Ferrofluid mirror

Water-based ferrofluids hold the reflective layer effectively, but water evaporates so quickly that the mirror could disappear within hours.

[5] The combination of fluid and metal results in a liquid optical surface that can be precisely shaped in a magnetic field.

Ferrofluid mirror telescopes have been built to obtain astronomical data and used to take images of deep space; subjects for research include exoplanets.

The main challenge astronomers and scientists face is image distortions due to wavefront errors caused by the atmosphere.

[6] Mercury was used as the main material of early deformable liquid-mirror telescopes because of its high reflectivity and low melting temperature.

Ferrofluid mirrors use cheaper materials, and are able to make more corrections due to its larger range of motion.