The biggest MELFF ever could be right next door. Where is your telescope when you need it?

Even by astronomical standards, Roger Angel thinks big. Angel, a leading astronomer at the University of Arizona, is proposing an enormous liquid-mirror telescope on the moon that could be hundreds of times more sensitive than the Hubble Space Telescope. Using a rotating dish of reflective liquid as its primary mirror, Angel's telescope would the largest ever built, and would permit astronomers to study the oldest and most distant objects in the universe, including the very first stars.

Angel dreams of a 100-meter mirror, which would be larger than two side-by-side football fields and would collect 1,736 times more light than the Hubble. Even a 20-meter instrument, which is more likely in the near term, would be 70 times more sensitive than the Hubble and could detect objects 100 times fainter than those that will be seen with the James Webb Space Telescope, a next-generation orbiting observatory scheduled for launch in 2013.

There are many advantages to building a deep-space telescope on the moon. A lunar LMT would be free from the atmospheric distortion that afflicts terrestrial telescopes of all kinds, and from the self-generated winds that produce troublesome waves in the largest earth-based LMTs. The light from the universe's most distant stars is intensely red-shifted, and the airless lunar deep-freeze would be ideal for infrared observation – as would a liquid mirror: While they perform as well as conventional mirrors at visible wavelengths, liquid mirrors do even better in the infrared.

Alas, the same low temperatures that would facilitate infrared observation would also turn mercury, the liquid used in terrestrial LMTs, into a solid. So the greatest technical challenge for Angel's team lies in finding reflective liquids with low freezing points and vapor pressures – liquids that would neither freeze nor evaporate into space. That task fell to Ermanno Borra, a physicist and liquid-mirror pioneer at Laval University in Quebec who first made the case for a lunar LMT in 1991. Recently, Borra has been experimenting with metal liquid-like films, or MELFFs, that reflect light as effectively as aluminum.

A plan to build a giant liquid telescope on the moon. (Wired)