Fun Facts about the James Webb Space Telescope (JWST)

James Webb Space Telescope (JWST) will be a successor to Hubble Space Telescope. JWST is a large, infrared-optimized space telescope. The project is working to a 2018 launch date. Its instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range and will have the largest mirror ever placed in space. Webb Telescope will be the premier space observatory for astronomers worldwide, extending discoveries of the Hubble Space Telescope.

JWST is an international collaboration among NASA, ESA (European Space Agency), and Canadian Space Agency (CSA). JWST will launch in 2018 from French Guiana on an Ariane 5 rocket. Webb Telescope will focus on four key science themes that seek to unravel the mystery of how the universe grew from a big bang into galaxies, stars, and planets

o   First Galaxies

o   Galaxy Assembly

o   Birthplace of Stars

o   Planets and life

Webb Telescope will be both the largest and coldest structure cooled using passive (i.e., no power required) radiative thermal cooling. The five layer sunshield, the size of a tennis court, will protect the telescope from light and heat from the Sun, Earth, and the Moon. It will be an Infrared telescope, which means it will detect electromagnetic radiation with longer wavelengths than those of visible light. Infrared radiation is also known as “heat radiation”, so the telescope needs to be kept at a super cool temperature. The five layer sunshield, the size of a tennis court, will protect the telescope from light and heat from the Sun, Earth, and the Moon.

Webb Telescope will travel to the second Lagrange point (L2) approximately 1 million miles away from Earth.  The opposite side of the Earth from the Sun (nearly 4x’s the distance between the Earth to the Moon). The L2 point lies outside the Earth’s orbit while it is going around the Sun. The combined gravitational forces of the Sun and the Earth can almost hold a spacecraft (Webb Telescope) at this point, and it takes relatively little rocket fuel to keep the spacecraft near L2. During the roughly 3 month trip to L2, the Webb deployments will occur, and roughly 6 months after launch, scientific operations will begin. Webb Telescope will view stars, galaxies, planets in infrared light spectrum. The cold and stable temperature environment of theL2 point will allow Webb to make the very sensitive infrared observations needed. The mirror and instruments operate at a temperature less than 50K, roughly -370 degrees Fahrenheit or -223 degrees Celsius.


·        Webb’s mirrors are made of beryllium (18 mirror segments to work as one mirror)

o   Webb Telescope will be the first to use a deployable segmented mirror

o   Webb Telescope mirror is 21 feet across and 7 Hubble Space Telescope mirrors would fit into Webb’s mirror.  Which means Webb has 7x more light collecting than Hubble

o   Beryllium is used for the mirrors because it is 6x’s stiffer than steel but lighter (less dense) about 1/3 the weight of aluminum

o   Beryllium is mixed with metals and used in cars, computer, and cell phones.  Only pure beryllium is used in x-ray machine, space satellites, and now Webb Telescope

Nobel Prize winner in Physics – John Mather, Webb’s Project Scientist, won the Nobel Prize for proving the Big Bang Theory of the Universe with his work on Cosmic Background Explorer Satellite (COBE)

Fun Facts about JWST!

·        Webb Telescope is larger than the rocket it is launching on – 3 stories high and size of a tennis court!  The only way the telescope can fit into the rocket is to be folded up like an origami and once into space will unfold like a transformer.

·        The sunshield is made of Kapton.  Material that is similar to Mylar balloon!

·        The sunshield protects telescope from the Sun, Earth, and Moon’s light and heat. It’s like wearing sun protection of SPF 1,000,000 (1 million)!

·        One sunshield has 10,000 seams – cannot get one piece of material the size of tennis court.  Kapton comes in “bolts” of material (like you see in Fabric stores!)

·        Imaging from Webb is so good it will see details the size of a penny at a distance of about 24 miles away or a foot ball at a distance of 340 miles!

·        When you take a picture with a digital camera, you must have steady hand or picture will come out blurred.

o   Webb telescope is so steady in its pointing ability that using the same penny from 24 miles away would be like keeping a laser pointer on the center of the penny.

·        How well can Webb see? 

o   If Webb telescope was on the surface of the Earth looking at the moon and a candle was lit on the shaded side of the moon, the telescope would see it!

o   Objects which Webb Telescope will observe would appear to our eyes as faint as a dim night light shinning from the surface of the moon

o   Webb’s seeing ability is 1,000 times better than the human eye!

o   Webb telescope will be able to see the heat from a bumble bee from the moon!


If you can’t imagine how huge James Webb Space Telescope is, then look at the picture and try to find me in front of the model of JWST!

(Clue from the Editiors, Prosit & Shubhasis : Look for the ‘Madhyo-Moni’!)

About the Author

Ratnabali (Day) Sengupta

Principal Engineer

NASA Goddard Space Flight Center

Washington D.C. Metro Area







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  1. Prosit Mukherjee says:

    You mean to say that with this beast my wife will be able to keep an eye on me all the time even at Moon? Mann, that’s Deadly!

    Jokes apart, Bui thanks a lot for this little gem. We will be looking forward to the series, the next one should be on Hubble as you promised earlier.
    BTW, I couldnt help giving the hint where you are in the pic. Really looking smart!

  2. sumana saha says:

    Very well written Bui, and really enjoyed the fun facts, especially the information that such a huge thing can be folded like an origami to fit in the rocket on which it launches!! Don’t mind Boltu…boys will never grow up and will forever be terrified of their lovely wives:). Post many more like this.

  3. Subho SARKAR says:

    Hi Buiya ,
    We all are really grateful for sharing such an extraordinary & yet another mind boggling creation from the researchers up their.
    Its quite an amazing feat of the entire planning and process of the James Webb Space Telescope (JWST). It seems to be much revolutionary aspect than its predecessor the great Hubble Telescope .
    Thank you .

  4. Shubhashis says:

    Its great to feel an ex-student of Visva Bharati, incidentally my class mate as well in Physics Deptt, Siksha Bhavana, is a part of the team (the ‘madhyamoni’ in the snap-front row). It is easy to comprehend the complexity of launching such a huge mirror to reflect all relevant rays to the focus point of data collection; the materials and technology used can be a huge area of interest for hard core scientific community. It is also great to feel that in spite of so much politics involving different countries mankind has remained steadfast on scientific exploration which will essentially build the future of the human race.

    I am just back from another incredible spectacle on Earth, called the Maha Kumbha Mela (the one in each twelve year) at Prayag, Allahabad, which had an estimated congregation of 4 Crore people on 10th February- the Mouni Amabasya Day; absolutely stunned by the the human sea (or shall I say ocean!) on the Kumbh Mela Ground. I have heard that a team of observers from Havard University has come to Prayag, Allahabad simply to observe how such crowd is essentially managed! A religious gathering of this size is an stupendous event to experience.

    But it is great to find that the scientific pursuit has kept the human intellect focused to the unknown future. To be honest, I still believe, in spite of so much pessimism and conflict over GM Crops and things like those; it is essentially science only which can deliver us the solutions if we can handle the knowledge properly. After all Science is the only Religion whose language remains uniform for the whole mankind!

    Thanks Ratnabali; and truly excited over the possibility of more information reaching us from you about the ‘Star World’.

  5. Boisali Biswas says:

    Very inspiring, makes us really proud, specially because so many common people randomly comment on how students from VB are only good at art, dancing and singing, etc. and have nothing to do with the hard sciences! This really proves that they are all over the world, in all areas 🙂 Shabash!

  6. Shubhashis Mitra says:

    Bipasha Chatterjee
    This is a very interesting post. Thank you to Ratnabali/Buiyadi. We are really proud of her contribution to the telescope projects at NASA.

    Ravi Dwivedi
    Great Buiya…keep on going!!!

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