[Red Badger]

It seems to me they could have done a coarse adjustment on Earth.....................

[Hootowl99]

Your correct in that an alignment would have done before launch. However, since that time, the satellite has been jiggled and handled transporting to then installing in a cargo bay. After that, it was shot up on a rocket and exposed to high G-force several times and had lots of vibration. Adjustments get out of whack.

There's an animation in the OP article that describes the mirror tuning strategy. It's similar in concept to the strategy a human operator uses in adjusting the focus on a microscope when you sit down to use it. This telescope though is much more though. Eighteen mirrors to align to a single, sharply defined dot. I operated an extremely high end research grade microscope for about 8 years. The tuning of this system is way more than what my setup required. Retired now.