The Extremely Large Telescope (ELT) will be located on the summit of Cerro Armazones, about 3,046 metres high in the Chilean Atacama Desert, surrounded by stunning views of the plains below.
In around three years, the world's largest optical telescope, the Extremely Large Telescope (ELT) of the European Southern Observatory (ESO), is scheduled to go into operation in the Chilean Atacama Desert. Equipped with a variety of instruments that can be switched between within minutes, the ELT will enable Earth-based views of the universe at unprecedented depths. Two of these instruments, in whose development numerous Austrian experts are also involved, have now passed the final design review and thus reached an important milestone: The "Multi-AO Imaging Camera for Deep Observations" (MICADO), a powerful high-resolution camera for the ELT, completed the design phase in the summer; the "Mid-infrared ELT Imager and Spectrograph" (METIS) already in May. Both instruments are scheduled to go into operation when the ELT launches or shortly thereafter.
Contributions to research on exoplanets
METIS, a camera and spectrograph in one, is designed for observation in the mid-infrared range and is therefore ideal for studying cold objects or objects enshrouded in dust. "While very hot objects such as our sun mainly emit visible light, colder objects such as planets or dust clouds radiate mainly in the mid-infrared range. By analyzing the light in this frequency range, METIS will study how stars and planets form in dust and gas clouds and can look through the dust in the center of galaxies to study their supermassive black holes," explains Kieran Leschinski from the Institute of Astrophysics at the University of Vienna. He is part of the Austrian group of experts, which includes the University of Vienna, the University of Innsbruck, the Johannes Kepler University (JKU) Linz and the RICAM Linz of the Austrian Academy of Sciences (ÖAW).
In addition, METIS is expected to make exciting contributions to exoplanet research by observing small, rocky exoplanets and studying the temperature, weather and chemical composition of their atmospheres in the search for habitable worlds. "With METIS, we are pursuing a broad spectrum of scientific goals, from exploring the formation history of our solar system to looking into the center of galaxies and studying their enigmatic supermassive black holes. The scientific focus of METIS is on studying planet formation disks and recently formed - as well as nearby - exoplanets," says Norbert Przybilla, professor at the Institute of Astro- and Particle Physics at the University of Innsbruck.
Observing distant galaxies
The second instrument whose design process was recently completed is the "Multi-AO Imaging Camera for Deep Observations", or MICADO for short. MICADO will provide high-resolution images of the universe and reveal the formation mechanisms of distant galaxies. The development of MICADO was primarily focused on the desire for maximum precision and stability in order to achieve the required high sensitivity, resolution, astrometric accuracy and coverage of a wide wavelength range. To ensure this, the instrument will be of impressive size: around six meters high, it will weigh no less than 20 tons.
The heart of the instrument, like that of METIS, will be housed in a cryostat that keeps it cool so that it can operate effectively in the near infrared without interference from other heat sources. This will make it possible to obtain high-resolution images of the Universe that reveal the detailed structures and formation mechanisms of distant galaxies and allow astronomers to study individual stars and star systems in nearby galaxies, as well as planets and their formation outside our solar system. In addition, MICADO will be a uniquely powerful instrument for exploring environments where gravitational forces are extremely strong, such as near the supermassive black hole at the center of our galaxy, the Milky Way.
"Earth-based astronomical observations are disturbed by turbulence in the Earth's atmosphere and can also be perceived with the naked eye as the stars blinking. By developing algorithms to correct this turbulence using deformable mirrors, the team at JKU Linz and at RICAM of the ÖAW is making a significant contribution to being able to take sharp images of distant celestial objects," explains Ronny Ramlau, Professor at the Institute for Industrial Mathematics at Johannes Kepler University Linz and Scientific Director at RICAM Linz/ÖAW.
Further expert opinions:
Kieran Leschinski, Institute of Astrophysics at the University of Vienna: "The Extremely Large Telescope (ELT) will be the most powerful optical/infrared telescope ever built. With its enormous 39-meter primary mirror, the ELT will make it possible to observe the faintest and most distant objects in the cosmos - from the first galaxies that formed after the Big Bang to potentially habitable exoplanets orbiting nearby stars. Our team here in Austria is responsible for developing the software for MICADO and METIS, which will enable astronomers to extract groundbreaking scientific results from the raw data coming directly from the telescope's instruments."
Werner Zeilinger, Institute of Astrophysics at the University of Vienna: "The spatial resolution achieved by the ELT is so high that a Lego figure can be observed on a space station. However, at such a high resolution, even the smallest turbulence in the atmosphere causes the images to blur - similar to looking at an object at the bottom of a swimming pool. To counteract this effect, the Extremely Large Telescope (ELT) integrates several flexible mirrors that can deform hundreds of times per second and thus eliminate atmospheric distortions in real time. This will enable the ELT to take significantly sharper images than the Hubble Space Telescope."
Manuel Güdel, Professor at the Institute of Astrophysics at the University of Vienna: "METIS will revolutionize our understanding of planetary systems. Its high-resolution infrared images and spectra will make it possible to study exoplanets and their atmospheres in unprecedented detail. This state-of-the-art instrument will also help identify potentially habitable worlds and bring us closer to answering the profound question of whether life exists outside our solar system. METIS will also provide insights into star formation and the conditions around young stars, which in turn drive planet formation and evolution."
Wolfgang Kausch, Institute for Astro- and Particle Physics at the University of Innsbruck: "In order for MICADO to achieve the required high sensitivity, resolution, astrometric accuracy and coverage of a large wavelength range in the ELT environment, the instrument will weigh no less than 20 tons and be six meters high."
Roland Wagner, RICAM Linz, ÖAW: "Within MICADO, software is being developed at the RICAM of the ÖAW and at the JKU Linz to evaluate image quality using the so-called point spread function. This will enable the properties of the observed stars to be determined more precisely than before when analyzing the images. The method for this is currently being tested on data from existing telescopes."
Andreas Obereder, Institute of Industrial Mathematics, JKU Linz: "Controlling deformable mirrors for the ELT is a particular challenge due to the size of the primary mirror. In order to compensate for the resulting effects as best as possible, the commands for the deformable mirror are calculated from the data of a pyramid sensor using a newly developed algorithm. In the simulation, we thus obtain better results than previous methods."