Liquid Mirror Telescope For Moon Studied By NASA
A Lunar Liquid Mirror Telescope (LLMT) is under study thanks to a grant from NASA. J. Roger Angel, a regents professor at the University of Arizona, is leading a project to study the feasibility of a 100 meter LLMT at the moon's south pole.
Why liquid mirrors? Ever since 1668, when Isaac Newton built the first reflector telescope with a one-inch diameter mirror made of metal, astronomers have longed for bigger parabolic mirrors. Opticians expend a great deal of effort to grind larger and larger pieces of glass to just this shape.
Liquid Mirror Telescopes were first talked about several hundred years ago. Imagine a bowl of mercury at the center of a lazy susan. When you give it a spin, the surface of the liquid forms that highly prized shape - a parabola. The bigger the bowl, the bigger the resulting mirror.
The first serious attempts to actually build a LMT took place in the early twentieth century. Robert W. Wood, a physicist at Johns Hopkins University, built a working telescope, but could not accurately control the speed of the turntable, resulting in a mirror with a variable focal length. (The rotation must be controlled to less than one part in 100,000 during exposure.) Pictures of star trails were focused in some places, but blurry in others.
(The Large Zenith Telescope mirror)
The LMT concept has been made to work. The Large Zenith Telescope at the University of British Columbia uses a 6-meter mirror, making it the third largest optical telescope in North America. It was built at a cost of approximately $1 million. A telescope with a conventional glass mirror of the same size would cost $100 million.
It is hoped that similar savings might apply when constructing telescopes on the moon. In addition, the moon is completely free from atmospheric absorptions and distortion.
The only disadvantage of the LMT is that you cannot tilt it; it must remain perpendicular to the local gravitational field. You can only use it to look at what is directly above the telescope; however, a mirror of this size could take a very penetrating look at its patch of sky.
"You would be seeing things farther back in time than anyone has ever seen any galaxy or star or quasar," [Angel] explained. "It could give you a chance to see what was happening at a very early time."
(From J. Roger Angel and the LLMT)
Obviously, for such a project to be attempted, there would need to be substantial infrastructure already im place on the moon. As Dr. Angel remarked, "You could not justify that kind of infrastructure (just) to build this kind of telescope, but if the infrastructure already were there, this is something that looks feasible to do."
There is a very early reference to a large liquid mirror telescope in science fiction; but this LMT is on Mars, not the moon. In his excellent 1934 novella Old Faithful, author Raymond Z. Gallun writes about a Martian named 774, who has a desperate need to contact Earth:
Piercing the dome, opposite the upper end of the cylinder, was a circular opening through which a portion of the starlit sky was visible; and at the base of the cylinder a great bowl rotated rapidly, like a huge wheel...
The bowl contained mercury. As the container spun on its perfectly balanced axis, centrifugal force caused the mercury to spread in a thin, precisely distributed layer over the inside of the bowl, forming a concave surface that acted admirably as a mirror for Number 774's gigantic reflecting telescope. It's area, and its consequent light-gathering capacity, was many times greater than any rigid mirror that could have been constructed without flaws.
(Gallun appears to err in his use of the LMT; read more about the Martian LMT)
Read more about J. Roger Angel and the LLMT, read more about LMTs at Space.com or take a look at the Large Zenith Telescope. Thanks to Winchell Chung for the tip and the sf for this story.
Scroll down for more stories in the same category. (Story submitted 2/5/2006)
Follow this kind of news @Technovelgy.
| Email | RSS | Blog It | Stumble | del.icio.us | Digg | Reddit |
you like to contribute a story tip?
Get the URL of the story, and the related sf author, and add
Comment/Join discussion ( 23 )
Related News Stories -
Shimuzu Luna Ring Solar Power Project
'This was really free power... Power carried across millions of miles on Addison's tight-beam principle.'- Clifford Simak, 1941.
Robot Kirobo Talks With Astronauts Aboard ISS
Robots now converse in space. With humans.
NASA's LADEE Enters Lunar Orbit
'... dust normally on the surface picks up and keeps a charge.' - Hal Clement, 1956.
Nuclear Interceptors Designed For Planetary Protection
See NASA's concept for a nuclear interceptor.
Technovelgy (that's tech-novel-gee!)
is devoted to the creative science inventions and ideas of sf authors. Look for
the Invention Category that interests
you, the Glossary, the Invention
Timeline, or see what's New.
Can Gut Bacteria Make You Smarter?
'Vergil had trained the lymphocytes in the past six months to interact as much as possible with each other and with their environment...'
Shimuzu Luna Ring Solar Power Project
'This was really free power... Power carried across millions of miles on Addison's tight-beam principle.'
AllSee Low Power Gesture Recognition
'It saved a lot of muscular expenditure, of course...'
Must Breaking Up Be Hard To Do?
'Whoever was placed inside the apparatus instantaneously experienced all the charms, lures, wiles, winks and witchery of all the fairer sex in the Universe at once.'
PillCam Colon Now Approved By FDA
'You're going to take a picture of my insides?'
RYNO To Heinlein - Your Tumblebug Is Ready!
'It is about the size and shape of a kitchen stool, gyro-stabilized on a single wheel...'
3D Printing Your Winter Reality
'It makes drawings in the air following drawings it scans with photo-cells...'
Roboroach Now Shipping!
'A cable, here, from the controller to the interface plug... wires from that to the brain.'
MeCam Selfie Nano Drone Like Karen Traviss' Bee Cam
'He set his camera to follow him, and it hovered behind him like a large tame bee.'
AeroLife Inhalable Food Powder
'Now shall the brutal murdering of fellow animals and brother vegetables forever stop...'
Harvest-Time On The International Space Station
We will come rejoicing.
Pop Secret Pop Dongle Lets You Smell The Corn A Poppin' On Your Smartphone
'The joymaker in his hand hissed and sprayed him with something...'
Brain-Dead Pregnant Woman Taken Off Life Support
As described by Frank Herbert.
'Smart Silk' In Quantity
'Strongest stuff in the world, stronger than the best steel. Synthetic spider silk...'
Motorcycle Racing Suit With Airbags
'She jerks the manual release on her cervical collar and goes into full Michelin Man mode...'
Lapel Cameras For LAPD Officers
'Every move they made, were being transmitted to their home unit...'
More SF in the News Stories
More Beyond Technovelgy science news stories