Sure, the telescope you keep by your window is one of your favorite possessions. It opens up a universe of possibilities when pointed at the great vast night sky, allowing you to see the stars, planets, a multitude of distant galaxies as though they were at an arm’s reach. This isn’t to make you, or your telescope, feel inadequate, but your piece of equipment doesn’t hold a candle to this list of the world’s most advanced telescopes of the twenty-first century.
FAST: The Five-hundred-meter Aperture Spherical Telescope—Pingtang, China
Appropriately nicknamed the Eye of Heaven Telescope, the Five-Hundred-meter Aperture Spherical Telescope—or FAST—located in the remote hilled forest of the Guizhou province of southwest China, is the world’s largest and most advanced radio telescope, operated by the Chinese National Astronomical Observatory. Constructed in a natural karst depression, the five-hundred-meter aperture of FAST’s dish rests directly in the basin of the depression and is made up of 4,500 aluminum triangular panels that reflect radio information to the thirty ton feed cabin suspended one-hundred and forty feet above the dish. The feed cabin, which functions as an antennae, features a unique design in that its three-hundred meter area of focus can be mechanically rotated and positioned, via a pulley system connected to six support towers, to different areas of FAST’s dish. The dish itself is also able to be shaped to a target’s specifications, supported by over 2,200 actuators, which allows the adjustment of the dish’s parabola by vertically positioning the mesh support structure that holds the reflecting panels in place. Working together, this system allows for easier tracking of deep space objects, as both the dish and the feed cabin can move in real time.
Although FAST was declared fully operational just this past year, in January of 2020, the massive radio telescope saw first light on July 3rd, 2016. The telescope was first proposed in 1994, approved in 2007, and foundational construction began in 2011, after over four-hundred other locations were considered. In order to make room for the telescope, almost 10,000 people were relocated—an entire village out of the basin itself, and another 9,000 from the five mile radius surrounding the dish’s location—to create an area of radio silence that would not interfere with FAST’s operation. The construction of FAST cost around $180 Million, although many suspect this cost to be much higher, and that does not include the $269 Million that was spent on relocation and poverty support for those displaced during its construction, or the unknown amount of money that was spent modernizing the infrastructure in the surrounding area in hopes to attract tourism.
The goals of FAST are primarily the mapping of neutral hydrogen gas within the Milky Way, and the discovery and study of pulsars, of which FAST has discovered over one-hundred and twenty-three since its first light. FAST has also set its sights on the possible discovery of signals from extraterrestrial intelligence, as well as to improve deep-space communications to the outer edge of our solar system.
DKIST: The Daniel K. Inouye Solar Telescope—Maui, Hawaii
Originally named the Advanced Technology Solar Telescope before taking its namesake from Hawaii’s first native senator in 2013, the Daniel K. Inouye Solar Telescope—or the DKIST—on the Hawaiian island of Maui is the largest and most advanced solar telescope in the World. Operated by the National Science Foundation and the National Solar Observatory, the DKIST was built on the site of the Haleakala volcano at the Haleakala Observatory, a popular location for astronomical study thanks to the elevation, lack of nearby light pollution, and the clear dry air that helps to limit atmospheric interference.
Utilizing a Gregorian design, DKIST’s entrance aperture stands 10,023 feet above sea level, where it accepts photons from the Sun using an enormous alt-azimuth mount that allows it to follow the sun as it moves across the horizon. These photons then are reflected off of the four meter wide primary mirror, which has an adaptive optics system, meaning that the mirror can be reshaped in real time to counteract any atmospheric distortions or blurring. Because of the intense heat associated with the beam of sunlight that DKIST focuses, the photons are reflected by the primary mirror into a heat stop—a unique system of combined liquid and air cooling works to reduce the initial photon beam from four meters to one foot while reducing heat by ninety-five percent. Otherwise, the intense heat would soon disintegrate the telescope’s optical systems.
DKIST saw first light on December of 2019, the test images of which were released to the public the following month in January of 2020. After the contract to build DKIST was awarded in 2010, construction broke ground in 2013, and in 2020 DKIST was completed with the addition of instrumentation to allow the measuring of the Sun’s magnetic field. The total cost of the project was $344 Million.
The primary mission of DKIST is the continued measurement and analysis of the Sun’s ever-changing and variable surface, the magnetic fields of the Sun’s corona, as well as advancing solar imaging technologies. Through the use of both infrared and visual imaging, DKIST is able to produce images of the Sun at resolutions nearly three times that of the Swedish 1-m Solar Telescope. It is able to resolve featured of the Sun as small as only twelve miles, and the press release video that DKIST produced in 2019 shows detailed images of the Sun’s convection process over an area less than .01% of the Sun’s surface. This video clearly illustrates convection granules the size of Texas boil between the intergranular materials, as heated plasma rises to the surface and then sinks into the sun’s center over a remarkable period of only five minutes, showcasing the high levels of activity on the Sun’s surface.
GTC: Gran Telescopio Canarias—Isla de la Palma, Canary Islands, Spain
Built atop a volcanic mountain on La Palma in Spain’s Canary Islands off the coast of North Africa, the Gran Telescopio Canarias—or the GTC—holds the honor of being the largest infrared and single aperture optical telescope in the world. It is operated in a joint partnership between Spain, Mexico, and the University of Florida, and is part of the Roque de los Muchachos Observatory complex, which is host to sixteen other telescopes. Observing time within the partnership is divided based on financial contribution, so that Spain is able to utilize ninety percent of the telescopes operating time, while Mexico and the University of Florida are each allowed five percent of operating time.
The GTC’s 10.4 meter primary mirror is made up of thirty-six hexagonal panels, creating a reflective collecting surface area of just seventy-three square meters. Each of the mirror panels is able to move independently, along with the secondary mirror, to adjust to factors such as wind, temperature, and mechanical stress. The structure of the telescope is able to move both horizontally and vertically to adjust to the needs of its celestial target, no small feat for a unit that weighs over four-hundred tons. The preliminary designs for the GTC were inspired by the twin Keck telescopes at the Mauna Kea Observatories in Waimea, Hawaii, although many improvements were ultimately made, particularly with the knowledge that mechanical and scientific advancements will make ten-meter telescope design obsolete in the near future.
Initial planning for the telescope began in 1987, and the GTC was imagined as a joint venture between Spain and Great Britain, but after Britain stepped away from the project, Spain moved ahead on its own. The construction of telescope was a long and arduous process, hampered by the remote location and the difficult terrain and environment, taking seven years and costing $150 Million. The GTC saw first light in July of 2007, with only twelve of its mirror segments operating. Due to teething and other mechanical issues, it wouldn’t be until 2009 that the GTC began making scientific observations.
The GTC has a very broad astronomical mission, such as studying the nature of black holes, the formation of stars and galaxies in the early universe, distant planets around other stars, as well as the nature of dark matter and dark energy. In 2020 the GTC discovered the furthest black hole known to man, the center point of a very rare type of galaxy which emits gamma radiation, known as a blazar, about 12 Billion light years away. To put this into perspective, because light travels in such a way that the images we see reflects the state of an object as they were when the photons were initially released, the blazar that was seen exists at a point when the universe was less than 2 Billion years old.
SALT: Southern African Large Telescope—Sutherland, South Africa
Located on a large hilltop 1,798 meters above sea level in a remote region that sits between Africa’s two major weather streams, the South African Large Telescope— or SALT— has near ideal viewing conditions of seventy percent of the southern hemisphere’s sky. Appropriately nicknamed Africa’s Giant Eye in the Sky, SALT is in fact the largest telescope in the southern hemisphere. It is a multinational project between South Africa, Germany, Poland, India, the United States, the United Kingdom and New Zealand, with South Africa covering thirty percent of the total cost of the telescope’s operation. As with the GTC, the observing time granted within the SALT partnership is divided based on financial contribution. Construction of the telescope cost $20 Million, which is significantly less than the typical cost of a telescope of this magnitude, enabled by SALT’s cost efficient design.
SALT has a fixed altitude design, meaning that the primary mirror the telescope cannot be adjusted on a vertical axis, its zenith remaining fixed at fifty-three degrees, and that the telescope only rotates on the azimuth. To compensate for the limitations this design presents, the SALT’s prime focus moves above the stationary primary mirror on both vertical and horizontal axes, and moves to track an object. This design is unique to SALT and the Hobby-Eberly Telescope at the McDonald Observatory in Texas, which SALT’s design was inspired by, and enabled the telescope to be built at one-fifth the cost of typical telescopes of this scale. SALT’s eleven meter diameter primary mirror is made up of ninety-one individual hexagonal segments, each just over one meter across. Another advanced feature of SALT is its ability to be controlled remotely, for which state of the art ultra-high speed lines that enable international control and communication at one gigabyte per second.
Construction of SALT began in 2000, and the telescope achieved first light in 2005, although it did not become fully operational and begin scientific observations until 2011. SALT’s primary mission is the study of black holes, the hunt for dark energy, quasars, the galactic structure of the Milky Way, supernovae, and distant galaxies, as well as enabling cost-effective research and study between an international community of astronomers while also encouraging technological advancement and development in South Africa. One of SALT’s most notable achievements was the discovery of the polar binary class of stars, which rotate around each other at a speed of one ration per hour and a half.
LBT: Large Binocular Telescope—Mount Graham, Arizona, United States
On Mount Graham’s Emerald Peak, high in the Pinaleno Mountains of southeastern Arizona, sits the Large Binocular Telescope—or, the LBT. The LBT is actually two telescopes working in unison, and is host to the world’s largest monolithic primary mirrors with an 8.4 meter diameter and weighing sixteen tons a piece, meaning that they are not segmented as is the case with the other telescopes on this list. Each of these mirrors share a common alt-azimuth mount, and the visuals that they pick up are combined to form a single image that would be equivalent to a single telescope having a visual area of 11.8 meters, which is where the telescope gets its name. Working together, the two primary mirrors can achieve resolution greater than that of the Hubble Space Telescope. The LBT was the first of the Extremely Large class of telescopes, and was also the first to utilize adaptive optics that are integrated directly in the secondary mirror, enabling the secondary to morph its shape over one hundred times in one second. In expectation of the next generation of telescopes that are currently being built, the EBT being used as a test subject for technologies that will be implemented in the European Extremely Large Telescope, and the Thirty Meter Telescope, both planned for a completion is the latter half of the 2020s.
The LBT is a joint project between Italian, German, and American universities, ultimately costing $120 Million to build. Originally planned in 1987 and known as the Columbus Project, the LBT was envisioned in celebration of the five-hundredth anniversary of Christopher Columbus’ discovery of the Americas, with first light in 1992. However, due to controversy surrounding LBT’s location in the Pinaleno Mountains, an area viewed as sacred by the San Carlos Apache Tribe, as well as environmentalists concerned about the population of Mount Graham Red Squirrels, the project was ultimately delayed for a number of years, until Congress intervened allowing the construction of the telescope to move forward. Construction began in 1996, and the LBT saw first light in 2005 through the use of only one of its two primary mirrors. It wouldn’t be until 2008 that the LBT would operate with binocular application of both primary mirrors.
The primary mission of the LBT is the advancement of Extremely Large Telescopes, which aim to have an aperture of over twenty meters, and to study the formation of the solar system. In 2008, the LBT discovered galaxy cluster 2XMM J0830, which was, at the time, the largest galaxy cluster known to man, existing 7.7 Billion light years from Earth. In 2015, while imaging star LkCa15, which rests 450 light years away, the LBT captured the first ever images of a new planet in formation.
The Future
As impressive as these telescopes might be, there are already plans to outclass them all with the advancement of the next generation of telescopes, the ELTs. The Giant Magellan Telescope, which will have an aperture diameter of twenty four and a half meters, utilizing a primary mirror array of seven eight and a half meter mirrors, and is expected to have a resolution seven times that of the Hubble Space Telescope, is expecting first light in 2029 at the Las Campanas Observatory in Chile. Then, there’s the Thirty Meter Telescope, the diameter of its mirror living up to its name, and comprised of four-hundred and ninty-two individual segments, expected for first light in 2027 at Mauna Kea Observatory in Hawaii. The largest of the planned ELTs, the European Extremely Large Telescope is planned for a first light in 2025, and will feature a unique design utilizing five mirrors, with the primary mirror reaching an aperture of 39.3 meters and a resolution seventeen times greater than that of the Hubble Space Telescope. And speaking of Hubble, its successor, the James Webb Space Telescope is planned for launch in October of 2021, and will have a light collecting area over six times as large as Hubble, and will operate 930,000 miles from earth, nearly twice the distance of the Moon.
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