NASA Liquid-Mirror
Telescope On Moon Might See Deeper Back In Time
(21 June 2007) Someday, astronauts on
the moon may pour liquid onto a disc-shaped mesh to make a huge mirror for a
powerful telescope, according to a technical article just made
public.
The liquid would include a silver-coated surface, and
would be part of an optical-infrared telescope with a 66-foot (20-meter) to
328-foot (100 meter) aperture capable of observing objects 100 to 1,000 times
fainter than the James Webb Space Telescope, the authors say. The technical
paper will appear in the June 21, 2007, issue of the journal,
Nature.
"In this case we have shown how the moon is ideal (for) using
liquid mirror technology to build a telescope much larger than we can
affordably build in space," said S. Pete Worden, director of NASA Ames Research
Center in California's Silicon Valley, and a co-author of the technical paper.
The lead author is Ermanno Borra, Laval University, Quebec, Canada. "Such
telescopes, perhaps 100 meters in diameter can see back to the early phases of
the universe after the Big Bang," Worden added.
The authors envision
making lunar, infrared telescopes to study normal and dwarf
galaxies.
"The lunar, liquid-mirror project was supported by the NASA
Institute for Advanced Concepts. It enabled a team of scientists including
myself to show how the moon - our first target in the Vision for Space
Exploration (VSE) - might support astronomy," Worden explained. " We hope that
this or similar possibilities will excite the scientific community about the
opportunities contained within the VSE," Worden observed.
According to
the article, an uncoated mirror would be carried to the moon in a drum that
astronauts would empty into a rotating mesh, robotically unfolded like an
umbrella.
"Surface tension would prevent the liquid from falling through
the small holes of the mesh," the authors said.
The major advantages of
liquid telescope mirrors include ease of shipping, assembling and maintenance,
"which are far easier than for a solid mirror," the authors note.
In
laboratory experiments, the researchers used a liquid made of 'ionic salts'
that remains fluid at very low temperatures. The scientists deposited a fine
layer of chromium particles on the liquid and then added a layer of silver
particles. The researchers say that the reflectiveness of the liquid mirror is
not yet adequate, but "it is now only a matter of technological
improvement."
The authors say they will continue to experiment to
develop more ways to make liquid mirrors. The researchers predict that the
first lunar, liquid-mirror telescope will be built no earlier than
2020.
Borra received a grant from the Canadian Space Agency to conduct
his studies. The other authors include: Omar Seddiki of Laval University,
Quebec, Canada; Roger Angel and Daniel Eisenstein, both from the University of
Arizona, Tucson; Paul Hickson, University of British Columbia, Vancouver,
Canada; and Kenneth Seddon, The Queen's University of Belfast,
U.K.
(source: NASA Ames Research Center)