A group of astronomers from The University of Texas at Austin have discovered that a telescope idea canceled by NASA a decade ago might be the key to solving an astronomical conundrum.
The team, led by NASA Hubble Fellow Anna Schauer, say the Lunar Liquid-Mirror Telescope (LLMT) proposed, and then shelved, by NASA in 2008 would be able to study the first stars in the universe.
The team will publish the results of their study in an upcoming issue of The Astrophysical Journal.
The very earliest stars
Schauer and her team performed new calculations showing that the LLMT, a liquid mirror telescope that was proposed as a lunar construction project, might be able to study stars ranging back even further than the first galaxies that will soon be observed by the James Webb Space Telescope (JWST) project.
"Throughout the history of astronomy, telescopes have become more powerful, allowing us to probe sources from successively earlier cosmic times—ever closer to the Big Bang," Volker Bromm, a theorist who has studied the first stars for decades, and a member of Schauer's team explained in a press release. "The upcoming James Webb Space Telescope [JWST] will reach the time when galaxies first formed."
"But theory predicts that there was an even earlier time, when galaxies did not yet exist, but where individual stars first formed — the elusive Population III stars," Bromm continued. "This moment of 'very first light' is beyond the capabilities even of the powerful JWST, and instead needs an 'ultimate' telescope."
The 'Ultimately Large Telescope'
The team believe this 'ultimate' telescope may well be the Lunar Liquid-Mirror Telescope (LLMT). Proposed in 2008 by a team led by Roger Angel of The University of Arizona, the LLMT project idea was scrapped after an analysis by NASA.
According to Niv Drory, a senior research scientist with UT Austin's McDonald Observatory, the science to support the earliest stars did not exist as recently as 2008, which may partly explain why the idea was shelved. "This telescope [the LLMT] is perfect for that problem," Drory said.
The proposed LLMT telescope, nicknamed by Schauer as the "Ultimately Large Telescope," would operate autonomously from the lunar surface and would have a mirror (100 meters) 3937 inch in diameter. The Moon construction would be powered by solar energy and would relay data to satellites in lunar orbit.
The telescope's mirror would essentially be a spinning vat of liquid, topped by a reflective, metallic liquid. The vat would spin continuously in order to keep the surface of the liquid in the correct paraboloid shape to allow it to work as a mirror.
Exploring our cosmic history
In order to observe the very earliest stars, the LLMT would be constructed inside a crater at the Moon's north or south pole and would stare at the same patch of sky continuously so as to collect as much light as possible.
"We live in a universe of stars," Bromm said. "It is a key question how star formation got going early in cosmic history. The emergence of the first stars marks a crucial transition in the history of the universe, when the primordial conditions set by the Big Bang gave way to an ever-increasing cosmic complexity, eventually bringing life to planets, life, and intelligent beings like us."
"This moment of first light lies beyond the capabilities of current or near-future telescopes. It is therefore important to think about the 'ultimate' telescope, one that is capable of directly observing those elusive first stars at the edge of time."
The team from The University of Texas is urging the scientific community to revisit the canceled NASA idea for a lunar liquid-mirror telescope on the Moon. In doing so, they say, we might uncover some of the crucial mysteries of the very early formation of the universe.