5 Cool Things About The James Webb Space Telescope

Last year around Christmas, I was invited onto a Danish TV show to talk about the launch of the James Webb Space Telescope, JWST. I was invited via e-mail and reading this fancy invitation over and over made me realize that I knew absolutely nothing about JWST. So, I ended up declining the invitation.

Fast forward to now where I have spent my time learning about JWST! I want to share some of this mind-boggling information with you, because it turns out this space telescope is (of course!) amazing and will (for sure!) revolutionize our understanding of space and all the weird spacey things in it.

Below, I have listed 5 things that I think are super-cool about the JWST. But before we jump in, let’s get a quick overview of this space observatory that was launched only a few months ago.

JWST – A Brief Overview

The development of JWST began in 1996. It is a NASA-led collaboration between NASA (US space agency), ESA (European space agency) and CSA (Canadian space agency).

The initial plan was to launch the telescope to space in 2007, but this deadline was subject to several delays and near-cancellations of the entire project.

It got its name after James Webb (1906-1992), NASA’s administrator who led the Apollo missions. At first the observatory was called Next Generation Space Telescope, NGST, but it was renamed in 2002 to honor James Webb.

The purpose of the telescope is to study deep space, the early universe galaxies, our own solar system and even provide detailed observations of the exoplanet atmospheres. This is a broad range of scientific objectives, as distant galaxies and our solar system are normally considered to be very far apart in terms of astronomical observations.

The JWST will observe mainly in the infrared part of the electromagnetic spectrum, but it can also pick up signals in the optical range of red and orange.

The JWST is the world’s most powerful space telescope and it will out-compete the Hubble space telescope by great lengths. It’s truly a work of art.

Now, let’s have a look at some of the most awesome features of this magnificent telescope.

1: JWST Is Sensitive To A Broad Range Of Infrared Radiation, Making “Invisible” Objects Visible

The JWST will observe mainly infrared light. This is what we normally call heat radiation and is perhaps not spectacular in itself, but the range of wavelengths it will cover is impressive.

The observatory can detected wavelengths from 0.6 μm to 28 μm. For comparison, the diameter of a human hair is around 50 μm, so this telescope will collect light-rays that have a wavelength a bit shorter than the thickness of a human hair.

It might sound like these rays are very small, but in physics these are actually considered to be quite long. The optical range of light, that is the light we can see with our eyes, have a much shorter wavelength. X-rays and UV-rays are even shorter.

These long waves from space carry so much good information with them, that we can not collect with Hubble as its instruments “only” could collect wavelengths up to 2.5 μm. With JWST going all the way up to 28, this is almost 10 times longer waves and hence way more information than we got previously from these regions.

This emission range is interesting for several reasons.

First of all, this part of the spectrum is generally difficult to observe from ground because our atmosphere absorbs this part of the spectrum from space. As a radio-astronomer myself, I have scratched my head over this many times. Earth’s atmosphere protects us from damaging radiation from space, but it also absorbs a lot of the information-carrying light that we need in order to understand what is happening in some of the most complex regions of space like star forming regions or faint galaxies.

Secondly, infrared radiation is emitted from the violent creation of the first galaxies in the universe. Or – that’s not entirely true. But when we receive the light from these galaxy formation events, the waves will be shifted towards the infrared part of the spectrum, even though it was originally emitted as the much more energetic UV-light. This is because the universe is expanding.

The range at which JWST observes is amazing.

2: JWST Will Observe From Lagrange Point, L2

JWST is located 1.5 million km from Earth (in the opposite direction of the sun from Earth). In comparison, the Hubble space telescope is located at “only” 550 km above the surface of the Earth. JWTS is truly far away. It is located here because this point is a Lagrange point.

A Lagrange point is a stable point for a small object (JWST) that is influenced by two massive objects (Sun and Earth). The Earth and Sun-duo has five Lagrance points, and JWST is located at one of them.

L2 is favorable location for multiple reasons. Living around L2 JWST will have the sun, Earth and moon on the same side at all times. This means that the telescope’s sensitive instruments will not be exposed (affected or damaged) by heat radiation from these objects.

This is quite a big deal because normally our solar system has so many objects in it, that at some point the telescope would be facing a close heat-emitting object. In such a case the shield would need to be dynamic so it could move to a shielding position.

This way, with the same side always facing the moon, Earth and sun, the telescope is way easier to design so the detector is always shielded from heat radiation and kept cold.

3: JWST Has A Sun-shield With SPF 1 Million

This leads me to the third point of awesome. The sun-shield. In order to shield off the heat radiation mentioned above, the JWST has a sun-shield composed of five layers, each the size of a tennis court. They will shield the telescope from heat and thereby protect the detector so that it does not get damaged or interrupt the delicate observations required to pick up faint signals from distant galaxies.

The shield is made of five layers instead of one thick layer. One thick layer would, over time, conduct heat from the sun-facing side to the detector. Five layers with vacuum between each isolates much better and keeps the heat where it should be: far away from the detector.

4: JWST Was Folded 12 Times To Fit Inside The Space Launch Vehicle

Continuing the topic of the sun-shield: In order to fit a huge tennis court sized shield inside the launch vehicle the shield needed to be folded 12(!) times.

It was the so-called Ariane 5 that had the honor of bringing this 10 billion dollar space telescope off the surface of the Earth. Ariane 5 is a European space launch vehicle that can bring heavy stuff to space. It was a part of the European contribution to the project and (I think!) one of the reasons why Space X was not chosen.

Ariane 5 was chosen around 20 years ago (back when the launch was expected to not take two more decades) because it was the only vehicle that met NASA’s requirements. Additionally, an agreement was made between NASA and ESA that while ESA delivered the launch vehicle, NASA would give European scientists 15% of the observation time once JWST was launched.

Choosing Space X wasn’t even an option back then, and I am also not sure it would be chosen if they were to re-decide today. After all, the launch vehicle is a big contribution from ESA, so by removing that, the European contribution would slim down.

I think this point is interesting, because it illustrates how big a role small and practical issues play even for a huge and impactful project like the JWST.

5: JWST Will Start Science Operations In 2 Months

The last cool thing I want to highlight in this post, is the fact that science operations are expected to start already in two months.

The JWST was launched on December 2021 at Christmas and half a year later it’s ready for science observations.

According to NASA, the space observatory has completed step 7 of 7 that were needed to align the telescope. This leads the telescope into its final preparation stage before being ready for science missions this summer.

This space observatory is utterly mind-blowing and I have no doubt it will bring with it new and revolutionizing insights about space and the early universe. And the solar system and exoplanets. And any of the other projects planned for this observatory.

This is not the last post I will write about JWST!


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