The Irish hands behind the world’s most powerful telescope

17 Dec 2021

The James Webb Space Telescope. Image: Desiree Stover/NASA

We spoke to Prof Tom Ray of DIAS who helped build the infrared instrument on the James Webb, a telescope he thinks can revolutionise the field of astrophysics.

On Christmas Eve 2021, the largest and most powerful telescope ever built, the James Webb Space Telescope, will launch into space to study the universe like never before. Key to its observations will be infrared technology developed with the help of scientists in Ireland.

Developed by NASA, the European Space Agency (ESA) and the Canadian Space Agency, the telescope named after the former NASA administrator will succeed the agency’s flagship Hubble mission to observe some of the most distant objects in the known universe.

The James Webb telescope is scheduled for launch on 24 December from the Guiana Space Centre in South America. Once launched, it will begin its 10-year journey in space observing early stars, galaxies and nearby dust clouds to better understand how they formed.

Improved infrared technology, developed with the help of scientists from the Dublin Institute for Advanced Studies (DIAS), will enable James Webb to see deeper into the universe than Hubble and help it to identify and study the atmospheres of potentially habitable exoplanets.

‘Revolutionise’ astrophysics

Unlike the Hubble telescope, which used near-UV, visible and near-infrared spectra to make observations, James Webb will use a lower frequency range, from long-wavelength visible light through mid-infrared, to observe ‘high redshift’ objects that were too old and distant for Hubble to observe.

“Essentially, the James Webb telescope will help us see further back in time than Hubble did because of the increased power and sensitivity provided by upgraded infrared technology,” Prof Tom Ray, director of cosmic physics at DIAS, told

Prof Tom Ray standing in front of the ALMA space telescope in the Atacama Desert, Chile. There is a blue sky above and large radio telescope dishes in the background.

Prof Tom Ray in front of the ALMA space telescope in the Atacama Desert, Chile. Image: DIAS

“The observations the telescope will collect will help scientists answer some of the big questions about the cosmos, such as: What did the early universe look like? How did the first galaxies evolve? And how and where do stars and planets form?” he said.

Ray is the co-principal investigator of the mid-infrared instrument (MIRI) on the telescope, which has a camera and spectrograph that can observe mid to long-infrared radiation. It also has a coronagraph designed to block out the light of a star, which is useful when observing exoplanets.

“With the help of MIRI, the James Webb telescope will revolutionise the field of astrophysics. Telescopes on the ground just can’t perform with the same level of detail as telescopes in space because the atmosphere comes in the way, making stars appear to twinkle,” he explained.

But to observe in the infrared without interference, the telescope will have to be in a very cold environment. This is why it will be deployed in space near the Sun-Earth L2 Lagrange point, almost four times the distance of the moon, which will keep it below -223 degrees Celsius.

The hardware contribution aside, scientists from DIAS are also involved in the software aspect of things, making sure the scientific community can make the most of the data collected once the James Webb is in action.

Dr Patrick Kavanagh, who is a software developer and member of the international MIRI team, will participate in the commissioning of the instrument at the Webb Mission Operations Centre in Baltimore, US early next year.

His role will involve analysis and simplification of the large amounts of data that will be gathered from the James Webb Telescope, which will help DIAS and Irish scientists in their astrophysics research for years to come.

DIAS on the international dais

This is not the first time DIAS has collaborated majorly with NASA. While DIAS scientists have been working on the James Webb telescope for at least 15 years, the Dublin institute was also involved in the Apollo programme, studying some of the first moon rock samples.

“It is testament to the platform DIAS holds on the international stage in astronomy and astrophysics that we have such strong Irish involvement in this project,” Ray said of the James Webb launch.

DIAS is now collaborating with the ESA on the Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) telescope, helping to build key instruments. ARIEL aims to observe at least 1,000 known exoplanets, studying their chemical composition and thermal structures.

A host of other national and international projects are in the DIAS pipeline, but the long-anticipated launch of the James Webb telescope, and DIAS’ key role in it, will be a significant achievement for years to come.

Ray told that he has high expectations for the telescope and is excited to see what comes out of its journey in space. “I’m 100pc sure we’ll be going ‘what the hell is that?’ at some point while looking through its lenses.”

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Vish Gain is a journalist with Silicon Republic