Japan representative of the Thirty Meter Telescope shares his thoughts on the challenges of TMT

With its increased sensitivity, TMT will see closer objects in greater detail, and see new, farther away objects that have never been observed before.

Masanori Iye, the Japan representative for the Thirty Meter Telescope (TMT), gave a talk at ‘Imiloa Astronomy Center of Hawai‘i last month.

The talk, entitled, “Scientific and Engineering Challenges of the Thirty Meter Telescope: A Perspective from Japan,” was part of a monthly series of public talks given at the center. ‘Imiloa is part of the University of Hawai‘i at Hilo campus.

In his talk, Iye, professor emeritus of the Subaru Telescope, compared the scientific and engineering challenges of the Subaru telescope to those of the planned TMT.

“It was my honor to have a chance to talk at ‘Imiloa Maunakea Skies,” says Iye. “Maunakea is so special for all of us who have a special love to the mountain. I am sure we shall be able to overcome eventually not just the scientific and engineering challenges but also the cultural [challenges].”

Subaru Telescope’s mirror

The evening began with a brief look at the night sky where the audience compared what is visible with the naked eye verses with a telescope.

Iye began by discussing the challenges with Subaru Telescope throughout its planning and construction.

Subaru is a unique observatory, as it pushed the limit of how large a single mirror could be constructed. Unique systems were implemented to correct for astigmatism with the mirror and innovations of adaptive optics technology was also developed to properly subtract out the adverse effects of the atmosphere.

TMT’s mirror

TMT’s mirror will be very different from Subaru’s mirror, as it is simply not possible to build a single mirror that large. However, the design of the mirror will be similar to M. W. Keck Telescopes’ in that it will use multiple segmented mirrors which are precisely designed and aligned to act together as one single large mirror.

Japan assumes the responsibility of building TMT’s main telescope structure using their experience of Subaru’s construction to guide them.

Japan is currently producing the mirrors for TMT, with the telescope requiring 492 mirrors total with an additional 82 spares; so far 164 of the 584 required mirrors have been produced.

It’s all about the magnitude

Astronomers use the term “magnitude” to describe how bright or faint an object is. The magnitude scale is often confusing as bright objects are low numbers, while fainter objects have higher numbers; for example, the sun has a magnitude of -26.7, while the star Hikianalia, also known as Spica, has a magnitude of 1.04 as it is much fainter than the sun.

TMT is projected to be sensitive to light as faint as 32 magnitude. For comparison, the human eye is sensitive to six magnitude while current telescopes are sensitive to 28 magnitude. Detecting light as faint as 32 magnitude would be the equivalent to seeing a firefly blink on the dark side of the moon.

With its increased sensitivity, the TMT will see closer objects in greater detail, and see new, farther away objects that have never been observed before.

As astronomers look farther away into the Universe they are also looking back in time, as it took so long for the light of distant objects to reach Earth. This will allow astronomers to study the new planets now being discovered around other stars, and gain a better understanding of the Cosmic Dawn of the universe and Earth’s own origins.


-Adapted from the ‘Imiloa Blog.

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