James Webb Space Telescope- Everything you need to know

James Webb Space Telescope- Everything you need to know

A huge infrared space telescope has long been a dream of scientists. The Shuttle Infrared Telescope Facility (SIRTF) was planned in the United States while the Space Shuttle was being developed, and the potential for infrared astronomy was recognised at the time. In comparison to terrestrial telescopes, space observatories were free of infrared light absorption by the atmosphere. Astronomers now have access to a “whole new sky” thanks to space observatories.

Infrared telescopes, on the other hand, have a drawback: they must be extremely cold, and the longer the wavelength of infrared, the colder they must be. If not, the device’s background heat overwhelms the detectors, effectively blinding it. This can be avoided through careful spacecraft construction, namely by encasing the telescope in a dewar filled with an exceedingly cold substance like liquid helium. As a result, the lifespan of most infrared telescopes is limited by their coolant, which might be as short as a few months or as long as a few years.

In some circumstances, such as the Spitzer Space Telescope’s extended missions and the Wide-field Infrared Survey Explorer’s extended missions, it has been possible to maintain a temperature low enough through the architecture of the spacecraft to perform near-infrared studies without a source of coolant. 

Another example is Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) sensor, which began with a block of nitrogen ice that depleted after a few years but was later upgraded to a cryocooler that worked indefinitely. The James Webb Space Telescope uses a combination of sun shields and radiators to keep itself cool, with an extra cryocooler for the mid-infrared equipment.

What goes behind the JWST?

NASA, the European Space Agency (ESA), and the Canadian Space Agency are working together to create the James Webb Space Telescope (JWST) (CSA). It will take the place of NASA’s Flagship astrophysics mission, the Hubble Space Telescope. 

The JWST, which will be launched on Ariane flight VA256 on December 22, 2021, will provide improved infrared resolution and sensitivity over Hubble, allowing for a wide range of astronomical and cosmological investigations, including observing some of the universe’s most distant events and objects, such as the formation of the first galaxies, and detailed atmospheric characterization of potentially habitable exoplanets.

The Optical Telescope Element, the JWST’s primary mirror, is made up of 18 hexagonal mirror segments made of gold-plated beryllium that combine to form a 6.5 m (21 ft) diameter mirror, much larger than Hubble’s 2.4 m (7 ft 10 in) mirror.

Unlike the Hubble telescope, which observes in the near ultraviolet, visible, and near infrared (0.1 to 1 m) spectra, the JWST will observe in a lower frequency range, ranging from long-wavelength visible light to mid-infrared (0.6 to 28.3 m), allowing it to observe high redshift objects that are too old and distant for Hubble to observe. 

To observe infrared without interference, the telescope will be placed in orbit near the Sun–Earth L2 Lagrange point, and a massive sunshield composed of silicon- and aluminum-coated Kapton will keep the telescope’s mirror and instruments below 50 K (223 Β°C; 370 Β°F). 

The development work is being led by NASA’s Goddard Space Flight Center, and Webb will be operated by the Space Telescope Science Institute following launch.

Northrop Grumman is the principal contractor.

It is named for NASA Administrator James E. Webb, who served from 1961 to 1968 and was a key figure in the Apollo programme. The project began in 1996 with an initial launch date of 2007 and a budget of US$500 million, however there were multiple delays and cost overruns, and the programme was redesigned in 2005. 

The JWST’s construction was finished in late 2016, and the testing phase began shortly after. The launch was postponed again in March 2018 because the telescope’s sunshield ripped during a rehearsal deployment. Following suggestions from an independent review board, the launch was again postponed in June 2018. 

Due to the COVID-19 pandemic, work on the telescope’s integration and testing was put on hold in March 2020, causing more delays. The launch date was pushed back to October 31, 2021, when work was resumed. Due to issues with the Ariane 5 launch vehicle, the launch date was pushed back until December 22, 2021.