Recipe for giant lunar telescopes
BY DR EMILY BALDWIN
ASTRONOMY NOW
Posted: June 5 2008

Scientists working at NASA's Goddard Space Flight Centre have concocted an innovative recipe for making giant telescope mirrors on the Moon: simply take a pinch of carbon, a handful of epoxy, and a generous helping of lunar dust.

The Moon, as captured by Apollo 12 astronauts as they left the surface of our scarred satellite. Scientists hope to build telescopes on the Moon using lunar dust, and even suggest lining the ready-made parabolic depressions known as impact craters with large mirrors. Image: NASA.

"We could make huge telescopes on the Moon relatively easily, and avoid the huge expense of transporting a large mirror from Earth," says Peter Chen. "Since most of the materials are already there in the form of dust, you are no longer restricted by the size and weight that a rocket can carry, and that saves a ton of money."

Chen and his team had been working on carbon-fibre composite materials to produce high quality telescope mirrors when they decided to spice things up a bit. They substituted pure carbon for carbon-fibre composites and mixed in small amounts of epoxies (glue-like materials) with crushed rock that has the same composition and grain size as lunar dust. To their surprise, they discovered that they had created a very strong material with the consistency of concrete. They spun their concoction at room temperature, adding additional layers of epoxy, and created a 12-inch-wide parabolic mirror form, which could be coated with aluminium to create a highly reflective surface.

"Our method could be scaled-up on the Moon, using the ubiquitous lunar dust, to create giant telescope mirrors up to 50 metres in diameter," says Chen. Such an observatory would dwarf the largest optical telescope in the world right now: the 10.4-metre Gran Telescopio Canarias in the Canary Islands.

The Gran Telescopio Canaria (GTC), shown here during construction and after completion, is currently the world's largest telescope. Telescopes on the Moon could be  over five times the size of the GTC. Images: GTC.

The capabilities of a 50-metre telescope with a stable platform and no atmosphere to absorb or blur starlight, would be unrivaled. The titanic telescope would be capable of recording the spectra of extrasolar Earthlike planets and detecting atmospheric biomarkers such as ozone and methane. Two or more such telescopes spanning the surface of the Moon could work in parallel to provide an even more powerful telescope array. Among many projects, it could make detailed observations of galaxies at various distances to see how the Universe evolved. Chen also fantasizes that mirrors could line the ready-made bowl-shaped morphologies of lunar craters that were carved out by the impact of asteroids or comets millions and billions of years ago.

"Constructing giant telescopes provides a strong rationale for doing astronomy from the Moon," says Chen. "We could also use this on-site composite material to build habitats for the astronauts, and mirrors to collect sunlight for solar-power farms."

Chen is keen to point out that his project was only made possible by a small NASA fund, donations of equipment from interested parties, and advice and help from amateur astronomers.