Rotating Mercury Lunar Observatory

Fraser Cain writes "Universe Today is reporting on a proposal under consideration by NASA from Dr. Robert Angel at the University of Arizona. He wants to build a 100-meter liquid mirror telescope into a crater on the Moon. It would only be able to look at a specific spot in the sky, but the view would bury Hubble's Deep Field Survey." The challenges of off-Earth construction are left as an exercise for the reader.

Comments

Difficult to send to space

[reverseengineer]

This is a neat idea, but liquid mercury has a density of 13593 kilograms/cubic meter. The article does not mention how deep the pool of mercury would be, but even if the mercury is only 1 cm deep, my back of the envelope calculations for a 100m mirror (which treat the mirror as a cylinder with radius 50m and height 1cm) would require 1068 metric tons of mercury.

First off, this far outstrips our present launch capability. Second, we would require a much more reliable method of sending things into space before we decided to send up a significant amount of liquid mercury, given that a failed launch of a rocket carrying a large tank of mercury would be a major ecological disaster. It's a great idea in theory- pouring a bunch of liquid into a bowl would be certainly preferable to the tremendous amount of skill and effort required to properly build and polish large telescope mirrors- but I'm not sure how long it would be before this idea becomes even remotely practical.