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Putting An Observatory On The Moon's 'Dark' Side
wytcld writes: "CNN reports astronomers are pushing for a radio telescope on the 'dark side of the moon' (do real astronomers call it the 'dark side,' when it gets plenty of light?). The proposal by Yuki David Takahashi is amazing mostly because a guy just starting work on his Master's is managing major press for it. Still, a nice dream."
The Earth and moon are 384,000 km apart. Given the masses of each, the gravitational balance point is at 346,000 km from the center of the Earth. The moon has a radius of 1,700 km. Consequently there is a region from about 100-9,000 km above the surface of the moon that would give reasonably stable circular orbits (at least with respect to a satellite lifetime of say 20 years). It does however rule out any lunar-synchronous satellites since they would be well outside the quasi-stable region.
Since we want the base on the dark side of the moon, we do in fact need some way to talk to it. One possibility is of course putting up a satellite around the moon, and whenever it flys over the telescope picking up the data and sending it back during it's next pass near the earth. Or a series of lunar satellites could relay continual contact. Alternatively you could build relay station on the Earth facing side and establish some kind of connection to the other side (lots of fiber optic cable, laser relay towers, etc.)