The Extremely Large Telescope will be the largest optical and infrared
telescope in the world, producing images 16 times sharper than those from the
Hubble Space Telescope. It will make the most detailed studies of planets around
other stars, the first galaxies, in the universe supermassive black holes, and
the nature of the universe's Dark Sector. And we're gonna learn more about it
starting right now. Hello everyone, welcome back to Launch Pad Astronomy, I'm
Christian Ready, your friendly neighborhood astronomer. This video is
about the Extremely Large Telescope, or ELT. lt's origins date back to the late
1990s when the European Southern Observatory started to think about the
next generation of telescopes. They just finished building their Very Large
Telescope, or VLT. VLT consists of four 8-meter telescopes by combining the
light from all four unit telescopes. VLT can achieve a resolution equivalent to a
single 130 meter telescope. This technique is called "interferometry", and
while it does achieve high resolution, it simply cannot collect as much light as a
real telescope of that same aperture because there are far fewer reflecting
surfaces. In the early 2000s, ESO looked into the Overwhelmingly Large Telescope,
or OWL; a 100 meter telescope. The proposal carried a 1.5 billion euro
price tag, but it only had somewhere between a 75 to 90 percent chance of
success. Those are not good odds when spending that kind of money, so the
project was resized down to a 42 meters. A 42 meter telescope would have answered
the question of life, the universe, and everything, but its overall price tag was
only down to about 1.3 billion euro. In 2011 the telescope was resized again to 39.3 meters
by removing the outer ring of segmented hexagons. This brought the
price tag under 1.1 billion euro and all of the participating countries committed
to the project. Another way to keep the costs under control is to make sure that
the overall design is this compact as possible. This meant introducing a unique
five-mirror design which folds up the light path.
The primary mirror consists of 798 hexagonal segments. Each segment is about
1.4 meters across, but is only 50 millimeters thick. That makes the mirrors
lightweight and easy to produce. The secondary mirror is convex shaped. Tt's
4.2 meters in diameter and weighs 3.5 tonnes. It will
be the largest secondary mirror ever employed on a telescope, and the largest
convex mirror ever produced. The mirror will be shaped and polished to a
precision of 15 millionths of a millimeter. In order to achieve the
sharpest highest resolution images possible, ELT employs the most advanced
adaptive optics system ever developed, making use of a fourth mirror that is
2.4 meters across but only 2 millimeters thick. 8,000 magnetically levitated
actuators will readjust the surface of this mirror up to 1000 times per second
to correct for any distortions in the incoming light introduced by Earth's
atmosphere. Up to 8 high-powered lasers will create artificial guide stars for
the adaptive optics system to build up a 3d map of the atmospheric turbulence
between the telescopes mirror and the top of the sky. This system will provide
an improvement of about 500 in ELT's resolution, allowing ELT to resolve
images as sharply as the laws of physics allow. When ELT begins operations in 2024,
it will be equipped with two state-of-the-art first light instruments.
The High Angular Resolution Monolithic Optical and Near-infrared Integral field
spectrograph - or HARMONI - is a spectrograph that's designed to be set
up and calibrated very quickly, allowing ELT to achieve a kind of point-and-shoot
capability so that if something interesting happens they can stop what
they're doing and swing over and take a look at an exploding star, gamma-ray
burst, or anything else going boom in the night. It will be able to probe
high-redshift galaxies racing away from us in the expanding universe. It will
even have the ability to achieve one of ELT's highest priority scientific goals:
to directly analyze the atmospheres of extrasolar planets in
great detail. The Multi adaptive optics Imaging Camera for Deep Observations, or
MICADO, will be capable of diffraction-limited imaging at
near-infrared wavelengths. The sensitivity of this camera will be
comparable to the James Webb Space Telescope, but will have six times the
resolution. It will image the center of the Milky Way galaxy
in unprecedented detail, making ultra- sharp images of stars orbiting the
supermassive black hole lurking in our galaxy's core. Even though ELT is
designed to be as compact as possible for its aperture, its dome is the largest
constructed for a telescope, dwarfing every other observatory. The dome has to
be aerodynamic to keep a uniform wind flow over the telescope. A ventilation
system keeps the wind flowing over the telescope smooth, automatically opening
and closing to ensure a continuous laminar airflow over the mirrors. ELT
will be located at Cerro Armazones in Chile. This site was chosen in part for
its cool dark and dry skies but also because of its proximity to the Paranal
Observatory which is home to the VLT. This allows ELT to make use of
existing infrastructure, such as roads, electricity, and so forth. First light is
expected in 2024 at that time ELT will not just be the pinnacle of ground-based
astronomy, but will also stand as a testament to our curiosity to understand
the universe and our place in it. It will detect Earth-like planets from the
wobbling motions of their stars. It will directly image larger exoplanets and
even characterize their atmospheres. It will be able to detect water and organic
molecules in protoplanetary disks around stars in the making; a major step forward
in answering the question of are we alone and if life can exist beyond Earth.
It will explore the first objects in the universe, looking back through time to
study the first stars, the first galaxies, even the first black holes. It will help
us to understand how galaxies, including our own Milky Way, form and
evolve. It'll mark our deepest probe into the mystery of dark matter, and the
dark energy that accelerates the universe apart. ELT will give ESO much
deserved bragging rights as the largest eye on the sky, but it's hardly a
zero-sum game. ELT represents an international collaboration not just
between countries and institutions, but also between the other next-generation
telescopes such as the Giant Magellan Telescope, the Thirty Meter Telescope, the
James Webb Space Telescope, and many more. Now if you'd like to learn more about
the next generation of telescopes that are under development, I have some links
to them which I'll provide for you both here on screen and in the description
below. And if you'd like to join me on this
journey through this amazing universe of ours, please make sure to subscribe and
ring the notification bell so that you don't miss out on any new videos. Until
we see you next time, I'm Christian Ready, and keep watching the skies.
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