Are new precision gyroscopes used in spaceflight pretty much all optical?

Question

Gyroscopes are used in spaceflight as parts of inertial systems to monitor spacecraft attitude. They are not absolute, they will drift slowly over time and so need occasional calibration via other measurements such as those provided by star cameras. During launch or other high-thrust and vibration, daytime, and other short duration maneuvers they are indispensable.

Traditionally gyroscopes were based on physically spinning objects, but MEMS-based gyroscopes are used in some applications (perhaps in gyrocompasses as discussed in What is a gyrocompass and how might one be used by a planetary rover?), and ring laser and optical fiber-based gyroscopes offer extremely high performance, lower weight and no moving parts.

Question: These days are new gyroscopes used in spaceflight for precision applications pretty much all optical, or are mechanical gyroscopes still selected in some cases?

note: I'm only asking about gyroscopes used in attitude determination, and not reaction wheels used for attitude control. The distinction is outlined nicely in @OrganicMarble's answer.

Answer 1

A hemispherical resonator is an example of a mechanical gyroscope that has no bearing parts and for practical purposes no moving parts either. See the Wiki page here.

I actually find the description of the principal of operation there a little hard to follow so I've just taken the black box principle, that the vibration patterns in the surface respond to inertial accelerations.

To get back to your question, I think these are used in modern communications satellites often for attitude tranquilisation during manoeuvres. I'd call this a precision application as the pointing often has to be controlled to 0.05 degrees or less. However I don't know what performance issues might lead a designer to chose one of these over a ring laser gyro.