This question came to mind after hearing about Starshot: Basically you take small spacecraft and accelerate them to 0.2c and make them fly for a few years to Alpha-Centauri at which point it then shoots some pictures back.
They have a lot of things they need to improve to even come remotely close to their goal, but there is one thing that struck me as being potentially unfeasible (there might be others), and that is actually aiming towards Alpha-Centauri or even worse, back to Earth.
There main thing I am unsure about (and which is ultimately the question here) is it possible (in human feasible terms) to actually aim from earth for something like Alpha Centauri? And can something that small (less than a cm) actually aim to earth from 5ly?
The reason why I don't think so is because:
- Precisely Pinpointing Alpha Centauri is difficult (This gets worse when wanting to point back to Earth)
- It is really far away
The angular resolution of Alpha Centauri is just 0.007" which is pretty small. I am unable to think of a system where if you aim from earth you could actually get a precision of 1AU at 5ly.