Modern astronomy started with telescope lenses made of glass.
The lenses got bigger and bigger until limits of the tech was reached.
Later mirrors took over and today their technological limits approaching.
That means building new astronomical observatories with bigger mirrors becoming too expensive/hard.
But what if lenses have more to give to astronomy?
What if there was a way to combine the powers of biggest mirrors with biggest lenses?
I think it is possible to change the refraction index of air with (infrared?) lasers and/or ultrasound.
Imagine a laser scanner that scans the air in front of an astronomical telescope
or a big (phased) array of ultrasound emitters
and both/either of which creates a giant virtual lens in the air in front of the telescope.
(Imagine, by doing adjustments, the focal length/point of the virtual lens can be adjusted as needed.)