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The launch of a new era: Leiden and the James Webb telescope (Part I)

After 25 years, this December will finally see the launch of the long-awaited James Webb space telescope (JWST). Leiden astronomers are watching with great excitement: not only were they involved in the construction of important instruments on board, but the telescope will also reveal many new secrets of the universe, both foreseen and unforeseen.

Part I: How the Dutch helped build one of the most important instruments on board.

A key role is reserved for Leiden professor Ewine van Dishoeck. She has been involved with JWST from the beginning. In 1997, van Dishoeck was part of a small group of scientists that suggested the idea of sending a hyper-sensitive infrared instrument along. This became the Mid-InfraRed Instrument (MIRI): an infrared camera and spectrometer for which the Netherlands developed a large part of the optics and which will soon enable us to look right through cosmic dust.

A Dutch ‘passenger’ on board

Professor of Infrared Astronomy Bernhard Brandl was closely involved in the construction of MIRI. ‘Unlike the other scientific instruments aboard, MIRI has not been designed and built by space agencies NASA and ESA, but by an international consortium of institutes,’ he says. ‘The Netherlands Research School for Astronomy (NOVA) was one of them.’

Brandl took part in many discussions and interactions, and also participated in the first test campaigns of the instrument. ‘I guided the team that developed the medium-resolution spectrometer of MIRI,’ he says. A spectrometer catches the light emitted by an object in space and separates it into different wavelengths, creating a ‘fingerprint’ that contains key information on these astronomical objects. Brandl: ‘MIRI will be able to “see” light in the mid-infrared spectrum, with wavelengths invisible to the human eye.’  

Video: NOVA builds the heart of MIRI

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A giant leap forward

According to Brandl, MIRI is a giant leap forward. ‘Such a powerful infrared spectrometer in space will be unique. It will enable us to look at cooler objects, which emit at these longer wavelengths. We will learn so many new things from the atmospheres of nearby exoplanets, to the evolution of distant galaxies. Furthermore, MIRI will allow us to analyse the spectra of different light points taken at once, which provides new research opportunities that would not have been possible with a classical spectrometer.’

As the successor to the beloved Hubble Space Telescope, Webb will have much more light collecting power – which equals more sensitivity and sharper images. ‘Webb’s angular resolution and sensitivity puts it way ahead of previous missions,’ Leiden professor Marijn Franx points out. He was involved in the development of another instrument on Webb: NIRSPEC.

Ready, set, launch

The James Webb Telescope is set for launch in December aboard an Ariane 5 rocket from the ESA launch facility in Kourou, French Guiana. As this site is close to the equator, the speed of the Earth’s rotation gives the launchers an extra boost. The 1.5 million kilometre journey takes about a month. Then, Webb will arrive at its new destination, where it will provide us with unforeseen space details for at least five, but hopefully ten years. 

How are Earth-like planets formed?

As remuneration for their contribution, researchers involved in developing Webb will receive guaranteed observation time. Van Dishoeck wants to use her share to study the composition of the gas and dust in disks in which new planets are being born. This can then be compared with that of atmospheres of mature exoplanets, which are planets around stars other than our Sun. 'Compounds such as water, carbon dioxide and methane can only be observed in the infrared or from space,’ she explains to the Dutch Financieel Dagblad. ‘And thanks to MIRI, Webb will be able to pick up even the faintest infrared light.’

The composition of these atmospheres tells us more about the history of the formation of planets, but also, for example, whether there are planets that are similar to Earth or that contain more or less water and other building blocks for life compared with our own home planet.

The MIRI instrument

The distant past

Franx will search for galaxies in the early Universe. ‘They’re very different from the ones we see nearby. The earliest stars and galaxies may be completely different from the stars like our Sun: they consist of hydrogen and helium, and may live only very briefly, to form black holes later. We hope that JWST can shed light on this special phase of the universe. Having more clues to questions like this can help us better understand the evolution of the Universe and the future of galaxies like our own Milky Way.’ 

Experience the launch in Leiden

Exciting news! On 25 December, James Webb will finally be launched into space. One day before, on Friday 24 December, Leiden astronomers Ewine van Dishoeck and Bernhard Branl will give lectures on Webb between 11.00-12.00 hrs. Ewines talk will be in Dutch, Bernhards English lecture will start at 11.30.
The lectures will be streamed via YouTube. The launch itself can be followed via a joint NASA-ESA webcast.

More information can be found in our agenda.

Webb in miniature

Going for a walk during the lockdown? Rijksmuseum Boerhaave has a 1:10 scale model of Webb on display. It’s placed in the foyer so it’s visible from the street side. And when our Faculty opens again, your more than welcome to check out our -slightly smaller 1:20 JWST model at the ground floor of the Huygens lab/Oort building, just in front of the Sitter lecture hall.

More information can be found in our agenda.

Headerphoto: The deployed primary mirror of NASA's James Webb Space Telescope looks like a spring flower in full bloom. Credits: NASA/Desiree Stover

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