Europe’s place on Webb
Led by the UK, European partners built one of JWST’s main instruments
MIRI (Mid Infrared Instrument) is the major European contribution to Webb, apart from the Ariane launch. A camera and spectrometer combined, it was designed and built by a 10-country European consortium led by the UK, in collaboration with NASA.
MIRI’s high spectral resolution enables it to identify a huge range of molecules in star-forming regions, protoplanetary discs and exoplanet atmospheres. The instrument’s principal investigator is Professor Gillian Wright of the UK Astronomy Technology Centre, Edinburgh.
“MIRI’s capabilities cannot be achieved by ground-based telescopes,” she says. “The Earth’s atmosphere is too efficient at blocking mid-infrared wavelengths. Uncooled telescopes on Earth also emit their own mid-infrared light; for them to do MIRI’s work would be like looking for a match with a telescope that’s on fire. Webb is cold and far beyond Earth’s atmosphere, making MIRI hundreds of times more sensitive than any other instrument like it.”
To be this sensitive, MIRI has to be cooled to 6.7°C above absolute zero, or –266.5 °C. Since JWST’s sunshield will only provide temperatures as low as –230°C, the instrument also has a cryo-cooler, which acts like a refrigerator. A set of four coronagraphs enables the study of extrasolar planets without being ‘blinded’ by the radiation of the planets’ host stars.
MIRI was Webb’s first instrument to be completed and was integrated with the JWST in the US in 2013, after a final round of tests at the Rutherford Appleton Laboratory in Oxfordshire.