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Lunar Lens Takes A Step Forward
palewook writes "A recent breakthrough increased NASA's interest in a lunar-based space telescope. Researchers combined an ionic liquid surface and a layer of silver which produced a favorably reflective mirror."
Actually, I took a physics class a few years ago given by the lead researcher (Ermanno Borra) here at Laval U., and I remember him describing that for ionic liquids the damping can be extraordinarily high, so there are almost no image distortions coming from vibrations.
Not that old canard again. Glass is an amorphous solid, it is not a liquid (at ordinary temperatures). (And no, thickness differences in medieval stained glass windows don't prove anything - the pieces were installed thick side down for stability, and they didn't have the technology for uniform-thickness glass).
They're talking about real liquids, spun to form a curved surface. Early liquid mirror experiments involved mercury.
-- Alastair
Hell the placement makes us drool as ANY functioning telescope data from the far side of the moon would probably give us new and tantalizing images.
The telescope works with gravity, there's no gravity in space. More precisely, there is, but you are continuously falling so you don't feel it. However, you could use a telescope that slowly falls towards the sun and use the solar wind to stop it from falling and also create a weak gravity force. Could be enough to build your telescope in space.
Static electricity is one thing that keeps moving dust around on the moon. And then there's ejected material from meteor impacts (with gravity that low, stuff kicked up by meteors can travel quite far)
Visible light interferometry is damned difficult because of the small wavelengths involved. Also, even though and interferometer gives you the same angular resolution as a similar sized single element telescope it doesn't give you the same sensitivity to faint objects because of the smaller overall surface area of the objective. Plus, really big telescopes are inherently cooler.
You are so boring that when I see you my feet go to sleep.
They do have existing spinning liquid mirrors in service, one of which is in Whistler BC. At this time I don't remember the name of the observatory. The article I read outlined the stringent engineering requirements both to prevent vibrations as well as turbulence generated by the motion of the water.
How that would be applied on a lunar observatory is another story.
The moon has tectonic activity.
Also, as others have mentioned, it gets hit with stuff, since, as you mention, there is no atmosphere.
UBC has a telescope whose primary reflector is a spinning liquid mercury mirror http://www.astro.ubc.ca/LMT. It forms a paraboloidal reflective surface, which is one of the optimal reflector shapes, but can only be aimed at the zenith. A larger (6m diameter) version is being constructed for installation at the same facility near Vancouver.
Smaller liquid-mirror telescopes were designed in the late 19th century, and a 51cm diameter example was built in the early 20th century (by Robert Wood) http://en.wikipedia.org/wiki/Robert_W._Wood. Wood's design suffered from intermittent ripples on the surface, but performed well at other times.
At least Canada is closer than the Moon, and easier to get to (not necessarily less inhospitable, of course).
Those who can make you believe absurdities can make you commit atrocities. - Voltaire