ABSTRACT.

A large, liquid mirror telescope on the moon could provide invaluable observations of the early universe. However, current liquid telescopes are unsuitable for observations in the infrared (IR), where much interesting science is expected. While there are many significant engineering challenges for such a telescope, the lack of a suitable liquid has been a major factor limiting discussion. Here we argue that liquid lithium ammonia should be a suitable operating liquid. It has a high reflectivity in the IR, a low melting point (89 K), a low density (0.5 g cc^-1), and extrapolation of its measured vapor pressure indicates that it is suitable for lunar vacuum.