A DEEP-FIELD INFRARED OBSERVATORY NEAR THE LUNAR POLE

We have studied the feasibility and scientific potential of a 20 100 m aperture astronomical telescope at the lunar pole, with its primary mirror made of spinning liquid at less than 100K. Such a telescope, equipped with imaging and multiplexed spectroscopic instruments for a deep infrared survey, would be revolutionary in its power to study the distant universe, including the formation of the first stars and their assembly into galaxies. Our study explored the scientific opportunities, key technologies and optimum location of such a Lunar Liquid Mirror Telescope (LLMT). An optical design for a 20 m telescope with diffraction limited imaging over a 15-arcminute field has been developed. The LLMT could be used to follow up discoveries made with the 6 m James Webb Space Telescope, with more detailed images and spectroscopic studies, as well as to detect objects 100 times fainter, such as the first, high-red shift stars in the early universe. A model was made of a liquid mirror spinning on a superconducting bearing, as will be needed for the cryogenic, vacuum environment of the LLMT. Reflective silver coatings have been deposited for the first time on a liquid surface, needed to make infrared mirrors at ~ 80K. Issues relating to polar locations have been explored. Locations at or within a few km of a pole are preferred for deep sky cover, and allow for long integration times, by simple instrument rotation. In a collaborative effort with the European Space Agency’s SMART-1 lunar orbiter team, we obtained the first images of the North Pole in lunar winter. SMART-1 arrived at the Moon in November 2004 and has since spiraled down to a polar orbit. During the commissioning period and between orbit modifications, the orbiter imaged strips of Moon with its 5°× 5° AMIE camera. We analyzed available images of the North Pole region acquired during that period, which was close to the January 25th 2005 winter solstice. Our preliminary analysis shows ridges and crater rims within 0.5° of the North Pole are illuminated for at least some sun angles during lunar winter. Locations near these points may prove to be ideal for the LLMT. Lunar dust deposited on the optics or in a thin atmosphere, though unlikely, could be problematic. These issues should be further investigated in-situ and we propose a modest precursor site survey mission. RATIONALE FOR A LUNAR LIQUID MIRROR TELESCOPE (LLMT) Our lunar liquid mirror telescope concept is aimed at furthering our understanding of the early universe. This has recently been revolutionized by deep optical fields imaged first with the Hubble Space Telescope (HST), and followed up by observations by other telescopes across the electromagnetic spectrum, including