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Telescopes and space missions

Telescopes and space missions

European superscope reveals its three ‘first-light’ instruments

16 Oct 2015
Spectral view: METIS – an infrared camera and spectrograph

The design of the three “first light” instruments for the European Extremely Large Telescope (E-ELT) – the biggest ever optical/near-infrared telescope to be built – has been agreed upon by the European Southern Observatory (ESO), which recently signed agreements for their construction. For the E-ELT first phase – which will begin in 2024 – the superscope will be equipped with the Mid-infrared E-ELT Imager and Spectrograph (METIS); the Multi-Adaptive Optics Imaging Camera for Deep Observations (MICADO); and the High Angular Resolution Monolithic Optical and Near-infrared Integral field spectrograph (HARMONI).

Located on the summit of Cerro Armazones in the Atacama Desert, in northern Chile, the 39 m main mirror of the E-ELT will gather 13 times more light than the largest optical telescopes operating today. Indeed, the collaboration says that the telescope’s advanced adaptive optics – which adjust the telescope’s deformable mirrors in real time to correct for distortions caused by Earth’s atmosphere – will allow it to take images that are 16 times sharper than those from the Hubble Space Telescope. The colossal telescope will enable astronomers to address fundamental cosmology questions by measuring the properties of stars and galaxies, probing the nature of dark matter, and studying Earth-like exoplanets and young galaxies in great detail.

Eye on the deep sky

MICADO, the E-ELT’s first camera, is being developed by a group of European institutes, led by the Max Planck Institute for Extraterrestrial Physics. The sensitivity of the near-infrared camera will be comparable to the James Webb Space Telescope, but with six times the resolution. It will be able to detect incredibly faint astronomical objects, and reveal the structure of galaxies and nebulae in unprecedented detail. MICADO’s astronomic precision should allow scientists to track the movement of objects that currently appear static, such as star clusters and even individual stars within clusters.

“If we look at two stars on the detector, we will be able to measure their position so precisely and so repeatedly, that if we make the same measurement a year later, we can see whether they have moved apart or closer together by about 1/5 of a micron,” explains Richard Davies, from the Max Planck Institute.

Spectral point-and-shoot

HARMONI – a spectrograph that will split visible and near-infrared light into its component wavelengths – will be built by a European consortium, led by the University of Oxford. Instead of taking spectral data from a single narrow split, like most spectrographs, HARMONI will use a technique known as “integral field spectroscopy” to obtain spatially resolved spectra from across the sky. Light will be split across 152 ”slitlets”, each of which will analyse its spectrum at 214 points. This means that more than 30,000 spectra will be obtained at the same time, making HARMONI much faster and more efficient than conventional instruments.

“HARMONI has been designed to be a workhorse instrument,” says Niranjan Thatte from Oxford. “We have designed it to be easy to calibrate and operate, providing the E-ELT with a ‘point-and-shoot’ spectroscopic capability.”

Complementary views

METIS will complement HARMONI and MICADO by providing imaging and medium-resolution spectroscopy across the longer wavelengths of the mid-infrared spectrum – from 3–19 μm – and high-resolution integral field spectroscopy at wavelengths of 3–5.3 μm. It will make full use of the E-ELT’s main mirror to focus on five goals: the physical and chemical properties of exoplanets, proto-planetary discs and planet formation, the history of the solar system, the growth of supermassive black holes, and high-redshift galaxies.

A group of European institutes, led by Leiden University, will develop the METIS instrument. Bernhard Brandl from Leiden told physicsworld.com that the project “is obviously a big challenge, but everyone is excited to be working on the project and we have received a lot of support from the university and the astronomical community in the Netherlands”.

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