Scientists working at
NASA's Goddard Space Flight Center in Greenbelt, Md., have concocted an
innovative recipe for giant telescope mirrors on the Moon. To make a mirror
that dwarfs anything on Earth, just take a little bit of carbon, throw in
some epoxy, and add lots of lunar dust.
"We could make huge telescopes on the moon relatively easily, and avoid
the large expense of transporting a large mirror from Earth," says Peter
Chen of NASA Goddard and the Catholic University of America, which is
located in Washington, D.C. "Since most of the materials are already there
in the form of dust, you don't have to bring very much stuff with you, and
that saves a ton of money."
Chen and his Goddard colleagues Douglas Rabin, Michael Van Steenberg,
and Ron Oliversen are presenting their mirror-making technique in a poster
at the 212th meeting of the American Astronomical Society in St. Louis, Mo.
They will also describe their results in a press conference on Wednesday,
June 4 at 9:30 a.m. CDT.
For years, Chen had been working with carbon-fiber composite materials
to produce high-quality telescope mirrors. But Chen and his colleagues
decided to try an experiment. They substituted carbon nanotubes (tiny
tubular structures made of pure carbon) for the carbon-fiber composites.
When they mixed small amounts of carbon nanotubes and epoxies (glue-like
materials) with crushed rock that has the same composition and grain size
as lunar dust, they discovered to their surprise that they had created a
very strong material with the consistency of concrete. This material can be
used instead of glass to make mirrors.
They next applied additional layers of epoxy and spun the material at
room temperature. The result was a 12-inch-wide mirror blank with the
parabolic shape of a telescope mirror. All of this was achieved with
minimal effort and cost.
"After that, all we needed to do was coat the mirror blank with a small
amount of aluminum, and voila, we had a highly reflective telescope
mirror," says Rabin. "Our method could be scaled-up on the moon, using the
ubiquitous lunar dust, to create giant telescope mirrors up to 50 meters in
diameter." Such an observatory would dwarf the largest optical telescope in
the world right now: the 10.4-meter Gran Telescopio Canarias in the Canary
Islands.
The capabilities of a 50-meter telescope on the Moon boggle the
imagination, according to NASA. With a stable platform, and no atmosphere
to absorb or blur starlight, the monster scope could record the spectra of
extra solar terrestrial planets and detect atmospheric biomarkers such as
ozone and methane. Two or more such telescopes spanning the surface of the
Moon can work together to take direct images of Earth-like planets around
nearby stars and look for brightness variations that come from oceans and
continents. Among many other projects, it could make detailed observations
of galaxies at various distances, to see how the universe evolved.
"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 notes that his group achieved this breakthrough with only the
support of small NASA internal seed funds. The carbon nanotubes were
contributed by Dan Powell, Lead Nanotechnologist for NASA Goddard. Several
amateur astronomers made key contributions by advising and making special
epoxy formulations, helping with polishing experiments, and vacuum coating
the 12-inch mirror.
Source: NASA
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