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Explainer: The history and mission of James Webb

Explainer: The history and mission of James Webb

The first full-colour images from the James Webb Space Telescope made global headlines this week as they revealed the universe in unprecedented detail. But what is James Webb, and how will it change how we understand space? Here, Liam McAneny explains everything you need to know. 

What is the James Webb Space Telescope?

The James Webb Space Telescope has often been described as the “spiritual successor” to Hubble. It is the largest and most powerful space telescope ever to be built. It is an infrared light telescope that will detect light beyond the visible spectrum. This is an important distinction from the Hubble, which operated mainly in the visible spectrum.

With the JWST being an infrared telescope, two main challenges arose. Infrared telescopes need a large mirror to collect enough light to make observations. They also need to be kept extremely cold, so no stray infrared light sources interfere with the light being observed. As a result, the JWST was created with a vast segmented mirror with a diameter of 6.5 metres and a sun shield about the size of a tennis court to protect the mirror and telescope array from the sun’s heat.


James Webb is also equipped with four separate cameras to capture different aspects of imagery. The primary and most important of these cameras is the Near Infrared Camera (NIRCam). This camera plays a vital role in aligning the telescope mirror. It is supplemented by the Mid-Infrared Instrument (MIRI) camera, the Near-Infrared Spectrograph (NIRSPec) and the Fine Guidance Sensor/Near-Infrared Imager and Slitless Spectrograph (FGS/NRiss).

History of its development

The James Webb Space Telescope was developed at its most basic conceptual level in 1989, even before the launch of Hubble. In September 1989, NASA hosted the first Next Generation Space Telescope Workshop, which proposed the idea of a passively cooled, near-infrared telescope in high-Earth orbit. In 1996, a committee formally recommended that NASA develop an infrared space telescope, a mirror with a diameter of over 4 metres and would orbit far beyond the moon. Further studies on refining the technical requirements for the telescope were conducted throughout 1997. 

By 2002, NASA had put together several teams to build the instruments necessary for the telescope and selected a group of astronomers to oversee the construction process. It was also when the instrument was formally named James Webb.


While the JWST was originally planned solely by NASA, the European Space Agency and the Canadian Space Agency joined in developing the project in 2004 and 2007, respectively. Construction began on the telescope in 2004 at NASA’s Goddard Space Flight Center in Maryland. 

The construction contract was awarded to US aerospace engineering company Northrop Grumman Aerospace Systems.

A litany of delays

The complexity of the scientific and technical challenges that faced the JWST resulted in several delays and budget re-adjustments. Originally, the JWST was scheduled to launch in 2011. Early during its construction, it became clear that the JWST would require more time in development and a significantly higher budget.

In 2005, a project replanning was completed, with an estimated launch date of 2013 and a budget of $4.5 billion for its entire life cycle. In 2010, another mission review moved the launch date tenuously to 2015, acknowledging it could be as latest as 2018.

Further delays were caused by system failures within the JWST’s sun shield during a practice deployment in 2018. This resulted in a further delay of nearly three years until March 2021. More engineering problems plagued the telescope through this time, with the telescope finally arriving at its launch destination of French Guiana on 12 October 2021.

Finally, a launch date

Following the years of delays, a launch date was set for 25 December 2021, aboard one of the European Space Agency’s Ariane 5 rockets. 

Despite the construction completed, the launch vessel chosen and the launch date set, there were still many potentially mission-ending errors that the JWST had to face before it was successfully launched, positioned and ready to observe the universe.

A 2018 review identified 344 potential “single-point” failures. This term describes a failure for which there was no redundancy and would cripple the entire mission if it failed. Despite these severe challenges facing the project, the JWST launched successfully on Christmas day and began its months-long journey to its final observation position.

Travelling to Lagrange Point 2 and setting up

Once its launch was completed, the JWST had to make a 29-day journey to Lagrange Point 2.

During this period, the JWST broke from the faring that protects its telescope and then began to deploy the countless instruments and mechanisms necessary for its proper function.

The most critical of these was the deployment of the sun shield frame that protects the telescope from the sun’s heat and the unfolding of the 18 mirror segments into its final telescopic mirror.

The initial unfolding of the mirror took 10 days alone, with the subsequent process of fine-tuning the mirrors using 126 exceptionally precise actuators attached to the backside of each mirror taking months.

Once the mirrors were calibrated, the JWST began test imaging and target sighting using its NIRCam to select observation points. 

What’s in the future for James Webb?

Following its first set of five images, released on 12 July by NASA, the JWST is set to get straight to work on its primary mission, which NASA says is “Science!”

A broad range of international research teams has submitted proposals for using the JWST. In total, there were 286 successful proposals to NASA for using the JWST and its data. JWST will have around 6,000 observing hours available during its first cycle of operation, which will take about a year.

Barring no critical incidents or failures, the JWST mission is expected to run for at least 10 years. Thanks to a near-perfect launch, the JWST was able to conserve a significant amount of fuel and may be able to operate in orbit for “significantly more than a 10-year science lifetime”. 

Adam Thorn

Adam Thorn

Adam is a journalist who has worked for more than 40 prestigious media brands in the UK and Australia. Since 2005, his varied career has included stints as a reporter, copy editor, feature writer and editor for publications as diverse as Fleet Street newspaper The Sunday Times, fashion bible Jones, media and marketing website Mumbrella as well as lifestyle magazines such as GQ, Woman’s Weekly, Men’s Health and Loaded. He joined Momentum Media in early 2020 and currently writes for Australian Aviation and World of Aviation.

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