7 things you should know about JWST

NASA’s current astrophysics flagship mission, James Webb Space Telescope (or JWST) is the most powerful space telescope ever built. It blasted off at Christmas 2021 aboard an Arianespace’s Ariane V rocket from ESA’s French Guiana Spaceport, located in South America. It’s the most ambitious space telescope ever built and is going to rewrite textbooks. Here are 7 incredible facts you need to know about JWST –

1. It is a time machine!
   Consisting of huge shiny mirrors, it will be able to look as far as 13.5 billion years! The Big Bang happened 13.8 billion years ago. It was about 0.2 billion years after the Big Bang when the first galaxies started to appear. Ultraviolet and visible light emitted by the very first luminous objects has been stretched or “redshifted” by the universe’s continual expansion and arrives today as infrared light. Webb is designed to “see” this infrared light with unprecedented resolution and sensitivity. So, it will be seeking lights from the first galaxies in the Universe. Fascinating! Isn’t it?

Webb’s Sunshield (Credit : NASA)

2. It is the coldest space telescope ever built
   Infrared Radiation is basically heat, and JWST is so sensitive that it could theoretically detect the heat signature of a bumblebee at the distance of the Moon. Therefore it must make sure that it doesn’t detect it’s own heat! To tackle this issue, JWST is equipped with a five layered, tennis court-sized sunshield that acts like a parasol and separates the observatory into a warm, sun-facing side (about 230ºF) and a cold side (about -385ºF-233ºC). It’s made of kapton and the vacuum between the layers acts as an insulator.
3. It has golden mirrors!
   How fancy it might sound, NASA has a very practical reason for using gold plating on it’s mirrors. Firstly, to ensure the mirror is both strong and light, the team made the mirrors out of beryllium. According to NASA, our everyday mirrors normally have silver or aluminum in them but they are unsuitable owing to their inferior reflecting properties. Silver reflects 95% of the infrared light whereas aluminum reflects only 85% of the same in comparison to gold, which reflects 99% of all the infrared light that it encounters. Moreover, unlike silver, gold belongs to one of the few metals that doesn’t corrode, so it was the perfect choice. Behind each mirror are several motors so that the team can focus the telescope out in space.

JWST’s Golden Mirrors (Credit : NASA)

4. It is the most complicated space telescope ever made
   With more than 300 single item failure items, it will be the most complicated space telescope ever built. It is the most powerful telescope ever built, yet it was to fit into the 5.4 meter diameter rocket fairing of the Ariane V rocket. That was the largest fairing size available in any rocket. To cheat the fairing size limit, it was made to fold like origami before getting attached to the JWST. And that’s what made the JWST extremely complicated, with unfolding in space being the most challenging part of the mission.

The telescope in its folded form (Credit : NASA)

5. With Big Risks comes Big Rewards!
   The planning for JWST started back in 1996. They couldn’t start development right away, because the telescope was way ahead of his time and a lot of components required for the masterpiece was yet to be developed. So it took almost 25 years till the launch of the spacecraft. Moreover, it costs close to $10 billion! And as I mentioned earlier, unfolding the spacecraft will be very risky and if there are any problems, there would be no one to fix it! Even if a simple EVA is required, NASA will either have to use their SLS rocket, which would cost either $2 billion, and they’d have to wait for at least 2 years as SLS’s first un-crewed launch is yet to happen and is scheduled to launch no earlier than March 2022. Another way would be to wait for SpaceX’s starship to get ready for crewed flights, and according to SpaceX’s CEO Elon Musk, it’s not going to happen earlier than 2023. Eitherways, congress might cancel any rescue operations and it would be a huge catastrophe for scientists all around the world. (I know I’m going to far ).
   
   The JWST has 50 major deployments, 178 release mechanisms which will work to perform the 50 deployments, and all the deployments must go right! This clearly explains how risky the mission will be. But on the other hand, such a grand mission doesn’t seem possible without immense risks, and this risks would later pay off as it will let us see the universe much better than ever!
6. It will operate 1.5 million km away from Earth, much further than the moon!
   JWST will orbit the Sun near the second Lagrange point (L₂) of the Earth-Sun system, which is 1,500,000 km (930,000 mi) further from the Sun than the Earth’s orbit, and about four times further than the moon’s orbit. Near the L₂ point, the combined gravitational pull of the Earth and the Sun allow a spacecraft to orbit the Sun in the same time that it takes the Earth. Staying close to Earth allows data rates to be much faster for a given size of antenna. It will remain directly behind Earth, from the point of view of the Sun, allowing it to remain on our planet’s night side. Webb’s sunshield will always be between the mirror and our star.

JWST’s orbit (Credit : NASA)

7. It will be way more superior than Hubble Space Telescope!
   What you might have guessed by now is the fact that JWST is way better than Hubble, and you are right! Hubble Space Telescope has a primary mirror of diameter 2.4 meters, close to 1/3rd of JWST’s giant primary mirror of 6.5 meters diameter. It is so big, that it was divided into 18 segments. and the whole mirror was folded before being launched. Here’s a video you should watch to understand the size difference between JWST and Hubble.

Credit : NASA

The Hubble Space Telescope was launched in 1990, and it still remains active. After it became perfectly operational, it changed astronomy forever! It discovered different galaxies, black holes etc. Moreover, it also detected a number of exoplanets as well. Hubble gave the next big push of discovery the whole astronomical society was waiting for! Moreover, Hubble also studied the outer planets of the solar system as well! With JWST being more powerful, scientists all around the world are counting on the Webb Telescope. The coolest part being that, Webb won’t discover exoplanets, but rather it will study the exoplanets which are already discovered! With Webb, humanity will get another eye looking at the universe! Let’s hope it successfully reaches to orbit and deploys in space without any issues. Check this website to know more about the telescope and to track the mission.

Ad Astra Pro Terra!