Can 85 ILMT be built in a sky eye?Scientists say liquid telescope can be built on the moon

This is the world's first liquid telescope for astronomy.

It can be seen from this over -view view that the international liquid mirror telescope (ILMT) is not the same as the traditional telescope. This telescope uses a rotating disc with 50 liters of silver. And this picture is presented by a layer of polyclic film attached to the mercury mirror.

Why do you make a liquid telescope? Why is mercury? ... When ILMT began to receive the early light at the Devasthal Observatory at the Himalayas' 2450 meters high, some questions began.

How does mercury "look far away"?

It must be emphasized that it is not the earliest mercury telescope.

Prior to it, the world's largest liquid metal telescope was LZT, a large -scale sky telescope located in Canada. It was built in 2003, with a caliber of 6 meters and a spatial resolution of 1.4 cents. However, the scientific goal of LZT is a long -term high -resolution observation of the dynamic characteristics of the sodium sodium layer. The observation results are extremely influential in the international self -adaptive optical field.

As for why you choose mercury?

The idea of ​​ILMT appeared in the 1990s. But in fact, as early as 1850, the Italian astronomer Onest Capos suggested that the rotating discs with mercury are the main mirror of the telescope. Unfortunately, under the technical conditions at that time, it was not easy to make the liquid mirror smooth rotation, which directly delayed the time when the "finished product" appeared for more than a century. However, its basic concepts have not changed, and it is still based on the "water and silver rotation disc" as the main mirror.

ILMT relies on a rapidly rotating 4 -meter (13 -foot) reflector, and the reflector is covered with a layer of mercury to capture cosmic light. In theory, as long as we can create a large parabolic surface, we can make the telescope have a corresponding lighting ability.

Under normal circumstances, such a parabolic surface is made of huge mirror blank, such as 500m aperture ball surface radio telescope -FAST. However, a series of technologies such as mirror blank manufacturing, mirror polishing, and reflective surface coating, both in terms of complexity and cost, mean huge consumption.

The liquid mirror is different.

Scientists believe that after a plate is installed with reflective mercury, when the plate is rotated, due to the impact of gravity and centrifugal force, the mercury inside will gradually form a stable parabolic surface. At this time, there is no need to go through the process of mirror casting like a traditional telescope at all.

It is reported that ILMT is worth $ 2 million (about 13.39 million RMB). Just in the same Observatory, another optical telescope (DOT) not far from it, the cost is $ 18 million.

If you find some more familiar cases, the cost of China Eye Fast costs 1.15 billion yuan, which can create almost 85 ILMT; and NASA's space telescope "Weber" costs up to $ 9 billion, equivalent to 4,500 ILMT.

Advance into the moon

Compared with the celestial telescope, the advantage of ILMT is that it can observe the fleeting change in the same sky because it is extremely sensitive to the brightness of the celestial body.

To put it simply, under this advantage, ILMT can obtain extremely finely delicate and weak celestial images by superimposing multiple night exposure images; the second is to reveal the short -lived celestial and distant galaxies by comparing the image of different nights before and after different nights. The light and dark changes affected by the black hole.

In a sense, this is a powerful supplement to the sky -to -end telescope, and there is no "replacement" problem. The most obvious point is that the traditional telescope constructed can be adjusted to observe. However, ILMT must ensure that the mirror surface is stable, and it can only be observed in the direction above the head. This is why LZT was called "Sky Telescope".

But the emergence of ILMT also means another high hope for humans: building a larger liquid telescope on the moon.

As early as 1991, Canadian scholar Elmanno Bora published an article in "Grand Physics Magazine" and suggested building a liquid telescope on the moon. He believes that "telescopes that are not disturbed by the earth's atmosphere can enable people to study early in the universe."

By 2020, scientists at the University of Texas University in the United States proposed the concept of "ultimate telescope". They said that this will be a "cannonable telescope that can directly observe those elusive first stars at the edge of the time." The main mirror is composed of rotating liquid with silver plated on the surface.

For scientists, the biggest problem of liquid telescope landing is to find a liquid that can withstand the harsh conditions of the moon and work effectively.

The reason why mercury is optimistic is that on the earth, the Corioli effect caused by rotation will distort the mercury movement in a mirror greater than 8 meters. But the moon rotates slowly and can form a larger liquid lens.

However, the problem of mercury is not small. For example, how to transport mercury to the moon? The temperature difference between the moon is huge. What should I do if the mercury evaporates during the day and the custody at night?

Ten years ago, Elmanno Bora introduced the method of "evaporating silver in the vacuum and applying to ionic liquid" in the "Nature" magazine, saying that the silver slices prepared by this are very smooth. The reflection performance is excellent, "and" can remain stable within a few months, and the ionic liquid relied on silver tablets has not evaporated. "

"There is still a long way to go". When talking about the "moon landing" dream, different scientists have mentioned this sentence.Today, ILMT has been completed, it is reported that it will run from October to June each year, and the Indian rainy season is closed.With its operation, the road of "liquid telescope" can be further ushered in a new variable.

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