The James Webb Space Telescope
Artist's concept of the James Webb Telescope in space. Credit: NASA

The James Webb Space Telescope

14/10/2021Written by Eleanor Morton

After 25 years, the James Webb Space Telescope is set to launch in December 2021. We look back on the satellite’s journey.

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mascot Telescope Right
The fully assembled Webb Telescope with its sunshield that will fold up around the telescope for launch. Credit: NASA

In 1996 NASA proposed their newest satellite, named the Next Generation Space Telescope, with the aim to produce a telescope better than Hubble without the expensive price tag that usually comes with space telescopes.

By 2002 the project had been renamed the James Webb Space Telescope (JWST), after NASA’s second administrator, and was scheduled to launch in 2010. Problems with budget and funding caused the launch date to be pushed back and back, and after a long 25 years, the JWST is now due to lift-off in December 2021 and take its first look into our universe.

In the Footsteps of Hubble

In the Footsteps of Hubble
The Veil Nebula. Credit: ESA/NASA Hubble
In the Footsteps of Hubble
Hubble telescope photographed above Earth during STS-125 shuttle mission. Credit: NASA-SDO.

With its 6.5 meter primary mirror, the James Webb Space Telescope will be able to see further into the universe than ever before, following in the footsteps of its cousin the Hubble Space Telescope. Hubble and JWST were both designed and developed by the Space Telescope Science Institute to help fulfil their aim of aiding humanities exploration of the universe.

Launched in 1990 by the space shuttle Discovery, the Hubble Space Telescope has helped opened our eyes to the wonders of our universe, aiding in numerous discoveries over the past 30 years. Including the discovery of dark energy, which changed the way we look at our universe and how we move within it, and providing evidence that in the centre of every galaxy is a supermassive black hole.

Perhaps the most famous aspect of Hubble are its breathtaking images showcasing previously unseen corners of our galaxy and beyond. Whilst Hubble looked out in the Optical and Ultraviolet (UV) wavelengths, the JWST will be looking beyond at the longer wavelengths of Infra-red enabling it to look back even further to the origins of our universe and delve deeper into Hubble’s discoveries.

Mission Overview

Mission Overview
Comparison of the Carina Nebula in visible light (left) and infrared (right). Credit: ESA/NASA Hubble
Mission Overview
James Webb Space Telescope wavelength range, mirror size, and location specs. Credit: NASA

One aspect of the James Webb Space Telescope that sets it aside from most other space telescopes is its position. Whilst most telescopes are found in low Earth orbit (LEO), less than 1000 km from the Earth’s surface, the JWST will be around 1.5 million kilometres away on the other side of the Moon at what is referred to as the second Lagrange point. Although this makes it harder and more expensive to launch due to its distance from the Earth, for astronomers it’s ideal as the satellite is removed from the normally interfering infra-red radiation given off by Earth. This radiation and visible light can make observing the universe in LEO more difficult and has been described as like trying to take a picture of the stars in broad daylight.

Alongside its position, JWST’s mirrors are another aspect that makes this telescope different to the ones before. In fact, JWST’s mirror is the largest space mirror thus far comprising of 18 segments covering 6.5 metres at its widest point. The mirror will act like a bucket, catching a large array of light from the universe and, along with seeing in infra-red, will allow us to see further back into space than ever before to the formation of some of the universe’s earliest galaxies.

Take a look at the image showing the Monkey Head Nebula. Previously, when looking at visible light wavelengths, we could see beautiful images but not many stars. When we look using infra-red wavelengths, like JWST, we can see through the dust clouds and reveal countless new stars and galaxies we may never have spotted before.

10 Key Facts

1. The Webb Telescope will be the largest, most powerful and complex space telescope ever built and launched into space.

2. A total of 14 countries worked to build the James Webb Space Telescope.

3. The telescope will be launched on an Ariane 5 rocket which also launched BepiColombo and the Galileo satellites.

4. Webb’s primary mirror is 6.5m at its widest point and is made up of 18 segments.

5. Webb’s sunshield, which helps keep the telescope cool, is the size of a tennis court.

6. It will take Webb 30 days to get to its point of orbit compared to 3 days for it to reach the Moon.

7. Webb is 100 times more sensitive than the Hubble Space Telescope.

8. Webb will be able to see right through and into massive clouds of dust, where stars and planetary systems are being born.

9. Webb will orbit the Sun, a million miles away from Earth, four times further away than the Moon!

10. It will peer back in time over 13.5 billion years to see the first galaxies born after the Big Bang.

The Long Road to Lift-off

The Long Road to Lift-off
Image Credit: ESA

The James Webb Space Telescope has come a long way in the last 25 years. From 1996 to 2021, the production of JWST has allowed scientists to develop some of the best space technology on the planet but the telescope is a long way from its original launch date of 2010.

Throughout the journey of JWST there have been numerous setbacks resulting in its launch date being pushed back not once but 10 times due to budget constraints and scheduling issues. Where once the telescope’s budget sat at a reasonable $500 million that figure has now grown to $9.7 billion, at time of launch, making it NASA’s most expensive space telescope to date.

It was always going to be expensive, with a mission plan that grew from a simple high performance, low-cost satellite to a telescope capable of showing us the early stages of the Universe. Although JWST only has a lifetime of 10 years, it aims to give us insights into the 13.5 billion year history of our universe with its ability to look at many different aspects of space and solve many mysteries along the way.



Although the wait has been long, the James Webb Space Telescope promises to be worth it. With the hope of unprecedented discoveries just around the corner that will build on the knowledge of Hubble and others that have gone before it. We wish it good luck and safe travels as it begins this new chapter of space exploration.


About the author: Eleanor Morton graduated from the University of Leicester with a Masters in Physics. She is an aspiring science writer and can be found on Twitter @ElMortonSci.