The Devasthal Observatory is located in the Indian Himalayas at an altitude of 2450 m. It is both too high and too far, because astronomers have to endure a 10-hour trip to the Himalayas to get there. But this is the way, because there they can look into space through a liquid mirror telescope (ILMT).
The International Liquid Mirror Telescope (ILMT) is 4 meters in diameter and is the first liquid telescope built specifically for astronomy. Most telescopes use glass mirrors, but as the ILMT suggests, its mirror is made of a 10 microns thick layer of mercury that floats in compressed air and rotates every 8 seconds.
“By way of comparison, a human hair is approximately 70 microns thick. The air bearings are so sensitive that even smoke particles can damage them.” – said Dr. Paul Hickson, a UBC Physics and Astronomy Professor and a liquid mirror technology pioneer.
The rotation causes the liquid mercury to take on a parabolic shape, similar to a contact lens, which allows the telescope to focus light from deep space. In fact, the mirrors of glass telescopes are also parabolic, but it takes much more effort to shape a solid material, so telescopes with liquid mirrors are much more cost-effective than conventional ones.
The trade-off is that the ILMT is fixed in one position, so it observes only one strip of the night sky as the Earth rotates beneath it. But because the telescope will focus on only one area, it is well suited for observing moving objects such as supernovae and asteroids.
Scientific observations are expected to begin later this year, with ILMT operating from October to June every year, closing operation in the rainy season. The project is an international collaboration between institutions in India, Belgium, Poland, Uzbekistan and Canada.