NASA’s James Webb Space Telescope Offers Glimpse Back in Time

Following the success of the renowned Hubble Space Telescope launched in 1990, NASA’s Great Observatories engineered its most powerful instrument, the James Webb Space Telescope (JWST), to probe the deepest stretches of the universe.

The $10-billion instrument was launched into space on 15 December 2021 and, just over six months later, returned its first spectacular images.

The telescope captures faint infrared light, using a 6.5 metre wide gold coated mirror made up of 18 segments, which is reflected into cutting-edge scientific instruments to produce full colour, high resolution images of the cosmos.

So how does it work?

The light emitted by distant stars takes billions of years to travel across space before eventually reaching the JWST.

Since the Big Bang, the universe has been expanding and accelerating causing these early light particles to stretch into longer (infrared) wavelengths which are not visible to the human eye. A key improvement between the Hubble and JWST is the JWST’s ability to observe in both near and mid-infrared wavelengths, compared to just near infrared. The Mid-Infrared Instrument (MIRI) aboard the JWST was designed by an international consortium from 10 countries, led by British scientists.

By having the ability to analyse ‘more-stretched’ mid-infrared light, scientists can see further back in time and understand what happened during the formation of the universe, up to around 13.5 billion years ago, and potentially unravel some of the mysteries around the Big Bang event, approximately 13.8 billion years ago.

Another advantage of analysing infrared light, rather than visible light, is that it can pass through cosmic dust; regions of space that cultivate early star formation.

During its 30-year lifetime, the Hubble telescope aided huge scientific discoveries, including the observation which affirmed the existence of supermassive black holes and the accelerating expansion of the universe due to “dark energy”.

At the beginning of its 20 year-tenure, it is impossible to predict what the JWST will discover at such high resolution. The telescope has already captured an image of the oldest galaxy we have ever seen in the universe, dating back to 300 million years after the Big Bag – reinforcing scientists’ belief that the JWST’s observations have the potential to question our current understanding of the universe.