Author: Carrera Ortiz

With the recent launch almost a year ago of the James Webb Space Telescope [JWST], alongside the beautiful pictures released from this grand telescope, you may have seen some exciting hype around the “premier observatory of the next decade” (NASA – JWST). In case you have missed out, here are some of the images from JWST!

Though it is incredible to be able to view space in such detail, the telescope is more than just an incredibly expensive camera. For astronomers, physicists, and enthusiasts/curious minds alike, I will detail the mission of JWST, how it got its name, and the great feat of engineering that this telescope symbolizes.
The James Webb Space Telescope is the result of an international collaboration between many space agencies, namely NASA, ESA (European Space Agency), and the CSA (Canadian Space Agency) [1]. The JWST is expected to last a minimum of 5 years, though there is hope that it can last at least twice that long. Be sure to temper your expectations for that longevity, as this telescope is much further away from us than Hubble, meaning that though we can service Hubble should issues arise, JWST is much too far away to be able to fix it manually. We simply must trust that the engineering that has gone into its creation is enough to protect it from all that may happen to it so that it can last as long as possible. The longer the JWST lasts, the more information on our universe we can collect! Many researchers, at all levels, interested in our universe have slated time with the telescope. In general, the JWST is largely able to explore the early universe, galaxies over time, the lifecycle of stars, and other worlds/exoplanets. In its first cycle, the largest category that JWST will spend its time on is galaxies and the inter-galactic medium (IGM), as shown in this pie chart created by NASA and P. Jefferies (STSCI). But, with all this time and all there is hidden in the universe for us to discover, the possibilities for JWST are essentially limitless.

Previously, one of the most known telescopes was the Hubble Space Telescope, named after Edwin Hubble – a notable astronomer that elevated the field of astronomy and cosmology with his observations. Another key observatory of our time is the Chandra X-Ray Observatory, named after Subrahmanyan Chandrasekhar, who from my studies here at Tech, was key in our understanding of the lifecycle of stars and how mass plays a role in their evolution. In his study of white dwarfs, he discovered what is known as the Chandrasekhar Limit – an upper limit on the mass of a white dwarf. With such key figures having their names associated with these feats of engineering, the question is: Who is James Webb, and what has he done to have this telescope named after him? Surprising as it may be, James Webb is actually not an astronomer (or physicist or scientist, for that matter). James Webb was a director of NASA, and according to Webbtelscope.org, he is “best known for leading Apollo, the series of exploration programs that landed the first humans on the Moon” [2]. He played a crucial role in getting public and governmental morale for the program, even through tough situations, such as the unfortunate deaths that occurred during the Apollo 1 mission. James Webb is credited for NASA being as huge as it is today, as he laid the groundwork for it to expand into so many missions even past Apollo. Despite this, the naming of the telescope after James Webb was not without its opposition. From history, you may remember that during the era of the Space Race where we sought to “outrun” Russia with our STEM programs, especially that of leaving Earth, there was also a great fear around communism, leading to the “Red Scare”. Less well known, but with similar animosity and paranoia, was the “Lavender Scare”. The Lavender Scare was essentially the paranoid masses wanting to purge any LGBTQ+ individuals from the rest of society due to homophobic thoughts on the morality and deserved (in)equality of certain people. In fact, during Webb’s reign as a director, a budget analyst was fired for indecent conduct, solely based on the assumption of homosexuality. Many argue that even if he did not directly influence this firing, he as Director had enough influence on the agency to encourage the moral obligation of taking a stance against homophobia. Petitions were made hoping to strike Webb’s name off the telescope, with many suggestions for replacement, such as Sally Ride – the first American woman and lesbian in space – among many other suggestions. Though investigations have not shown strong evidence that these claims are true, it is considered by many at best a complicated history with other figures and ideals that could replace the name. Though the name is not changing, I personally prefer calling it the “Jelly Welly Space Telly” as a fun and exciting name that does not relate to possibly homophobic individuals. More formally, I will always refer to it as JWST, as you will see in this article due to my personal stance on the matter.
Moving onward, we have a glimpse of the possibilities of what this telescope can accomplish, or at the least, some amazing images of what it can see in space, but what makes this telescope so much more intense and exciting than others, like our good ole’ Hubble Telescope? Other than being almost 10x as expensive at 10 billion dollars, the JWST is extremely precise in many aspects, and an intense thermodynamical achievement as the instruments require. Along with the distinct gold hexagonal mirrors and its sun-shield base, the cameras/instruments carried by the JWST are the NIRCam (Near-Infrared Camera), NIRSpec (Near-Infrared Spectrograph), NIRISS (Near-Infrared Imager and Slitless Spectrograph) and the MIRI (Mid-Infrared Instrument). You may have noticed that each of these instruments are focused on the infrared. This is a key component that should allow us to see a different perspective and farther into our universe – ideally around 13.5 billion years into the Reionization Epoch, which I will cover more in a future article. For now, it is important to understand that essentially, looking in the infrared region is similar to looking at heat – meaning that the telescope itself must remain incredibly cool to avoid any corruption of its images by surrounding heat. The JWST is an incredible collection of work from the launch vehicle, its image processing units, its electromagnetic systems, cooling systems, and its unmistakable golden mirrors and sunshield. This system – originally folded for storage before it launched into space – will be at a special point in space called L2. L2 is a Lagrange Point 1.5 million kilometers from Earth. For reference, our Hubble telescope is around 570 kilometers from Earth, and our Moon is around 384,000 kilometers from Earth. Though far away, it is a crucial point in space that allows for a long-life for our special telescope. The Lagrange point, which is not a reference to my hometown surprisingly enough, is a point in space where a satellite may remain in orbit relatively stable due to the balance of gravitational energy between 2 objects. With this stable orbit, the JWST is able to conserve fuel usage by using very minimal amounts to remain in one area. This area specified by L2 uses Earth to block the light from the Sun, to help with the cooling required by the telescope. Other points are key for different missions. The L1 point would be incredibly damaging to JWST but is an ideal spot for a telescope that would be used to study our Sun.

If it hasn’t been emphasized enough, the JWST must be kept at EXTREMELY cool temperatures. In order to operate correctly, the dark side of the telescope must be at -233॰ C, or -388॰F. Even with the Earth blocking some sunlight, it is expected that the Sun will still dump about 200,000 watts of power onto the sunshield, and the engineers had the tough goal of ensuring that no more than 1 watt would get past. In order for a sunshield like this to work, it has a list of requirements, and ideally is also lightweight for the launch into space to go smoothly. The desirable properties of the sunshield are for it to be strong, resistant to degradation from solar radiation, stable over a large range of temperatures, and reflective [3]. The solution is apparently a high-performing plastic called Kapton, rolled into extremely thin sheets. This material crosses off each requirement except for its reflectivity. Luckily, the material was easily able to be coated in a thin layer of aluminum to add the reflective property to counteract the radiation. Layers of this material were created very specifically, with gaps to utilize the insulating and cold nature of space to help cool down the telescope even more. Additionally, these layers were angled relative to each other such that sunlight is deflected away from the dark side of the telescope and less heat is absorbed by the solar radiation. These layers also need to be protected from tears of possible impacts from micrometeorites. The tension in the layers is quite high, meaning that any rip that occurs could easily expand and ruin the integrity of the telescope, allowing heat to escape to the precious equipment. To prevent this, rip-stop seams were molded into the sunshield. Every possible parameter was thought of by the team of engineers that worked on this amazing telescope. Yet, the difficulty here isn’t over. In order to be stored in the rocket that would launch the telescope into space, many parts of the telescope were folded and meant to unfold in space. For a 10 billion dollar telescope, it is quite the gamble to risk it unfolding incorrectly, ruining the engineering put into place over 25 years. In just unfolding the sunshield, there are “over 300 single points of failure in this unfolding sequence,” [3]. Luckily enough, I can spoil it for you that indeed no failures occurred, but is an intense situation nonetheless.
Yet, the coolest part of the telescope is yet to come, and I mean that literally. From before, I mentioned that one of the instruments was named MIRI. This instrument is extremely sensitive, requiring an intense cryocooler to keep it at a mere 7॰K. This insanely cool temperature is achieved by intense physics. The cryocooler needs minimal to no vibrations and some electricity. To minimize vibrations, many pulleys and balanced weights are included so that every movement is precise and calculated. With electricity comes heat, and thus a need to separate some cool and warm air. Using basic principles of acoustics, the cryocooler involves a complex system. This complex system can be conceptually simplified using thermoacoustics, which utilizes the pressure and temperature relations in air and a standing wave to create a piston inside of horizontal cylinders. These cylinders contain a stack, which separates the cool and warm air, which allows attachments to expel the warm air into the sunshield which can dissipate the heat. This system is quite the expensive unit itself, and just an incredible physical process. It is shocking to me that we are capable of creating a system that can reliably keep something just a few degrees above absolute zero temperature.
Now, for one of the most distinct parts of the telescope. The golden mirror, composed of 18 hexagonal segments, at 6.5 meters in diameter. The hexagonal shape was chosen because it is “roughly circular, segmented mirror” with few gaps and six-fold symmetry [8]. Essentially, due to the necessary folding requirement, NASA needed a shape that could eventually be roughly circular so the image wouldn’t distort in any one direction, and that was symmetrical so that precise optical calculations could be made easier, thus the interesting shapes. The materials chosen for this were also quite different than that of Hubble, and much lighter to make its launch easier for such a far distance. The mirror surface is made of Beryllium, a material that is much easier to break than steel, but much harder to deform at a young’s modulus of 300 Gpa. Though it is not a reflective material, requiring a coating of gold that is 0.1 micron thick. Learning from past mistakes, the JWST mirror is programmable to avoid unserviceable optics issues. In the past, Hubble had major optics issues that were only able to be fixed due to its close nature. JWST does not have this advantage, so the ability to adjust on a scale of wavelengths of light to keep the primary and secondary mirror aligned is crucial to the mission being operable at all. The mirrors also have a Cassegrain focus hidden in the center, using a fine guiding system that almost constantly adjusts to remain focused on a guiding star that is always in its center of field of view. This image stabilization tool is incredibly precise, and is another key aspect of the amazing engineering that goes on in this telescope.
This new observatory has touched so many people and will inevitably lead to so many discoveries about our universe. The level of excitement that I and so many others have for what there is to discover from the data we can now collect is at such an all time high, there was no way I couldn’t write and share this with you. Indeed, this is just the start of what I will be sharing; I couldn’t fit all that excitement into one article! Honestly, I can basically write a textbook solely on this topic because there is so much information hidden in every release and I want it all to astound everyone else as much as it has for me. Here, I discussed how its made and the purpose of this new telescope, and soon I can’t wait to discuss in depth what this technology is actually bringing to the science table.



References:

[1] James Webb Space Telescope | NASA

[2] Webb Home (webbtelescope.org)
[3] The Insane Engineering of James Webb Telescope – YouTube
[4] The James Webb Space Telescope’s Cloud of Controversy – Viterbi Conversations in Ethics (usc.edu)
[5] NASA James Webb Space Telescope stirs controversy over name, LGBTQ discrimination – The Washington Post
[6] The Lagrange Points – Lucy Mission (swri.edu)

[7] (featured image) Artwork:Photographs:Webb Mission:James Webb Space Telescope Artist Conception (webbtelescope.org)

[8] Mirrors Webb/NASA