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

Ebola Brings Sickness, Fear, Anger

Cornell University Professor Stacey Langwick considers cultural, social aspects of outbreak More

British Fighters On Frontline of ISIS Information War

It’s estimated that several hundred British citizens are fighting for Islamic State alongside other foreign Jihadists More

Violent Quarantine Clashes Hamper Liberia's Struggle to Contain Ebola

Anger, misinformation and mistrust of government hampering efforts to contain the deadly virus More

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Gaza Conflict, Hamas Popularity Challenge Abbasi
X
Scott Stearns
August 21, 2014 9:20 PM
The Palestinian unity government of Mahmoud Abbas has failed to convince Hamas to agree to Egyptian-negotiated terms with Israel on a Gaza cease-fire. VOA State Department Correspondent Scott Stearns reports on what the Gaza conflict means for President Abbas, with whom U.S. officials have worked for years on a two-state solution to the Israeli-Palestinian conflict.
Video

Video Gaza Conflict, Hamas Popularity Challenge Abbas

The Palestinian unity government of Mahmoud Abbas has failed to convince Hamas to agree to Egyptian-negotiated terms with Israel on a Gaza cease-fire. VOA State Department Correspondent Scott Stearns reports on what the Gaza conflict means for President Abbas, with whom U.S. officials have worked for years on a two-state solution to the Israeli-Palestinian conflict.
Video

Video Nigeria's 'Nollywood' Movie Industry Rolls in High Gear

Twenty years after its birth in a video shop in Lagos, Nigeria's "Nollywood" is one of the most prolific film industries on earth. Despite low budgets and whirlwind production schedules, Nigerian films are wildly popular in Africa and industry professionals say they hope, in the future, their films will be as great in quality as they are in quantity. Heather Murdock has more for VOA from Lagos.
Video

Video UN Launches 'Biggest Aid Operation in 30 Years' in Iraq

The United Nations has launched what it describes as one of the biggest aid operations in 30 years in northern Iraq, as hundreds of thousands of refugees flee the extremist Sunni militant group calling itself the Islamic State. As Kurdish and Iraqi forces battle the Sunni insurgents, the fighting has forced more people to flee their homes. Kurdish authorities say the international community must act now to avert a humanitarian catastrophe. Henry Ridgwell reports for VOA from London.
Video

Video Cambodian American Hip Hop Artist Sings of Personal Struggles

A growing underground movement of Cambodian American hip hop artists is rapping about the struggles of living in urban America. Most, if not all of them, are refugees or children of refugees who came to the United States from Cambodia to escape the Khmer Rouge genocide of the 1970s. Through their music, the artists hope to give voice to immigrants who have been struggling quietly for years. Elizabeth Lee reports from Long Beach, California.
Video

Video African Media Tries to Educate Public About Ebola

While the Ebola epidemic continues to claim lives in West Africa, information technology specialists, together with radio and TV reporters, are battling misinformation and prejudice about the disease - using social media to educate the public about the deadly virus. VOA’s George Putic has more.
Video

Video Ferguson Calls for Justice as Anger, Violence Grips Community

Violence, anger and frustration continue to grip the small St. Louis suburb of Ferguson, Missouri. Protests broke out after a white police officer fatally shot an unarmed black teenager on August 9. The case has sparked outrage around the nation and prompted the White House to send U.S. Attorney Eric Holder to the small community of just over 20,000 people. VOA’s Mary Alice Salinas has more from Ferguson.
Video

Video Beheading Of US Journalist Breeds Outrage

U.S. and British authorities have launched an investigation into an Islamic State video showing the beheading of kidnapped American journalist James Foley by a militant with a British accent. The extremist group, which posted the video on the Internet Tuesday, said the murder was revenge for U.S. airstrikes on militant positions in Iraq - and has threatened to execute another American journalist it is holding. Henry Ridgwell has more from London.
Video

Video Family Robots - The Next Big Thing?

Robots that can help us with daily chores like cooking and cleaning are a long way off, but automatons that serve as family companions may be much closer. Researchers in the United States, France, Japan and other countries are racing to build robots that can entertain and perform some simpler tasks for us. VOA’s George Putic reports.
Video

Video In Ukraine, Fear and Distrust Remain Where Fighting has Stopped

As the Ukrainian military reclaims control of eastern cities from pro-Russian separatists, residents are getting a chance to rebuild their lives. VOA's Gabe Joselow reports from the town of Kramatorsk in Donetsk province, where a sense of fear is still in the air, and distrust of the government in Kyiv still runs deep.
Video

Video Five Patients Given Experimental Ebola Drug Said to Be Improving

The World Health Organization has approved the use of experimental treatments for Ebola patients in West Africa. The Ebola outbreak there is unprecedented, the disease deadly. The number of people who have died from Ebola has surpassed 1,200. VOA's Carol Pearson reports on the ethical considerations of allowing experimental drugs to be used.
Video

Video China Targets Overseas Assets of Corrupt Officials

As China presses forward with its anti-graft effort, authorities are targeting corrupt officials who have sent family members and assets overseas. The efforts have stirred up a debate at home on exactly how many officials take that route and how likely it is they will be caught. Rebecca Valli has this report.
Video

Video Leading The Fight Against Islamic State, Kurds Question Iraqi Future

Western countries including the United States have begun arming the Kurdish Peshmerga forces in northern Iraq to aid their battle against extremist Sunni militants from the Islamic State. But there are concerns that a heavily-armed Kurdistan Regional Government, or KRG, might seek to declare independence and cause the break-up of the Iraqi state. As Henry Ridgwell reports from London, the KRG says it will only seek greater autonomy from Baghdad.
Video

Video In Rural Kenya, Pressure Builds Against Female Circumcision

In some Kenyan communities, female genital mutilation remains a rite of passage. But activists are pushing back, with education for girls and with threats of punishment those who perform the circumcision. Mohammed Yusuf looks at the practice in the rural eastern community of Tharaka-Nithi.

AppleAndroid