17 June 2021

A new space telescope, the most expensive ever constructed, is scheduled to be blasted into space on top of a rocket this October, with its sights to be set on the earliest era of deep time, when the universe’s first stars and galaxies were forming in the aftermath of the Big Bang. Billed as a replacement to the ageing Hubble Space Telescope, which was equally ground-breaking in its own day, the new James Webb Space Telescope has a 6.5 metre mirror, 7 times larger in area than Hubble’s 2.4 metre mirror. This increased sensitivity will allow it to see new details of the universe that elude all our existing telescopes.

Astronomers around the world are nervously anticipating the epochal moment when the first data begins to be beamed back from the telescope’s incredibly sensitive instruments. One of these astronomers is ARC Australian Laureate Fellow, Distinguished Professor Karl Glazebrook FAA, whose research group has been allocated a significant amount of time on the new telescope, which they will use to study the spectra of ancient galaxies.

‘I am passionate about the earliest galaxies, and the earliest stars,’ says Professor Glazebrook, who has spent much of his research career working with some of the world’s largest telescopes to peer into the first few billion years of the universe’s existence.

‘In recent years we have made great breakthroughs with detections of the earliest stars and galaxies using ground-based telescopes, but there are still many unknowns, fundamental questions about what galaxies and stars were doing at this early period of time.’

‘Even more exciting are the ‘unknown unknowns’ – the things that we can’t even predict. It’s possible that monstrous stars composed entirely of dark matter might have existed then, or other exotic types of massive star.’

Professor Glazebrook is one of only three Australian ‘Principal Investigators’ who have been successful in bidding for time to use the new space telescope, and he has also been part of a push to increase the high success rate of Australians who apply for time on the James Webb telescope.

‘Last year, our group held a training day – a ‘JWST Masterclass’ – for Australian astronomers on how to put together a proposal for James Webb, and to ensure that you have the best tools for analysing the data,’ he said.

‘We also put in quite a number of proposals ourselves. I am leading one, and I am a co-investigator on others totalling 200 hours of time. We will also be taking part in what is called the ‘Early Release Science’ observations – a community effort which ought to see the first data in early 2022.’

As well as being outside the atmosphere, like Hubble, one of the big advantages of the new James Webb Telescope is that its instruments are customised for detecting the light from the early universe. James Webb will orbit 1.5 million km from the Earth to avoid its heat and light and will be kept cold using a massive sunshield. This is because it has been designed to detect infrared light, which is the part of the electromagnetic spectrum that lies beyond red light. Galaxies and stars from the very early universe are only visible in infrared as their light has been ‘red-shifted’, a phenomenon caused by the huge speeds at which they are travelling away from us.

Professor Glazebrook’s Laureate team is currently in preparation for the work that is to come analysing the data from James Webb, which will arrive as a flood of data that needs to be processed by sophisticated, custom designed software.

‘The new development in the field is ‘deep learning’ – this is where you train a computer to recognise the kinds of objects that you are looking for. A couple of years ago we started experimenting with deep learning, using images directly, and with this we were able to compile a huge catalogue of gravitationally-lensed galaxies much faster than a human could do it.’

Professor Glazebrook’s students are also busily preparing to use telescope time: post-doctoral researchers, Dr Themiya Nanayakkara, who is developing spectroscopic modelling codes to determine galaxy evolution, and Dr Colin Jacobs, developing machine learning techniques. Two PhD students, Monserrat Martinez-Marín and Shingo Tanigawa, are also assisting in the measurement of red-shifts.

The Australian Laureate Fellowship will eventually support 4 post-doctoral scientists and 4 PhDs, but Professor Glazebrook says he’s ‘keeping his powder dry’ till the telescope is in operation, following a launch currently scheduled for 21 October this year.

‘It is about to be packed up on the boat to go to the launch site in French Guiana. There shouldn’t be further delays because there will be no more tests. Of course, we are all worried about the mirror unfolding. And there is apparently a genuine risk of attack by pirates, who are still active in South America even today, which is why NASA is keeping the shipping date secret. But a more common concern is that the automatic unfurling of the telescope in space will somehow not go according to plan, leaving the astronomy community in limbo.’

‘My emotions are all mixed up on this. Hubble was launched when I had just finished my PhD and I was all set to begin work on its data. Then there was a problem with the mirror which had to be corrected with a fix-it mission. So I spent about two years preparing for it to be fixed, but this gave me time to write the programs that many of us would use to process the data.’

‘When Hubble finally was working, the images were unlike anything we had seen before, astronomy was changed forever. James Webb will be like that.’


Image: Professor Glazebrook his Laureate and Astro3D postdocs and students.

Top row: James Esdaile (PhD), Tyler Hughes (PhD), Aaron Myszka (PhD), Monserrat Martinez (PhD), Colin Jacobs (PDRS)

Front row: Shingo Tanigawa (PhD), Dorota Bayer (PDRA), me, Juan Espejo (PhD), Themiya Nanayakkara (PDRA)

Photo credit: Christian Lehmann