An international team including researcher Ermanno Borra, from Université Laval’s Center for Optics, Photonics, and Laser, have found a combination of materials that allows the creation of a highly reflective liquid mirror capable of functioning even on the moon's harsh landscape.
Science fiction? Not at all.
Liquid mirror telescopes differ from conventional telescopes by their primary mirrors—the ones that gather and focus light—which are made from a reflective liquid instead of polished glass. Poured into a spinning container, the liquid spreads out and forms a thin, perfectly smooth, and parabolic shape that can be used as a telescope mirror.
3.7-m diameter liquid mirror at Laval University. The liquid is mercury. There are no detectable mercury vapors in the air because a thin transparent layer of oxide covers the surface. Photo taken by Guy Plante (Laval)
In a 1991 paper Borra explained how an observatory free from the Earth’s atmospheric disturbance could further our understanding of the early universe.
The project gained interest in 2004 when it received financial support from the NASA Institute for Advanced Concepts, an organization which funds projects that can potentially push back the limits of science and space technology.
The project’s main challenge consisted in finding a liquid capable of resisting the conditions on the moon’s surface and functioning in temperatures required for infrared observations, i.e. below -143 degrees Celsius.
To do this, they coated an ionic liquid with silver by vaporizing it in a vacuum, something never achieved before in the field of optics. The resulting silver layer is perfectly smooth, highly reflective, remains stable for months, and the ionic liquid on which it lies does not evaporate.
The liquid mirror envisioned for the lunar telescope would be 20 to 100 meters in diameter, making it up to 1,000 times more sensitive than the proposed next generation of space telescopes.
Such a lunar telescope will not be available to researchers in the near future, admits Borra. “However, if we hadn’t found the solution described in our article in Nature, it would have meant the end of the whole project.”
Source: Université Laval