I wonder what is the approach to replace let's say: 5 defective Starlink satellites, each one in a different orbit? I guess that it can't be done with just one launch as the krypton ion thrusters delta-v is low and should be used to avoid collision, orbit raising and re-entering.
There are a lot of possibilities. A few things to keep in mind.
- The early days of Starlink will not have guaranteed 100% uptime.
- Starlink requires a 40 degree above the horizon line of sight. This is actually very large, many satellites only require 10 or even 5 degrees. This means that there has to be a lot more Starlink satellites, but there might be a bit of spare capacity if you spread them out.
- Eventually the increase in satellite count will be more dictated on increased capacity, and not on redundancy. A few single missing satellites won't make a huge difference.
For the early days, I predict they will space out the satellites in the same plane a bit more for the short term. For the long term, they will have a few on-orbit spares, or new launches, where one of the satellites will be put in an orbit to gradually move it to the correct plane.
For later days, there will probably be some spares in the plane, so simply moving one of those around can be done, and will only take a few days. That will leave a "hole" where periodically the capacity will drop slightly, but that probably isn't a huge issue in the grand scheme of things.