You are here: Home / Instruments / James Webb Space Telescope - MIRI

James Webb Space Telescope - MIRI


The telescope

The James Webb Space Telescope (Webb) is the largest, most powerful telescope ever launched into space. Webb will reveal the Universe hidden to our eyes by observing infrared light, or what we would call heat, unveiling stars shrouded in clouds of dust, molecules in the atmospheres of other worlds, and light from the first stars and the earliest galaxies, peering back in time over 13.5 billion years. With its suite of state-of-the-art instruments, Webb will push the frontiers of our knowledge of the Solar System, of how stars and exoplanets form, and of galaxy formation and evolution.

Webb is a collaboration between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA). The telescope launched on an Ariane 5 rocket from Europe’s Spaceport in French Guiana in December 2021. From there it embarks on a month-long journey to its destination orbit around the second Lagrange point, about one and a half million kilometres from Earth. In the first month after launch, Webb will unfold its sunshield, which is the size of a tennis court. The sunshield effectively blocks the heat of the Sun, keeping the telescope and its instruments cool at -233 degrees Celsius, ensuring that they emit no infrared radiation of their own that would interfere with the signals from observed astronomical objects. In the next few months Webb will continue with alignments and calibration, so the full science operations can start six months after launch.

The telescope has a 6.5-metre primary mirror, made up of 18 hexagonal segments, so big it is folded origami-style to fit in the Ariane 5 rocket. The mirror can detect the faint light of distant stars and galaxies with a sensitivity a hundred times greater than that of the Hubble telescope, which ‘only’ has a mirror of 2.4 metre. Webb is so sensitive, it is said it could detect the heat signature of a bumblebee on the moon.

The science

The James Webb Space Telescope will be a giant leap forward in our quest to understand the Universe and our origins. Webb will examine every phase of cosmic history: from the first luminous glows after the Big Bang to the formation of galaxies, stars, and planets to the evolution of our own solar system.

JWST's investigations will cover questions such as: What did the early Universe look like? When did the first stars and galaxies emerge? How did the first galaxies evolve over time? What can we learn about dark matter and dark energy? How and where do stars form? What determines how many of them form and their individual masses? How do stars die and how does their death impact the surrounding medium? Where and how do planetary systems form and evolve?

The instruments

The telescope will carry four scientific instruments: the Near-Infrared Camera NIRCam, the Near-Infrared Spectrograph NIRSpec built by ESA and NIRISS build by the Canadian Space Agency, and the Mid-infrared Camera and Spectrograph MIRI. Researchers of the KU Leuven Institute of Astronomy, together with other Belgian partners, have contributed in all stages of the MIRI instrument development. Besides supporting the development of the instrument, Belgian researchers also participated in the original discussions that defined the JWST/MIRI science cases, which, in turn, informed the instrument technical requirements and design.




The MIRI instrument

The MIRI instrument will operate between wavelengths of 5 to 27 microns, a region that is difficult or impossible to observe from the ground. It consists of two actively cooled subcomponents, an imager and an Integral Field Unit (IFU) spectrograph, and an on-board calibration unit. The imager provides broad and narrow-band imaging, a coronagraph and low resolution slit spectroscopy (R~100) using a 1024x1024 pixels (Sivas) array. The pixels scale will be 0.1". The integral field spectrograph will provide simultaneous spectral and spatial data on a field of view of 3.6" by 3.6" to about 7.6." by 7.6" with increasing wavelength. The wavelength range it will operate in is 5-27 micron with a spectral resolution of about 3000.

The MIRI instrument was built by in international consortium of scientific institutes. Thanks to funding by the Belgian federal science policy office BELSPO via the ESA PRODEX programme, Belgian engineers and scientists played a key role in the development of the instrument. Belgian researchers also participated in the original discussions that defined the JWST/MIRI science cases, which, in turn, informed the instrument technical requirements and design. The Centre Spatial de Liege (CSL) built the instrument control electronics box, and several opto-mechanical units with industrial partners Thales Alenia Space (Charleroi) and OIP Sensor Systems (Oudenaarde). At the Institute of Astronomy at KU Leuven, instrument scientists have been testing the MIRI instrument extensively in special test chambers simulating the space environment in laboratories in the UK, at NASA Goddard and NASA Johson Space centers. 

The MIRI team at the Institute of Astronomy at KU Leuven is part of the MIRI instrument test team that is responsible for the laboratory tests of the MIRI instrument (Verification Model and Flight Model).  Our team members designed, executed and analysed performance tests for the verification model and for the flight model in a series of dedicated test campaigns at the Rutherford Appleton Laboratories (UK) and the Goddard Space Flight Center (US).  Our team was also responsible for the MIRI Real Time View (RTV) workstation and software, the EGSE component that allows an on-line data analysis and verification of the success of the tests of the integrated instrument at the test facility of the Rutherford Appleton Laboratories (RAL).  The test team web-based collaboration platform is also hosted at our institute. The KU Leuven MIRI team was also responsible for the calibration of the MIRI instrument and data.








People involved

Wim De Meester, Rik Huygen, Bart Vandenbussche, Christoffel WaelkensPierre Royer, Yannis Argyriou

First JWST instrument MIRI Delivered to NASA

First JWST instrument MIRI Delivered to NASA

On May 9, 2012, the first instrument for the James Webb Space Telescope (JWST), was delivered to NASA for integration in the spacecraft. KU Leuven astronomer and MIRI Co-Principal Investigator Christoffel Waelkens and his team attended the handover ceremony in London, and are looking forward to the wealth of data the instrument is expected to produce after its launch in 2018.

First JWST instrument MIRI Delivered to NASA - Read More…