James Webb Space Telescope: Just in Time!
2022-07-21 / Karrie Berglund / JWST
If you’re at all familiar with the James Webb Space Telescope (JWST), you know there were many delays on getting it into space. Originally scheduled to launch in 2007, the JWST actually launched on December 25, 2021. The first set of images, released on July 12, 2022, prove that it was well worth the wait.
The JWST is a joint project spearheaded by NASA, with contributions from around the globe, including from the European Space Agency and Canadian Space Agency. Several universities and businesses in the USA and other parts of the world contributed, with a total team size of about 10,000 people.
An engineering marvel, the JWST is the successor to the beloved Hubble Space Telescope (HST). The JWST features a far larger mirror--about 6.5m wide versus 2.4m on the HST--composed of 18 smaller mirrors. The tennis-court sized sunshield, which keeps the instruments under about 50 degrees Kelvin/-370 degrees Fahrenheit so that the telescope can properly image in infrared wavelengths, also had to be folded for launch.
Take a moment to really think about the challenges involved with such a large space telescope: JWST engineers had to figure out how to fold these and other parts for launch, unfold everything once JWST reached its destination, and then individually adjust the components. Each mirror had to be aligned so that all 18 were working together--and that alignment was done from about 930,000 miles/1,500,000 km away.
In a Wall Street Journal article from July 8, 2022, Ben Cohen pointed out,
This was a project with almost no margin for error, and yet the risk of error was everywhere. There are more than 300 single-point failures in Webb’s system, meaning a malfunction in any one of those devices could have doomed the whole mission.
“On a Mars landing mission,” said Steve Jurczyk, formerly NASA’s highest-ranking civil servant, “you might have 70 single-point failures.”There were so many things that could have gone wrong, and yet it all functions beautifully. Everyone who worked—and continues to work—on this mission should be tremendously proud of the success.
Where Are the HST and JWST?
The HST has been orbiting Earth since April, 1990, about 340 miles/550 km above our surface. While the HST is still gathering wonderful data, the JWST's far larger light bucket, more sensitive instrumentation, and location mean that we are going to see farther away in space and thus farther back in time than we ever could before.
The JWST, as noted above, is about 930,000 miles/1,500,000 km from Earth. The JWST orbits the Sun, not Earth; it is positioned at the Sun-Earth L2 Lagrange point. This location allows the JWST to stay in line with Earth as it moves around the Sun.
Along with the size of the telescopes and their locations, the fields of view are different as well. The famous Hubble Deep Field North from 1995 looked at a patch of sky near the Big Dipper that is about the size of the head of a pin held at arm's length. Although that patch of sky appeared from Earth to be completely empty, HST showed us it actually contains about 3,000 galaxies.
The infinitesimal part of the sky that JWST observed for its First Deep Field contains galaxy cluster SMACS 0723. That galaxy cluster on its own is composed of thousands of galaxies – including the smallest, faintest objects ever observed. SMACS 0723, located near the center of the image, is about 4.6 billion light years from Earth. In other words, the light we see from SMACS 0723 was emitted not long before Earth formed. In Webb’s First Deep Field the field of view is about the size of a grain of sand held at arm’s length.
Go ahead, hold out your arms. Imagine that you are holding a grain of sand between your thumb and forefinger in one hand and a pinhead in the other hand. Of course both are small, but you would actually be able to see the pinhead.
SMACS 0723 is so massive that it acts as a gravitational lens, helping us see even deeper into space by bending light from galaxies behind the cluster. Some of these gravitationally lensed galaxies are more than 13 billion light years away. If that doesn't take your breath away, I don't know what will. And the JWST is just getting started.
For me personally, the JWST images were rejuvenating. At a time when bad news seems to be the only news reported, with war in Ukraine raging on, when political divisions in the US run both deep and wide, I really needed the JWST to succeed (and boy did it ever succeed!). I needed an incentive to think about more than just myself and the things that divide me from others. I needed a reason to look at the questions that people have been asking for millennia: How did the universe begin? What did the early universe look like? Are we alone in the universe?
I happened to be exhibiting with our portable planetarium at a conference of physics teachers during the release. While I expected the conference attendees to be interested in seeing the JWST images in our dome, I found that many of the security guards and other convention center staff were also engaged in and knowledgeable about the science. I was reminded once again that astronomy has the power to connect us no matter how many other forces are trying to push us apart. After all, no matter where we live, what our occupations are, etc., we all see the same Moon; we all get light and heat from the same Sun.
I am of course not the only one to have an emotional reaction to the first images. NASA's deputy administrator, Pam Melroy, commented, "What I have seen moved me, as a scientist, as an engineer, and as a human being." Jane Rigby, operations project scientist for JWST at NASA's Goddard Space Flight Center, said she had a feeling of "...people in a broken world managing to do something right and to see some of the majesty that's out there."
Psychology Today even published an article on their website entitled Webb Telescope Can Inspire Hope When We Need It Most. The opening paragraphs from that article sum up my feelings perfectly:
In a world filled with too much bad news (e.g., the global pandemic, war, social and legal injustice, and political turmoil), NASA provided a much-needed boost to our spirits by sharing the first images from its James Webb Space Telescope this week.
Consequently, people from diverse walks of life viewed these images with giddy excitement. In addition to providing a psychological lift for us all, the Webb Telescope highlights ways to bring people closer despite so many societal forces fighting against human unity.
Scientists are going to be studying these first JWST images for months if not years; the images are so rich and layered that it is going to take time to analyze all of the information in each. All the while JWST will be collecting new data, helping us learn more and more about our universe.
I can hardly wait to what images this magnificent instrument provides next! I extend my gratitude and congratulations to the entire James Webb Space Telescope team for the tremendous job you have done and continue to do. I really needed that...
If you'd like to learn more about the James Webb Space Telsescope, here are some links: