Liquid telescope to be put on the moon

Scientists are hoping to get near perfect views of stars and distant galaxies by putting a telescope on the moon.

The lack of atmosphere on the moon offers the potential of improved stellar images

The instrument will have a mirror consisting of a liquid with a thin metal film on its surface that rotates to form a bowl shape, known as a parabola. When the liquid spins in a perfect parabola, it will be able to reflect infrared light from distant stars and galaxies that cannot be picked up by telescopes on Earth because of atmospheric interference and light pollution.

A team from Queen’s University in Belfast has been investigating the possibility of preparing a reflective liquid for the telescope. It will consist of an ionic liquid that can be coated on its surface with a thin layer of a reflective metal.

“The discovery that an ionic liquid can be coated with a very thin metal layer is a major breakthrough,” said chemistry professor, Ken Seddon, director of Queen's University Ionic Liquids Laboratories (QUILL).

Telescopes with parabolic liquid mirrors are much cheaper and easier to make and maintain than conventional telescopes with glass mirrors. Liquid mirror telescopes employed in observatories on Earth traditionally use mercury as the reflective liquid. However, mercury cannot be used for a lunar liquid mirror telescope as the high-vacuum conditions on the Moon would cause the mercury to boil.

Ionic liquids generally have negligible vapour pressures - meaning that they do not boil, even under vacuum. Many ionic liquids do not freeze at the sub-zero temperatures found on the Moon, they also have the added advantage that they are much lighter than mercury - a key consideration for transporting a telescope to the Moon.

In a report in the journal Nature, the Belfast, Canadian, and U.S. scientists showed that a commercially-available ionic liquid can be coated with silver and that the coated fluid is stable over several months.

According to Seddon, around one million simple ionic liquids are theoretically possible and they can be designed for a wide variety of applications.