 |
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 |
Would
you like to contribute a story tip?
It's easy:
Get the URL of the story, and the related sf author, and add
it here.
Comment/Join discussion (Back On) ( 23 )
Related News Stories - (" Space Tech ")
Snowboarding On Mars? Heinlein Was Ready
How long ago did Robert Heinlein write about skiing on dry alien worlds?
Could Ground-Based Lasers De-Orbit Space Junk?
'Then their lasers vaporized the smaller satellites...'- Arthur C. Clarke, 1978.
The Interplanetary Internet, Vint Cerf Speaking
'This was the center of Interplanetary Communications.'- George O. Smith, 1942.
30-Day Trip To Mars?
'The Federation Ship Champion... made the crossing under Lyle Drive in only nineteen days.'- Robert Heinlein, 1961.
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.
Current News
Is Noam Chomsky As Paranoid As Philip K. Dick?
'I'm Bill Behren... Operator of fly 33408...'
Low-Cost, Implantable Electronics Get Closer
Better coatings need to become a reality.
'Marauder's Map' Created By Carnegie Melllon
'Is that Dumbledore in his study?'
Cheetah Cub Robot From PKD's Android Dreams
'What about an exact electric duplicate of your cat?'
Dead Cellphone? Try Solar-Powered Public Charging Stations
'Then he saw the geek ... leaning against one of the slender stalks of a sunshade-photocell collector...'
Hungry? Grow Nutritious Insects At Home
'...I balked when my wife served me termites.'
Snowboarding On Mars? Heinlein Was Ready
How long ago did Robert Heinlein write about skiing on dry alien worlds?
Orwell's '1984' Hits Bestseller Lists Thanks To PRISM
'There was of course no way of knowing whether you were being watched at any given moment.'
Roboroach Control? There's An App For That
'A cable, here, from the controller to the interface plug... wires from that to the brain.'
Court OK's DNA Collection Like 'Gattaca'
DNA sampling is not the same as fingerprinting.
Squid Vs. Whale Diorama Liked By Humans, Aliens
'Everything was ready, awaiting the Overlords' pleasure...'
Iceberg Harvesting Off Newfoundland's Coast
'Five hundred billion gallons worth of Antarctic iceberg had been towed into Santa Monica Bay.'
Sony's A4-Sized Flexible Digital Paper Notepad
'...he would plug his foolscap-sized Newspad into the ship's information circuit and scan the latest reports...'
Contact Lens Video Display Electronics Now Transparent
'He realized that it was not quite a clear lens. Speckles of colored brightness swirled and gathered in it...'
Tesla's Supercharge Station Plan
'To recharge the batteries, which can be done in almost every town and village...'
Millimeter-Scale Computing For 'Internet of Things'
'In their megalomania they thought to make the very sand beneath their feet intelligent...'
