The most powerful space telescope, the James Webb Space Telescope (JWST), is set for launch on December 25 aboard an Ariane 5 rocket in French Guiana. Find out what it takes to become a telescope that changes our way of seeing the Universe in this article.
What is the Destination of the JWST?
Unlike the Hubble Space Telescope, the JWST will conduct observations at the L2 Langrange point. At that point, the object’s orbital speed should have been slower than that of Earth, but the object is gravitationally influenced just enough that it orbits in sync with the Earth. Keep in mind that this Langrange point, along with the L1 and L3 Langrange points, are unstable, and the spacecraft located there, including JWST, need to actively fire thrusters to keep them in sync with our planet.
Why don’t mission engineers choose to just put it on low Earth orbit (LEO), just like the Hubble Space Telescope? This is because the telescope wants to detect even the faintest signals from outer space, and it just doesn’t want interference from relatively bright objects, including the Sun, Earth, and Moon. Moreover, the telescope’s science instruments should be kept cool, so it’s unacceptable for the main instruments to face the Sun.
What is the Structure of the Telescope?
The James Webb Telescope is so powerful due to its enormous mirror. Remember that the larger the mirror, the more light can a reflective telescope absorb so that smaller details can be resolved. The diameter of the mirror of the JWST will be 6.5 meters, compared to that of the Hubble Space Telescope, which is 2.4 meters wide. Moreover, the mirror will be coated with gold for it to reflect infrared light more efficiently.
Because the JWST is an infrared telescope, it has to cool its instruments down effectively in order for it to make meaningful observations. It uses a large sunshield that blocks the supply of light and heat to the instruments so that it can cool down to just 40 degrees above absolute zero (about -233oC).
The Deployment of JWST
As the telescope with the enormous mirror and sunshield must be launched in a crammed space within the fairings of the launch vehicle, it must deploy its components cautiously. Firstly, the sunshield pallets will deploy 3 days after launch. One day later, the spacecraft tower, which contains the science instruments and mirror, gets extended. 6 to 7 days after launch, the sunshield, which is responsible for cooling, will deploy. A few days after that, the primary mirror will also expose its edges, completing the deployment process.
Why is JWST an Infrared Telescope?
Keep in mind that JWST will be doing observations in the infrared spectrum. Why is that? It’s because of the Doppler effect. When an object is moving farther from us, its wavelength will lengthen as the effect of redshift. Likewise, if it is getting close to us, its wavelength will become shorter as the effect of blueshift.
JWST aims to glimpse the first luminous objects that have ever formed in the Universe. Even if the light from these stars was emitted in a very high energy level and have a short wavelength, the redshift will get the wavelength across the visible range, and reach the infrared range. Therefore, JWST will conduct investigations using infrared images.
In this article, we’ve talked about the James Webb Space Telescope, which was originally scheduled to launch in 2007, but its launch date was delayed by 14 years to December 22! No matter what, it will be the most powerful telescope ever made, and it will hopefully change our understanding to the very early stages of the Universe.
References and Credits
- (n.d.). The Launch – James Webb Space Telescope. Retrieved November 21, 2021, from https://jwst.nasa.gov/content/about/launch.html
- (n.d.). Orbit – James Webb Space Telescope. Retrieved November 21, 2021, from https://webb.nasa.gov/content/about/orbit.html
- (n.d.). Super-tough sunshield to fly on James Webb Space Telescope. Retrieved November 21, 2021, from https://www.esa.int/Science_Exploration/Space_Science/Super-tough_sunshield_to_fly_on_James_Webb_Space_Telescope
- Lynn Jenner. (2015, February 25). Webb Conversations: It’s All About Infrared – Why Build the James Webb Space Telescope. Retrieved November 21, 2021, from https://www.nasa.gov/content/goddard/webb-conversations-its-all-about-infrared-why-build-the-james-webb-space-telescope
- James Webb Space Telescope (JWST). (2021, November 13). James Webb Space Telescope Deployment Sequence (Nominal). Retrieved November 21, 2021, from https://www.youtube.com/watch?v=RzGLKQ7_KZQ
- Northrop Grumman. (2017, January 25). James Webb Space Telescope Launch and Deployment. Retrieved November 21, 2021, from https://www.youtube.com/watch?v=v6ihVeEoUdo
- (n.d.). James Webb Telescope Overview | NASA. Retrieved November 21, 2021, from https://www.nasa.gov/mission_pages/webb/about/index.html