Date Published:June 1, 2007
An optical/infrared telescope of 20-100m aperture located on the Moonwould be able to observe objects 100 to 1,000 times fainter than theproposed next generation of space telescopes. The infrared region of thespectrum is particularly important for observations of objects atredshifts z>7. The apparent simplicity and low mass of a liquidmirror telescope, compared with a traditional pointable glass mirror,suggest that the concept should be considered further. A previouslyproposed liquid mirror telescope, based upon a spinning liquid metallicalloy, is not appropriate for infrared applications, which will requirea liquid below 130K. Here we report the successful coating of an ionicliquid with silver. The surface is smooth and the silver coating isstable on a timescale of months. The underlying ionic liquid does notevaporate in a vacuum and remains liquid down to a temperature of 175K.Given that there are ~106 simple and ~1018 ternaryionic liquids, it should be possible to synthesize liquids with evenlower melting temperatures.