NASA’s James Webb telescope being tested for space
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Nearly 25 years in the making, the impressive bit of kit is fuelled and ready to launch from the European Spaceport in French Guiana later this month. The James Webb Space Telescope (JWST) is the single biggest instrument NASA has ever built and with that come expectations about its ability to explore the youngest and farthest corners of the universe. The pressure to perform is all the more palpable as the £7.5billion ($10billion) construction boasts more than 300 points of failure that threaten to scupper what NASA has called “the most complex sequence of deployments ever attempted in a single space mission”.
Due to its sheer size – about as big as a tennis court when unfurled – the telescope will launch aboard an Ariane 5 rocket on December 22 folded like the world’s most expensive origami project.
Unsurprisingly, Dr Megan Argo, an astrophysicist at the University of Central Lancashire, told Express.co.uk that scientists around the globe are feeling a certain amount of trepidation in the days before launch.
But there is also a great deal of excitement about the mission and the astronomical breakthroughs many believe the JWST will make.
The telescope has been widely touted as this generation’s successor to the iconic Hubble Space Telescope, which launched in April 1990.
Hubble provided scientists with striking images of some of the most distant and fascinating objects in the universe and has revealed the cosmos in never-seen-before detail.
The JWST will give scientists a “different window” onto the universe, and the results are going to be out of this world, according to Dr Argo.
She said: “In many ways, it is a successor to Hubble and Hubble isn’t expected to last much longer as it’s well past the original operational design lifetime anyway.
“So it is the next big space observatory and it is working in a different part of the spectrum; it is looking at the infrared, so the kind of images we’ll get from James Webb are different from the ones we’ve had from the Hubble Space Telescope.
“It will give us a different window on the universe but it’s still going to give us spectacular pictures of galaxies, and star systems and star formation.
“And the spectroscopy that it will do will be quite exciting as well.”
The key difference between the two is that JWST will look at the universe in infrared wavelengths of light.
This will allow the telescope to peer through nebulae of gas and dust that are otherwise impenetrable to visible light.
But it will also allow scientists to detect some of the oldest objects in the universe, whose light has shifted to the red end of the electromagnetic spectrum.
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Dr Argo said: “Hubble has allowed us to look a long way and has allowed us to study galaxy evolution in a lot of detail, but it can’t see quite far enough to observe the very first stars and galaxies.
“JWST wins in two ways over Hubble in this regard: it’s larger, and so is more sensitive and can see fainter things, and it’s using infrared rather than optical light.”
It is estimated the JWST will detect the light from objects some 13.5 billion light-years away – light that has travelled towards the Earth for 13.5 billion years.
In other words, the telescope will observe the universe just as it was within 300 million years of its birth.
Due to the ongoing expansion of the universe, the light from these early days of the universe has been stretched out and shifted in colour towards the red end of the spectrum.
Dr Argo said: “Everyone has probably experienced the way sound from an ambulance gets lower in pitch as it moves away from you; the light from the distant universe is shifted in a similar way because of the expansion of the universe.
“Light from the earliest objects is ‘shifted’ towards redder colours, making those first stars appear brighter – and hence much easier to see – with an infrared telescope than with an optical telescope.
“If we want to see those first stars and galaxies, a large infrared telescope is the best way to do it.”
English poet John Donne once said “no man is an island” and the same can be said of NASA’s various space telescopes.
Although the JWST promises to deliver some groundbreaking science, its work will be complemented by a wide array of other instruments tuned to see the universe in other wavelengths of the electromagnetic spectrum.
The Hubble telescope was built to primarily make observations in visible light, as well as some infrared and ultraviolet radiation.
NASA’s recently launched Imaging X-Ray Polarimetry Explorer (IXPE) spacecraft, meanwhile, will study the polarisation of X-ray radiation streaming from black holes, dead stars and more.
Other instruments like the Swift Gamma Ray Burst Explorer and the Fermi Gamma-ray Space Telescope focus on gamma radiation from distant bodies, while the Wilkinson Microwave Anisotropy Probe observed microwave radiation.
Altogether, the dozens of missions launched by NASA and its international partners across the globe collect large quantities of data that have shaped our understanding of how the universe came to be the way it is today.
The only thing now, Dr Argo said, is to wait for launch day with both toes and fingers crossed.
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