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James Webb Space Telescope Facts – The Biggest Optical and Infrared Astronomical Observatory

James Webb Space Telescope Facts - The Biggest Optical and Infrared Astronomical Observatory

What is James Webb Space Telescope

The James Webb also called (JWST or Webb) is a space telescope considered as the biggest optical and infrared astronomical observatory ever placed in orbit. It is planned to succeed the Hubble Space Telescope and it is also expected that it will have an impact on astrophysics missions by NASA. The name James Webb originated from NASA’s administrator (1961 to 1968) named James E Webb who performed an essential role in the Apollo Program.

Expected Discoveries of James Webb Space Telescope:

  • The main mission of ‘JWST’ will be the search for galaxies formed ever before and luminous objects formed after the Big Bang.
  • It will determine how galaxies revolve around the sun from the day of formation until now.
  • It will be able to see into the huge clouds of dust in space which are hazy to visible light. 

Manufacturing Companies:

  • JWST is manufactured by Northrop Grumman and Ball Aerospace and Technologies. There is also a specific contribution of the European Space Agency and the Canadian Space Agency. 
  • Trials for the launch took place at Redondo Beach in California where its final testing was completed in collaboration with NASA.

What is it composed of?

  • JWST is made up of beryllium which is a strong but lightweight material and can stand through really cold temperatures.
  • JWST has to be kept at -375(Fahrenheit) for its instruments to function properly.

Constructional Specification of James Webb:

  • JWST will appear 100,000 times fainter than the star which is faintest to be seen with a naked eye from Earth.
  • It will be four times away from the moon and 940,000 miles away from Earth.
  • It is as wide as a tennis court with the height of a three-story house. 
  • The biggest element of the telescope is its sunshield, it is composed of 5 very thin layers made of Kapton polyimide that protects the mirror from sunlight and cools the telescope after sensitive matters to -220C|-364F.

Difference between Hubble & James Webb:

  • James will orbit around the Sun, unlike Hubble that revolves around the Earth. 
  • Lightweight optics, Deployable sunshield, Foldable segmented mirror, Improved detectors, Micro shutters, Cryogenic actuators, mirror controllers are the major innovations of James Webb over the Hubble Space Telescope.

    james webb vs hubble
    Primary mirror size comparison of Hubble and James Webb space telescopes.

Instruments Used In James Webb:

  • The Near Infrared Camera (NIRCam) is the main set of the eyes of the telescope, with this cam we will be able to see all the stars in the universe and the planets around them.
  • The Near Infrared Spectrograph (NIRSpec) will collect the chemical and physical properties of an object.
  • The Mid Infrared (MIRI) instrument is for mid to long infrared wavelength ranging from 5 to 27, which will allow you to see how stars have been born, many unknown objects of the Kuiper Belt as an astronomer hope will help to find the 9th mysterious planet. 
  • The Fine Guidance Sensors (FGS) will help accurately pointing out high-quality images.
  • The Near Infrared imager & Slitless spectrograph (NIRISS) will help in finding exoplanets and the first light of distant objects.
  • As a shaky camera makes blurry photos so as vibrators installed in ‘JWST’ can make the image quality low, to make a good image quality JWST has installed the rubber shock absorb cushions.
  • Another important element of the telescope is the central computer which controls the operations of the observatory while orbiting.

Launch Date of James Webb:

  • NASA informed that the telescope will be launched in October 2021. 

How James Webb will be sent to Space?

  • Since there is no such wide rocket that can hold the telescope, a folded sunshield and mirror will be launched and will be unfolded when it reaches its destination.
  • To fit on the rocket with its weight limit it is necessary to perform its observations, it was designed to be lightweight and it also has a flexible structure.
  • The flexibility of JWST makes it susceptible to vibrations whenever it moves. 

The vehicle for Launch:

  • The vehicle that will be used for launching JWST is Ariane 5 which is part of the European contribution.
  • Ariane 5 is considered the most reliable launch vehicle and capable of delivering the JWST to its destination point.

Here comes the Fun Fact:

  • The fun fact is that the JWST will be a powerful time machine because it will be able to capture the light that’s been traveling in space for as long as 13.5 billion years even from the time when the first galaxies and stars were formed out of the darkness of the early universe.

Important measurements concerning James Webb:

Launch Date October 2021
Duration Of Launch 5 to 10 YEARS
Launch Vehicle Ariane 5 ECA
Total Mass 6200kg
Diameter Of Primary Mirror ~6.5 m (21.3ft)
Clearance of Aperture Of Primary Mirror 25m²
Material Of Primary Mirror Beryllium coated with Gold 
Mass Of Single Primary Mirror Segment20.1kg for a single beryllium mirror
Mass Of Entire Primary Mirror Segment Assembly (PMAS)39.48kg 
Total Mass Of Primary Mirror 705kg
Number of Primary Mirror Segment 18
Focal Length 131.4meters
Optical Resolution ~0.1 arc-seconds
Coverage Of Wavelength 0.6-28.5 microns
Size Of Sun Shield 21.197m x14.162m (69.5ft x 46.5 ft)
Sun Shield Layer 5 Layers
Temp Of Sunshield LayersLayer:1

Max temp 383K = approx 231F


Max temp 221K= approx -80F

Min temp 36K=approx -394F

Orbit1.5 million km from Earth orbits at the L2 point 
Operating Temp Under 50K (-370F)
Gold Coating Measurements Thickness: 1000 angstroms 

Surface area: 25m²

The coating is calculated to use 48.25g of gold


Cost Of JWST10 Billion USD 


  • How will JWST transmit its data to Earth?
    James will transmit its science and engineering data through a high-frequency radio transmitter. NASA Deep Space Network does have big radio antennas which will receive the signals and forward them to the Operation Center of Space Telescope Science Institute which is placed in Baltimore, Maryland (USA).


  • What makes it so special than other Telescopes made to the date?
    One of the major things that James has, the distortion canceller which makes the telescope more smooth for sending accurate data to the scientists.

  • Why is it much better than the Hubble Space Telescope?
    It has to be better than Hubble because it has a larger field of view which will significantly cover an area more than ~15 times of NICMOS Cam inserted on Hubble could.


  • Is James more powerful than Hubble?
    Of course, it is 100 times more powerful than Hubble, it is bigger in size, and not just that, it will even be able to peer back into the time than the Hubble could. 


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