The idea of building a liquid mirror telescope to view stars from 13 billion years ago on the surface of the Moon has been gathering dust on NASA’s “shelves” for a few years. Now, a group of astronomers from the University of Texas in Austin (USA) wants to bring back this project that apparently was somewhat unusual: a liquid mirror telescope of no less than 100 meters in diameter and built on the surface of the moon. Viable?
This telescope could study Population III stars
More than a decade ago (in a 2007 article published in the journal Nature ) of this idea that is based on the fact that, instead of placing a solid mirror, which would be a heavy, expensive and fragile material, a metallic liquid layer would be used. and reflective (like mercury) that would float over a massive tank of another liquid, making it lighter and more transportable. To achieve this size of 100 meters as a primary mirror, it would constantly rotate over another layer of reflective liquid to achieve the correct parabolic shape. Its objective? Looking back in the first moments after the creation of the observable universe, away from the hustle and bustle of the Earth, towards the elusive Population III of stars (which would have been several hundred or even a thousand times more massive than the Sun, giant stars , hot and bright that we have never seen).
“The theory predicts that there was an earlier time, when galaxies did not yet exist, where individual stars first formed: the elusive Population III stars. This moment of ‘first light’ is beyond the capabilities of even the powerful JWST, and instead you need a ‘definitive’ telescope ”, explains Volker Bromm, theoretical physicist and co-author of the work.
It is true that as we develop more innovative instruments, our astronomical knowledge is improving and becoming more and more accurate, which is why there are more and more telescopes looking towards the limits of the universe, during their first days of life. However , surpassing these limits requires revolutionary approaches, such as this idea of the lunar liquid mirror telescope, which, in addition, would be significantly cheaper than building a regular one.
Why on the Moon?
Without all these effects of the Earth’s atmosphere, the telescope, initially baptized as the Lunar Liquid Mirror Telescope (LLMT), would reach a clarity never seen before, far from terrestrial contamination and any glimmer of light. (Now it has earned the nickname “incredibly large telescope”).
“Such telescopes, perhaps 100 meters in diameter, could see the early phases of the universe after the Big Bang,” the authors commented in their 2007 article.
The telescope would operate autonomously from the lunar surface, probably a crater (from either of the Moon’s poles) receiving power from a solar power collection station on the Moon itself, which would transmit data to a satellite in lunar orbit and, from there, to us: to Earth.
Is it as strange as it seems?
Not really. There are telescopes like the Large Zenith Telescope in British Columbia, Canada, one of the largest telescopes in the world, which is precisely a liquid mirror telescope; although its diameter is only 6 meters, of course.
The telescope would be stationary and would be continuously studying the same patch of sky, collecting enough light to pierce the darkness of the Cosmic Dark Ages and catch the faint light from these distant stars of more than 13 billion years ago.
Referencia: Anna T. P. Schauer et al, The Ultimately Large Telescope—what kind of facility do we need to detect Population III stars? Astrophysics of Galaxies arXiv:2007.02946v2 , arxiv.org/abs/2007.02946
