News / Science & Technology

'Super-Giant' Telescope Mirrors Cast in Arizona

Artist drawing of the Giant Magellan Telescope under a starry night sky (Giant Magellan Telescope)
Artist drawing of the Giant Magellan Telescope under a starry night sky (Giant Magellan Telescope)
Rick Pantaleo
Scientists working at the University of Arizona’s Seward Observatory Mirror Lab have begun casting the third of seven mirrors for the Giant Magellan Telescope (GMT) now under construction in Chile.
 
The GMT, when complete, will be one of the next class of super-giant earth-based telescopes that scientists say promise to revolutionize our view and understanding of the universe.
 
According to those associated with the project, the GMT will have a resolution 10 times greater than the Hubble Space Telescope.
 
Like the first two mirrors that have already been made for the giant telescope, the third mirror it is being cast inside a special rotating furnace located in a lab beneath the University of Arizona football field. The Seward Observatory Mirror Lab is said to be the only facility in the world where mirrors of the size to be used in the GMT can be made.
 
Workers at Steward Observatory Mirror Lab prepare the rotating furnance in which the GMT mirror was cast. (Steward Observatory Mirror Lab/University of Arizona)Workers at Steward Observatory Mirror Lab prepare the rotating furnance in which the GMT mirror was cast. (Steward Observatory Mirror Lab/University of Arizona)
x
Workers at Steward Observatory Mirror Lab prepare the rotating furnance in which the GMT mirror was cast. (Steward Observatory Mirror Lab/University of Arizona)
Workers at Steward Observatory Mirror Lab prepare the rotating furnance in which the GMT mirror was cast. (Steward Observatory Mirror Lab/University of Arizona)
To prepare the mirror for casting, twenty tons of E6 borosilicate glass chunks were carefully placed into a special mold set inside of the furnace. The Lab’s furnace was started up on August 19, at 1400 UTC, with a rotating speed of 4.9 revolutions per minute.  It reached a high temperature of 1,165 C at 1649 UTC on Saturday.
 
The cooling and hardening process on the latest mirror will begin on Thursday – August 29 – when the furnace’s internal temperature is at 530 C. Officials at the at the University of Arizona say that this cooling-down phase is a very gradual process that should take the mirror down to room temperature by Nov. 19.
  
The lab team is planning to remove the mirror from its mold around the end of November. After it’s removed from the mold, the mirror will then undergo a thorough inspection. Those involved with this project won’t know if their casting efforts are successful until after the inspection is completed.
 
Once the mirror is successfully inspected, the next step toward completion will be an extensive and precise polishing process. The first of the seven mirrors was cast in 2005 and the polishing process was completed in 2012.  The second mirror was cast in 2012 and is now being polished.
  
Each of the seven primary mirrors will be 8.4 meters in diameter and weigh about 20 tons, but when polished and finished, the mirror surface will be smooth to within a twentieth of a wavelength of light.
 
Construction in Chile
 
When all seven mirrors have been finished, they will be transported to where the Giant Magellan Telescope is being constructed: atop a peak – 2,590.8 meters elevation - of the Andes Mountains near several existing telescope facilities at Las Campanas, Chile.
 
Six of the GMT’s mirrors will be arranged as segments around the seventh forming a virtual single mirror array that will be 24.5 meters in diameter.
 
The mirror of the Hubble Telescope, which has imaged some of the most spectacular views of the universe, on the other hand, measures about 2.5 meters from one edge to the other.
 
The Giant Magellan Telescope is scheduled to begin its science operations in 2020.
 
Those involved with its construction and operation say that it will give astronomers the opportunity of getting answers some of the most pressing questions about the universe – “including the detection, imaging, and characterization of planets orbiting other stars, the nature of dark matter and dark energy, the physics of black holes, and how stars and galaxies evolved during the earliest phases of the universe.”
 
“Astronomical discovery has always been paced by the power of available telescopes and imaging technology. The GMT allows another major step forward in both sensitivity and image sharpness” said Peter Strittmatter, director of Steward Observatory. “In fact, the GMT will be able to acquire images 10 times sharper than the Hubble Space Telescope and will provide a powerful complement not only to NASA’s 6.5-meter James Webb Space Telescope (JWST), but also to the Atacama Large Millimeter Array (ALMA) and the Large Synoptic Survey Telescope (LSST), both located in the southern hemisphere.”
 
Overcoming atmospheric distortion
 
Space telescopes like the Hubble and forthcoming James Webb Space Telescope normally have an advantage over earth-based telescopes because they are able to make their observations outside of Earth’s atmosphere. That allows the space telescopes to take images that are free of distortion created by our atmosphere.
 
So how can an earth-based telescope take images of the cosmos with the clarity of or better than space telescopes? An international team of astronomers just may have the answer.
 
In related news, astronomers have developed a new type of optical system that may allow scientists, using Earth-based telescopes to take sharper images of the night sky than ever before.The developers say their new optical system can counteract the blurring effects of the atmosphere by floating a very thin curved glass mirror that vibrates a thousand times per second  on a magnetic field that is set about nine meters above the telescope's primary mirror. The latest version of this new system, called MagAO for "Magellan Adaptive Optics” has been put into place at the Magellan II 6.5 meter telescope in Chile.​
 
The MagAO system should give 17 times the resolution of telescopes without it.


"As a result, we can see the visible sky more clearly than ever before," said Laird Close of the University of Arizona. "It's almost like having a telescope with a 21-foot mirror in space."
 
According to its developers, as it was being tested and received its “first light” – first use – the MagAO has been already making important scientific discoveries.

You May Like

Sydney Hostage-taker Failed to Manipulate Social Media

Gunman forced captives to use personal Facebook, YouTube accounts to issue his demands; online community helped flag messages, urged others not to share them More

UN Seeks $8.4 Billion to Help War-Hit Syrians

Effort aimed at helping Syrians displaced within their own country and those who've fled to neighboring ones More

Who Are the Pakistani Taliban?

It's an umbrella group of militant organizations whose objective is enforcement of Sharia in Pakistan 'whether through peace or war' More

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Will Pakistan School Shooting Galvanize Pakistan Against Extremism?i
X
Ayesha Tanzeem
December 17, 2014 11:54 AM
The attack on a military school in Pakistan’s northwest city of Peshawar left 141 dead, including 132 children. Strong statements of condemnation poured in from across the world. The country announced three days of mourning, and the leadership, both political and military, promised retribution. VOA's Ayesha Tanzeem looks at how likely the Pakistani government is to clamp down on all extremist groups.
Video

Video Will Pakistan School Shooting Galvanize Pakistan Against Extremism?

The attack on a military school in Pakistan’s northwest city of Peshawar left 141 dead, including 132 children. Strong statements of condemnation poured in from across the world. The country announced three days of mourning, and the leadership, both political and military, promised retribution. VOA's Ayesha Tanzeem looks at how likely the Pakistani government is to clamp down on all extremist groups.
Video

Video ‘Anti-Islamization’ Marches Increase Tensions In Germany

Anti-immigrant rallies in Germany have been building in recent weeks, peaking Monday night in the city of Dresden where tens of thousands of people turned out to demonstrate against what they call the ‘Islamization’ of the West. Germany has offered asylum to more Syrian refugees than any other country, and this appears to have set off the protests. Henry Ridgwell reports from London.
Video

Video Aceh Rebuilt Decade After Tsunami, But Scars Remain

On December 26, 2004 there was an earthquake in the Indian Ocean so powerful it caused the Earth’s axis to wobble a few centimeters. Onshore on the island of Sumatra, the resulting tsunami was devastating. A decade later, VOA Correspondent Steve Herman reports from Banda Aceh, Indonesia, where although there is little remaining evidence of the physical devastation, the psychological scars among survivors remain.
Video

Video Refugees Living in Kenya Long for Peace in the Home Countries

Kenya is host to numerous refugees seeking safe haven from conflict. Immigrants from Somalia face challenges in their new lives in Kenya. Ahead of International Migrants Day (December 18) Lenny Ruvaga has more for VOA News from the Kenyan capital.
Video

Video Turkey's Authoritarianism Dismays Western Allies

The Turkish government has been defiant in the face of criticism at home and abroad for its raids targeting opposition media. The European Union on Monday expressed dismay after President Recep Tayyip Erdogan lashed out at Brussels for criticizing his government's action. Turkey's bid to be considered for EU membership has been on hold while critics accuse the NATO ally of increasingly authoritarian rule. Zlatica Hoke reports.
Video

Video US-China Year in Review: Hong Kong to Climate Change

The United States is pushing for a code of conduct to resolve territorial disputes in the South China Sea as it works to improve commercial ties with Beijing. VOA State Department correspondent Scott Stearns reports on a year of U.S. policy toward China from Hong Kong to climate change.
Video

Video Japanese Leader’s Election Win Raises Potential for Conflict with Neighbors

Japan’s Prime Minister Shinzo Abe and his allies easily won a two-thirds majority in parliament Sunday, even though the country has slipped into recession under his conservative policies. VOA’s Brian Padden reports from Seoul, that the prime minister’s victory will empower him to continue economic reforms but also pursue a nationalist agenda that will likely increase tensions with Japan’s neighbors.
Video

Video Nuba Mountain Families Hide in Caves to Escape Aerial Bombings

Despite ongoing peace talks between Sudan's government and the rebel Sudan People’s Liberation Movement-North, or SPLM-N, daily aerial attacks continue in South Kordofan province’s Nuba Mountains. Adam Bailes was there and reports for VOA that government forces are targeting civilian areas, rather than military positions, with their daily bombardments.

All About America

AppleAndroid