. 24/7 Space News .
STELLAR CHEMISTRY
Sixth mirror casting brings Giant Magellan Telescope closer to completion
by Daniel Stolte for UA News
Tucson AZ (SPX) Mar 05, 2021

Engineers at the Richard F. Caris Mirror Lab hand-load chunks of glass into the mold. Almost 20 tons of glass are added this way before the lid will be closed and the furnace fired up to melt the glass.Richard F. Caris Mirror Lab, The University of Arizona

At 3 p.m. on March 5, a gigantic furnace will slowly start spinning underneath the stands of Arizona Stadium at the University of Arizona. Fire-engine red, massive in size and resembling a sci-fi version of a Dutch oven, the furnace is the only one of its kind, and its sole purpose is to produce the world's biggest and most advanced telescope mirrors.

During the process, nearly 20 tons (17.5 metric tons) of extremely pure borosilicate glass made by Ohara Corporation in Japan will become a honeycomb mirror measuring 27.6 feet (8.4 meters) across. The mirror is the sixth of seven segments that together will make up the primary mirror of the Giant Magellan Telescope, currently under construction in Chile's Atacama Desert. The telescope will see farther into the universe and capture more detail than any optical telescope before.

Arranged in a flower-like array, seven individual mirror segments will come together to form a primary mirror surface measuring 82 feet (25 meters) in diameter. Due to the primary mirror's large size and deep curvature, the shape of each outer segment is unlike any mirror ever made and required major innovations for polishing and measuring the surface.

Spin-casting is the first step of a four-year process to create each mirror. The other steps are carried out in other parts of the Mirror Lab, so up to four mirror segments can be manufactured in parallel.

"The spin-casting is undeniably the most spectacular part of the manufacturing process," said Buddy Martin, polishing scientist at the university's Richard F. Caris Mirror Lab. Martin explained that after the casting, the surface "roughness" is about 2.5 millimeters, or a tenth of an inch, on average.

"The polishing and constant measuring are what turn this amazing piece of glass into a mirror," he said. "By the time we finish polishing, it will be accurate to better than 25 nanometers. That's how smooth the surface has to be in order to make the sharpest possible images."

Glass That Flows Like Honey
It took engineers and technicians four months to build the mold that will form the sixth lightweight honeycomb mirror, and it took nine hours to cover the mold with glass. With the mold in place and the glass loaded, they closed the furnace's lid, which measures 33 feet (10 meters) in diameter.

The furnace began heating the glass on March 1 and will reach a peak temperature of 2,129 degrees Fahrenheit (1,165 degrees Celsius) at 2 p.m. on March 6. The day prior, the furnace will begin rotating at five revolutions per minute, so as the glass melts, it is forced outward and up the sides of the mold to form a curved surface. At peak temperature, the glass will take on the consistency of honey and slowly flow into the mold to form the honeycomb structure.

The mirror will then enter a monthlong "annealing" process, during which the molten glass will cool while the furnace spins at a slower rate in order to remove internal stresses and toughen the glass. During this period, the mirror must have a uniform temperature, which is achieved by cooling it very slowly for just over a month. It will take another month and a half to cool to room temperature. Once the mold has been removed, the mirror "blank" will then be ready for grinding and polishing to refine the surface.

Viewing Power 10 Times Greater Than Hubble
With the first two giant mirrors completed and placed in storage in Tucson, the sixth mirror joins three others in various stages of production at the Mirror Lab. The third mirror's front surface polishing process is less than a year from completion. The fourth mirror has completed rear surface polishing, and load spreaders are being attached to allow the mirror to be manipulated during operation. The fifth mirror was cast in November 2017, and the seventh mirror is expected to be cast in 2023. An eighth mirror segment will also be made and can be swapped in when another segment requires maintenance.

Once the Giant Magellan Telescope becomes fully operational, it will have a light collecting area of 3,961 square feet (368 square meters) - enough to see the torch engraved on a dime from nearly 100 miles away. It also will offer the widest field of view of any Extremely Large Telescope in the 30-meter (98-foot) class. The telescope's viewing power is 10 times greater than the famed Hubble Space Telescope and four times greater than the highly anticipated James Webb Space Telescope, expected to launch in late 2021.

In the late 2020s, the giant mirrors will be transported more than 5,000 miles to the Giant Magellan Telescope's future home at Las Campanas Observatory more than 8,000 feet (2,400 meters) above sea level. The site is known for being one of the best astronomical sites on the planet, with its clear skies, low light pollution and stable airflow. The southern hemisphere location allows the telescope to see the Milky Way's center, which is of great scientific interest because of the types of stars found there and the super-massive black hole that lies at the center of the galaxy.

UArizona's Richard F. Caris Mirror Lab has been making the world's most advanced telescope mirrors for almost 40 years, and for the last 24 years has made the world's largest mirrors. These unique mirrors are lightweight honeycomb structures with the ideal mechanical and thermal properties needed to hold their shape to an accuracy of 50 nanometers (2 millionths of an inch) through thousands of nights of telescope observations.

Each mirror casting is a marvel of modern engineering that is usually celebrated with a large in-person event with attendees from around the world. Due to the COVID-19 pandemic, the sixth mirror segment will be cast behind closed doors to protect the health of the 10-person mirror casting team.


Related Links
Giant Magellan Telescope
Stellar Chemistry, The Universe And All Within It


Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Monthly Supporter
$5+ Billed Monthly


paypal only
SpaceDaily Contributor
$5 Billed Once


credit card or paypal


STELLAR CHEMISTRY
Webb Telescope completes final functional tests to prepare for launch
Greenbelt MD (SPX) Mar 02, 2021
February marked significant progress for NASA's James Webb Space Telescope, which completed its final functional performance tests at Northrop Grumman in Redondo Beach, California. Testing teams successfully completed two important milestones that confirmed the observatory's internal electronics are all functioning as intended, and that the spacecraft and its four scientific instruments can send and receive data properly through the same network they will use in space. These milestones move Webb closer ... read more

Comment using your Disqus, Facebook, Google or Twitter login.



Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

STELLAR CHEMISTRY
NASA and Boeing Evaluating Launch Date for Orbital Flight Test-2

Mission Commander Thrives as 'Space Gardener'

Kentucky firm plans orbital mini space station in two years

Boeing Starliner test flight postponed

STELLAR CHEMISTRY
New rocket, Firefly's Alpha, may be ready to launch by April

Rocket Lab plans new Neutron rocket, intends to go public

Musk, Maezawa say moon mission is on track for 2023

India launches PSLV-C51 carrying Brazil's Amazonia-1 and 18 Satellites

STELLAR CHEMISTRY
Perseverance Hardware One Day after Landing

NASA Awards Mars Ascent Propulsion System Contract for Sample Return

Planetary science intern leads study of Martian crust

Ice frozen under Mars' surface offers major resource to aid future settlements

STELLAR CHEMISTRY
China has over 300 satellites in orbit

China tests high-thrust rocket engine for upcoming space station missions

China explores space with self-reliance, open mind

China begins assembly of Long March 5B to launch space station core

STELLAR CHEMISTRY
SpaceX scrubs 20th Starlink communications satellite launch

Josef Aschbacher is new ESA Director General

Apply now to the ESA Teach with Space Online Conference

SpaceX plans 20th Starlink launch Sunday evening from Florida

STELLAR CHEMISTRY
We're launching more than ever

Marshall Spinoffs increase 3D printing capabilities, tackle foot odor

L3Harris Technologies Awarded Second Year of Space Object-Tracking Modernization Contract

Microsoft sets stage for mixed-reality future

STELLAR CHEMISTRY
Three elder sisters of the Sun with planets

Organic materials essential for life on Earth are found for the first time on the surface of an asteroid

Earth has a hot new neighbour - and it's an astronomer's dream

MAROON-X embarks on its exoplanet quest

STELLAR CHEMISTRY
SwRI scientists image a bright meteoroid explosion in Jupiter's atmosphere

Solar system's most distant planetoid confirmed

Peering at the Surface of a Nearby Moon

A Hot Spot on Jupiter









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.