Home https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Science https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ A 100-meter rotating liquid mirror telescope on the moon? Yes please.

A 100-meter rotating liquid mirror telescope on the moon? Yes please.



In the coming years, some really great next-generation telescopes will gather their first light. Between space telescopes such as James Webb and Nancy Grace Romanand terrestrial telescopes such as the Extremely Large Telescope (ELT) and the Magellanic Giant Telescope (GMT), astronomers will be able to study aspects of the universe that were previously inaccessible.

For example, there are stars in population III, which were the first stars to form in the universe. These stars are not visible in visible light, and even next-generation facilities (such as those mentioned above) will not be able to see them. But according to a team led by NASA’s Hubble staffer Anna Schauer, the solution could be to build what she called the Ultimate Large Telescope (ULT) on the moon.

This idea, which was postponed by NASA a decade ago, was set out by Shauer and her colleagues at the University of Texas at Austin in a recent article to be published in an upcoming issue of The Astrophysical Journal. It requires a telescope with a liquid mirror measuring 100 m (~ 330 ft) in diameter and powered by a solar grid that will operate autonomously on the lunar surface, transmitting data to a satellite in orbit.

Impression of the artists from the lunar liquid mirror telescope LLMT) Credit: Steward Observatory / University of Arizona

Professor Volker Bromm, a theorist at UT Austin and co-author of the article, has been studying the first stars to form in our universe for decades. As he explained in a recent news release from the MacDonald Observatory (monitored by UT Austin):

“Throughout the history of astronomy, telescopes have become more powerful, which allows us to study sources from consistently earlier cosmic times – closer to the Big Bang. The upcoming James Webb Space Telescope [JWST] the time will come when galaxies first formed. “

“But the theory predicts that there was an even earlier time when galaxies did not yet exist, but where individual stars originally formed – the elusive stars of population III. This moment of “very first light” exceeds the capabilities of even the powerful JWST and instead needs a “final” telescope. “

The current scientific consensus is that stars in Population III formed several hundred million years after the Big Bang (more than 13 billion years ago). These stars, unlike those existing today, are composed of hydrogen and helium and are relatively short-lived (several million years). Heavier elements form in the cores of these giant stars and they become part of their outer layers, which then blow out when these stars die.

Depiction of an artist on a starship taking off from a lunar base. Credit: SpaceX

This process allowed the formation of heavy metals and silicates, which would allow the formation of planets. This also means that all subsequent generations of stars have a higher metal content (also known as metallicity), which astronomers use to determine stellar age. By studying stars from population III, astronomers will discover much about the evolution of our universe.

Unfortunately, these stars formed during the so-called cosmic “Dark Ages”, when the universe was filled with gas clouds that obscured visible and infrared light. This makes stars of population III invisible in all parts of the near-infrared and radio spectrum, which are currently inaccessible to even our most modern instruments.

Fortunately, calculations by Schauer and her colleagues show that a liquid mirror telescope operating from the moon’s surface could study these stars. The concept, originally known as the Lunar Telescopic Mirror Telescope (LLMT), was first proposed in 2008 by a team led by Roger Angel, a professor of astronomy and optical sciences at the University of Arizona.

After considering this proposal shortly thereafter, NASA chose not to continue the project. According to Neve Drory, a senior researcher at the MacDonald Observatory and co-author of the article, there was no supporting science for the earliest stars at the time. Subsequent studies of Population III stars and NASA’s plans to return to the moon (Project Artemis) make this proposal feasible again.

https://royalsociety.org/-/media/events/2020/03/astronomy-moon/Observatory_on_the_moon-web.jpg?w=400
The artist’s concept of astronomy conducted on the surface of the moon. Credit: NASA

Like the LLMT, ULT will rely on liquids rather than coated glass (which makes transportation to the moon much cheaper. One type of liquid will be arranged in a rotating vessel and the other a metallic liquid (such as mercury that reflects) will The tub will rotate continuously to keep the surface of the liquid in the correct parabolic shape to act as a mirror.

Similar to what NASA, ESA, China and other space agencies are planning – to build a lunar base in the South Pole-Aitken basin – the telescope will be located in the polar regions of the moon (north or south). Within one of the many permanently shaded craters in these ULT regions, there will be no radio or atmospheric interference.

On top of that, he could stare at the same part of the sky all the time and collect as much light as possible in the near-infrared spectrum. As Brom summed up:

“We live in a universe of stars. This is a key question about how star formation began in early cosmic history. The appearance of the first stars marked a decisive transition in the history of the universe, when the primitive conditions set by the Big Bang gave way to ever-increasing cosmic complexity, eventually bringing life to planets, life, and intelligent beings like us.

“This moment in the first light exceeds the capabilities of current or near future telescopes. That’s why it’s important to think about the “supreme” telescope, which can directly observe these elusive first stars at the end of time.

In this illustration, an astronaut carefully descends the ladder and carefully places his foot on the moon. Image credit: NASA

The ultimate light telescope is one of many proposals for a lunar observatory. For example, many recommendations have been made for radio observatories to be located on the far side of the moon. The lack of intervention from terrestrial sources would be ideal not only for observing invisible parts of space, but also in the search for extraterrestrial intelligence.

In addition, Dr. Karan Gianni and Prof. Abraham Loeb – of the Laser Interferometer Gravity Observatory (LIGO) and the Harvard-Smithsonian Center for Astrophysics (CfA), respectively – recently suggested that the Moon also be an ideal place for a gravitational lunar lunar orbit. cosmology (GLOC).

NASA also plans to send a small satellite called the Dark Age Polarimetry Pathfinder (DAPPER) into lunar orbit in the coming years. This joint project between UC Boulder and the National Radio Astronomical Observatory (NRAO) will build on previous work by the Wilkinson Microwave Anisotropy Probe (WMAP) to study the early universe.

These and other proposals will have a chance to be implemented in the coming years. In addition to the return of astronauts to the moon by 2024, the long-term goal of Project Artemis is to create a program for “sustainable exploration of the moon.” Once this infrastructure is in place, permanent facilities can be built to help advance the science of space exploration!

Further reading: MacDonald Observatory,, arXiv


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