How about a 100 meter telescope mirror?

[thewayne]

There is a type of telescope called an LMT -- Liquid Mirror Telescope. It has a giant dish with a reflective fluid, mercury has been used in the past, that rotates. The motion causes the liquid to form a parabola, thus you have a telescope mirror. There's all sorts of technical problems regarding smoothness of motion, lack of vibration, etc, but it works. The biggest hitch is that it can pretty much only point in one direction -- straight up.

Well, a scientist at University of Arizona is proposing building a 100 meter LMT on the moon! No atmospheric interference, low gravity simplifies all sorts of things. Of course, your shipping costs are kinda steep. The proposal is to make two prototypes on the moon, scaling up to the 100 meter model.

I think this would be tremendously cool if it ever gets built, but I'm not holding my breath.

I've read about this before as there is/was a LMT installation about three miles from Cloudcroft. It was used by NASA to catalog orbital debris and was de-commissioned and the telescope shipped off to other parts, theoretically the facility has been re-opened and houses a new spiffy one-meter, but I haven't seen it yet.

http://www.wired.com/science/space/news/2007/05/liquid_telescope