes it an incredibly useful tool in the characterization of the sub-centimeter-sized debris population." - https://orbitaldebris.jsc.nasa.gov/measurements/radar.html

[bagels]

Mechanical parabolic dish is severely limited in the number of objects that can be tracked per unit of time. The object has to pass through the narrow beam.

There's a trade-off between sensitivity and number of objects you can track, and mechanical steering is inferior to phased arrays for rapidly changing targets.