[mturmon]

Yes, the spy satellites were first by a long shot. The KH-11 (2.4m mirror, CCD focal plane) was first launched in 1976. Hubble (2.4m mirror, CCD focal plane) was launched in 1990.

The shared mirror size is not a coincidence: https://en.wikipedia.org/wiki/KH-11_KENNEN#Size_and_mass

The two also share a multi-billion dollar budget.

[6nf]

The mirror size is largely limited by the size of the vehicle launching the satellite into space, if I recall correctly.

[ArnoVW]

Which in turn is based on the size of a equine derriere, as the story goes.

https://www.precisioncontent.com/blog/on-rocket-ships-and-ho...