Is it better to make astronomical observations from the Moon's surface or from a low earth orbiting observatory?
One of the main reasons why there is a push to construct a base
on the moon is because telescopic observations from the moon would
be clearer due to the fact that there would be no interference from
an atmosphere, as is experienced on the Earth.
The heavy mirror in a large telescope becomes distorted in a
gravitational field when fixed on the earth, which would happen
even on the moon with its reduced gravity. This reduces the quality
of the image. Actuators placed under the mirror are used to
minimise this effect in some large modern telescopes (called active
optics, see reference).
However, orbiting the earth in space the telescope mirror
becomes weightless and these effects can be virtually eliminated.
This simplifies the telescope design and the subsequent image
quality should be improved.
An orbiting telescope would also be cheaper to launch and
service than one located on the Moon.