Casting begins for 5th mirror of largest telescope

Washington, Nov 4 : The casting process has begun for the fifth of seven mirrors that will make up the world's largest telescope, the Giant Magellan Telescope Organization said.

The GMT, which will be installed in the Chilean Andes and produce images that are 10 times sharper than those from the Hubble Space Telescope, will combine the light from seven 8.4-meter-wide (27.5-foot-wide) mirrors to create a telescope with an effective aperture 24.5 meters in diameter, Efe news reported.

The process of casting these giant mirrors involves melting nearly 20 tons of glass in a spinning furnace, the Giant Magellan Telescope Organization (GMTO) said in a press release.

The release added that after the glass disk cools it is polished into its final shape using technology developed by the University of Arizona (UA).

"The result of this high-precision process is a mirror that is polished to an accuracy of one-twentieth of a wavelength of light, or less than one-thousandth of the width of a human hair."

The project, inaugurated in 2015 and expected to be operational by 2021, will be used to study planets outside our solar system and analyze galaxy formation.

"We are thrilled to be casting the Giant Magellan Telescope's fifth mirror," GMTO President Robert N. Shelton said.

"The Giant Magellan Telescope project will enable breakthrough discoveries in astronomy, and perhaps entirely new fields of study. With the talents of the team at the University of Arizona and across our entire community, we are taking the next step towards completing the seven-mirror GMT."

The first GMT mirror was completed several years ago, while three others are at various stages of production at UA's Mirror Lab.