[aphextron]

>By the time this thing launches we might see trials of both, but certainly there won't be something readily available for service operations on the JWT at the time it launches.

Servicing the JWST with astronauts like we did with Hubble will be impossible, as it will be parked in one of earth's L2 points, not in LEO. Basically, everything has to work absolutely flawlessly on the first try, or that's it. Billions of dollars and decades of work gone.