Utah scientists play key roles in the Webb Telescope, before and after launch
It’s hard to know exactly what scientists will learn when the James Webb Space Telescope launches later this week. But they have high hopes.
If the JWST is anything like the Hubble telescope before it, Weber State physics professor Stacy Palen says we’re on the verge of revolutionizing our understanding of the universe.
“Scientists are basically all in agreement that [Hubble] was a discovery machine,” Palen said. “It did way more than we ever expected and could even be in the conversation about the most important scientific instruments ever.”
It helped astronomers pinpoint the age of the universe down to around 13.8 billion years and discover that it’s not only expanding, but doing so at an accelerating rate. The observatory also opened up entire new fields of study into things Palen said were previously thought to be both well understood and utterly uninteresting.
“It's so interesting when we open up a new little window on the universe and look through it for the first time. We always see stuff we didn't expect to see even about objects that we thought we knew,” she said.
Utah’s role in the groundbreaking technology
The Webb telescope promises to do all that and more. Webb stands about three stories tall and is as big as a tennis court. Its mirrors are about six times the size of Hubble’s and it’s 100 times more powerful.
That presented an unprecedented technical challenge, requiring a global collaboration that spanned 14 countries and 29 U.S. states.
Utah contributed several key pieces, including the beryllium used to construct the telescope’s 18-hexagonal mirror segments. It was mined from Spor Mountain, one of the largest sources of the rare metal in the world.
Charlie Atkinson, who has overseen key aspects of production for NASA contractor Northrop Grumman since 1998, said beryllium was chosen for its extremely light weight, strength and ability to maintain its shape in super cold temperatures. It’s one-third the weight of aluminum but six times stronger than steel, able to withstand collisions with tiny space particles.
Atkinson was also in Utah when Magna-based aerospace manufacturer Orbital ATK — since acquired by Northrop Grumman — built the crucial backplane structure that holds the telescope’s mirrors and optical instruments in place.
It’s designed to keep the 2.5 tons of hardware essentially motionless through a bumpy rocket ride. If any of the mirrors move more than 1/10,000 the width of a piece of hair, the entire telescope could be useless.
“Never before had that been asked of a composite structure,” Atkinson said. “Never mind, let’s do it at cryogenic temperatures.”
A new perspective on the universe
Webb is unique in that it will be able to detect some of the faintest light waves in the infrared spectrum, which neither humans nor Hubble can see.
Seeing that kind of light will give astronomers a new perspective on the universe, allowing them to peer more closely into our own galaxy, look for signs of life on distant planets and examine the first stars and galaxies to form in the universe billions of years ago.
“The overall goal is really to piece together that picture of — how do we get from the beginning of the universe to now?” said University of Utah astronomer Anil Seth. “And then maybe also what's going to happen in the future?
Seth will be one of the first scientists to get time with JWST and one of just two in Utah. His proposal was selected out of more than the 1,000 that were submitted to use the telescope in its first year.
He’ll be looking at the invisible imprint of black holes on nearby galaxies. Having that data will help astronomers look for black holes in smaller galaxies much older and farther away to learn more about how they form and the role they play in galaxy formation.
“We need to understand the populations of black holes, say, at different times in our universe,” he said. “When were the black holes growing the fastest? How long did they grow for? Those sorts of questions become important.”
Studying the early universe
Seth’s colleague at the U, astronomy professor Zheng Zheng, will also get some time with the telescope in its first year.
He’s studying an era in the early universe known as reionization, following the so-called cosmic dark ages. For much of that time — hundreds of millions of years — there was no light in the universe, just a hazy fog of hydrogen atoms.
Within the fog, though, were pockets of dense material, which grew and eventually collapsed to form the first stars and galaxies.
Zheng said at that point, ionized bubbles began to form around those stars, almost like a pot of boiling water. The bubbles continued to grow and combined until eventually the entire universe became ionized.
He said it’s an important phase in the universe’s evolution. But astronomers don’t know much about it. What they do know has mostly been understood through computer simulations. Webb will allow Zheng and others to test their theories and, hopefully, observe the process directly.
“If we find a connection between bubbles and the galaxies, we basically will learn about the source that's responsible for this reionization process,” he said.
Winning observation time
To earn time on the telescope, Seth said proposals have to include precise measurements of where to look in space and for how long. Because JWST is so big, it takes about 45 minutes to rotate it around from one side of the sky to another.
Measurements from each proposal had to be carefully coordinated to make the most efficient use of the telescope. Seth said he’s getting about 32 hours of total observation time and expects the first data to come in around July.
Until then, he said it will be hard to relax.
No going back
It’s not just the launch JWST has to survive. Its massive size forced engineers to figure out how to fold it up so that it could fit inside a rocket and then unfurl itself as it drifts out to its final destination about a million miles from Earth.
That distance is too far for astronauts to service, which they could do — and did several times — for Hubble, most famously when its first images came back blurry.
While every conceivable aspect of the project was tested, not everything the telescope will experience up in space can be replicated on Earth, said Scott Willoughby, JWST program manager for Northrop Grumman.
He says the tennis court-sized sun shield that protects the telescope from unwanted heat is so big there was no facility on Earth that could test it. So they built a model one-sixth the size and tested that.
“Will something be a little bit different in there?” he said. “Maybe. But that’s also why you put margin in. Anything you don’t test … you actually tend to include a higher margin of safety in it for more uncertainty.”
He said they’re confident they’ve checked every box and now the mood is mostly one of excitement at the launch site in Kourou, French Guiana. But there are no second chances on this mission.
If anything does go wrong with JWST, it could wind up a $10 billion piece of space trash.
For physicist Stacy Palen, there’s something beautiful about that.
She said there’s nothing like uncovering the mysteries of the universe that can make humans feel so accomplished and so insignificant all at once.
“On the one hand, this might be the most important thing to happen in astronomy this decade,” she said. “And on the other hand, the universe won't care.”