India installs world's first liquid mirror telescope

India installed the world's first liquid mirror telescope dedicated to astronomy at Devasthal Observatory, Uttarakhand state, India Times reported on June 9. The instrument, called the International Liquid Mirror Telescope (ILMT), is expected to observe asteroids, galaxies, supernova explosions, space junk and many other objects.

An aerial view of the ILMT at ARIES' Devasthal Observatory showing a liquid mercury mirror coated with a thin mylar film. (Photo: ARIES)

Located at an altitude of 2,450m, ILMT was installed in cooperation with Belgium, Canada, Poland, Uzbekistan. The glasses were designed and manufactured by the Advanced Mechanical and Optical Systems Joint Stock Company in collaboration with the Liège Space Center in Belgium. The Aryabhatta Research Institute of Observational Sciences (ARIES) in India will own and operate the device.

It is the first liquid mirror telescope built specifically for astronomy and also the only one of its kind in operation in the world. "Only a handful of liquid mirror telescopes have ever been built, but mainly for satellite tracking or military purposes," said Dr. Kuntal Misra, an expert at ARIES.

"Different from conventional telescopes that can be adjusted to track certain objects, the ILMT will be stationary. It will make observations and take pictures of the zenith region, that is, the sky directly above. is a survey telescope with high potential to detect new objects," Misra said.

Liquid mirror telescopes are made up of mirrors with a reflective liquid, in this case mercury, which has a high ability to reflect light. About 50 liters of mercury, or nearly 700 kilograms, were poured into the reservoir. The chamber rotates at a fixed speed along the longitudinal axis of the ILMT. This process causes the mercury to spread like a thin layer in the cavity, forming a parabolic pan-shaped reflective surface that acts like a mirror. This surface is ideal for gathering and focusing light.

The ILMT mercury mirror is 4 m in diameter with an aperture of f/2 as determined by the rotational speed. ILMT is capable of generating huge amounts of data, around 10-15 GB per night. The telescope is expected to operate for the next five years, starting in October 2022.