The Stunning Science of the James Webb Space Telescope
The Graduate Center’s K.E. Saavik Ford describes how it works and why its images are so important.
The world was awestruck this week with the first-ever images from NASA’s James Webb Space Telescope. The telescope peered into never-before-seen corners of the universe, revealed by light that had traveled across space from 13 billion years ago.
The images include the Southern Ring Nebula, a kaleidoscopic cloud of colorful gas surrounding a dying star; Stephan’s Quintet, a group of galaxies churning together near a supermassive black hole; and a new exoplanet with telltale signs of a water-filled atmosphere.
The agency also shared an astonishingly vivid image of the Carina Nebula that revealed the early phases of star formations, and a deep field image of a galaxy cluster, named SMACS 0723, located an astounding 4.6 billion light-years away from Earth.
NASA scientists said the images, released Tuesday, far exceeded expectations. The Graduate Center spoke to Professor K.E. Saavik Ford, (GC/Borough of Manhattan Community College, Physics, Astrophysics), a member of a team that built and developed instrumentation aboard the space observatory, to learn more.
The Graduate Center: What makes these images so sharp? What’s different about the JWST that allows it to take such clear images so far away?
Ford: There have been many comparisons of images taken of the same parts of the sky using the Hubble Space Telescope. James Webb Space Telescope (JWST) images are made at longer wavelengths, in the infrared, compared to Hubble, which mostly sees in the visible part of the spectrum. Longer wavelengths would actually mean images that were less sharp, except that with JWST we also got a much bigger mirror for catching the light.
Hubble's mirror is about the size of the back of a school bus; JWST's mirror is about as wide as a school bus is long. The images are also sharp because of how much total light is being collected by the giant mirror, so fainter details are seen more easily.
GC: How far away did the telescope allow us to see?
Ford: Because light travels at a fixed speed, when the light we see with our telescopes comes to us from far away, it has taken a long time to reach us. So, looking out in space is also a way of looking back in time. The most distant objects we see emitted the “oldest light” and in the deep field cluster image, some of the light was emitted by the most distant galaxies we're seeing over 13 billion years ago.
GC: What are your favorites images so far?
Ford: My favorite is probably Stephan's Quintet. The individual galaxies are gorgeous, and they're close enough that we can see amazing detail in each of them. Because four of the galaxies are involved in a galactic scale “car crash,” they're also changing through their interactions with one another. The JWST images will help us understand how this collision impacts the development of galaxies in our universe.
I'm also pretty fond of the deep field. At the scale it's usually displayed, I think the average person doesn't see what's so cool about it. It looks like a bunch of colorful dots and smudges, right? But if you zoom in to any one of those dots or smudges, they're all fully-fledged objects, and you can examine each of them in gorgeous detail because of the exquisite, resolving power of JWST.
GC: Do these images tell us anything we didn’t know? Do they help to solve questions?
Ford: Yes. We can see the structures of early galaxies in the deep field and start to understand how galaxies have grown and evolved at early times in our universe. The Stephan's Quintet has multi-color images of the active galaxy, a galaxy where a supermassive black hole is actively feeding on gas at the center. The particular colors were chosen to enable us to probe the gas flowing out from the center of the galaxy, and will require a bit more interpretation to understand fully.
I'd also like to highlight the ability of JWST to take spectra. These are like what you get when you take sunlight and pass it through a prism to make a rainbow — by separating out the light into different colors (or wavelengths), we can understand even more about the objects we're looking at. Spectra help us to measure what chemical elements are in distant objects through the unique spectral fingerprints of each substance, as well as other important things like how fast those objects are moving or how large a star is.
There are already a few spectra released, which is why I can say that the exoplanet WASP-69b has a lot of steam, as well as clouds in its atmosphere. And there are elements created in the explosions of dead stars already present in galaxies within about 600,000 years after the Big Bang. So, by 600,000 years after the Big Bang, some stars had already lived and died, and their exploded guts had managed to form a new generation of stars. It's extremely exciting.
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GC: What is it about JWST’s technology that enables it to take such incredible images?
Ford: That giant mirror is item #1. But besides that, we need a telescope that will be stable and can point accurately, capture the light on good cameras, block stray light from the Sun, Earth, and Moon, and operate unattended for at least a decade. (As of today, current conditions look like we should be able to do at least 20 years, but the mission requirement was 10).
Putting it all together into one spacecraft, and getting it to the cold, quiet spot that it’s currently orbiting at, that was what was hard. The support required to make best use of the giant mirror was the hard part. Thousands of people had to check each piece of the design, test the manufactured parts, integrate it, pack it, ship it, launch it — it's just a giant beast with a lot of moving parts. That was why it was so expensive.
It's a giant mirror, so big you couldn't find a rocket to launch it without folding it up to fit inside the ship. So, figuring out how to fold up the mirror and then unfold the mirror once it was in space, that's been the scariest, hardest tech. We're all so relieved it worked.
GC: What images do you hope to see from the telescope in the future?
Ford: I'm especially partial to the active galaxy NGC 1068, because that is data that I and my team will get directly. With our data, we'll be able to better understand how feeding supermassive black holes get their food, and what their eating habits do to the galaxies they live in. But there are also many other observations. I'm very much looking forward to seeing how early in the universe JWST will be able to probe. This first cluster image was just a warm up — at some point soon, we'll really stare deep at one spot and get an unbelievably detailed image.
K. E. Saavik Ford is a faculty member of Graduate Center Physics Ph.D. program and the new Astrophysics master’s program, which offers students a direct path to doctoral studies in astronomy and physics, and work in STEM fields such as data science and analytics.
The James Webb Space Telescope was developed in partnership with NASA, the European Space Agency and the Canadian Space Agency.
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