Watch: Seeing Beyond: The World of Telescopes
Tony Pallone | January 15, 2018The word telescope comes from the ancient Greek tele, or "far," and skopein, "to see." In this edition of the Engineering360 news brief, we'll look at some of the most interesting things happening in the world of seeing far beyond our own.
Mirror-making for the GMT
Making mirrors for what will be the world's largest telescope – the Giant Magellan Telescope, or GMT – is no small feat. A team at the University of Arizona cast the first of its seven mirrors in 2005, and construction is not expected to be finished until 2025. Each mirror costs $20 million to build, and involves more than 17,000 kilos of special glass that is placed into a 15-metric ton ceramic structure – one chunk at a time. The glass is slowly melted and continuously spun in a furnace to create a parabolic shape, then cooled by fractions of degrees over the course of three months. Shaping and polishing the mirror's front face to within 20 nanometers of perfection is a process that takes about 18 months. Once all the mirrors have been constructed, they will form a single optical surface of 24.5 meters, or 80 feet, providing 10 times the resolution of the Hubble Space Telescope. While the Hubble has been in low Earth orbit since 1990, the GMT will be a ground-based scope based at Las Campanas Observatory in Chile. There, it will be ideally situated to answer some of the biggest astronomical questions – including whether or not we are alone in the universe.
Testing for Space Readiness
In another painstaking process designed to ensure greater astronomical capabilities, approximately 100 days of cryogenic testing inside a thermal vacuum chamber has been completed for the James Webb Space Telescope. Removing air from the chamber, part of NASA's Johnson Space Center in Houston, took about a week; and cooling it, along with the scope and its science instruments, to the extreme cold temperatures of space took about 30 days. One of the tests performed inside the chamber was an alignment check of the 18 primary mirror segments, to ensure they would act as a single monolithic mirror in a space-like environment. Before spending most of the year in Houston, the scope also underwent vibration and acoustic testing at NASA's Goddard Space Flight Center in Greenbelt, Maryland, to ensure its readiness for the rigors of launching into space. In 2019, the telescope will be launched as an infrared space observatory where it, too, will probe the mysteries of our universe.
Fast Radio Bursts: A Message from Beyond?
Finally, in a mystery currently unfolding at the Robert C. Byrd Green Bank Telescope in West Virginia, a UC Berkeley team charged with looking for signs of intelligent life in the universe has been observing fast bursts of radio waves from a distant object. The bursts are so bright that they're visible across the universe. They are also nearly 100 percent linearly polarized, which indicates that their source is embedded in strong magnetic fields such as those around a massive black hole. The same phenomenon has also been observed by astronomers in the Netherlands, who detected the bursts with a telescope at the Arecibo Observatory in Puerto Rico. The source of the fast radio bursts, also known as FRBs, could be a highly magnetized, rotating neutron star, located in a dwarf galaxy about 3 billion light years from earth. It's also possible that bursts like these could be high-powered signals from an advanced civilization. While scientists admit this is a remote possibility, they have not ruled it out -- and have expressed interest in testing what they refer to as the "E.T." hypotheses for FRB-type transient signals in general.
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