James Webb Space Telescope to offer humanity an unprecedented look at universe

Scientists hope launch of remarkable instrument will help explore previously ‘unanswerable’ questions

The world’s most complex piece of origami is about to unfold—and if it works, humanity will get an unprecedented look at the universe around us.

The James Webb Space Telescope is currently planned to launch Dec. 25 from the coast of French Guiana. Built by NASA, the European Space Agency and the Canadian Space Agency, it will open up in a series of complex maneuvers over the next six months—all in order to peer deeper into space and time than we’ve ever seen before.

“It will be an explosion of new knowledge,” said University of Chicago Prof. Jacob Bean, who co-leads one of the telescope’s Early Release Science projects. “We are going to be learning new things from all directions. Just in the first year, I think we’ll answer questions we’ve had for decades.” 

The telescope’s enormous array, consisting of 18 hexagonal mirrors, a sunshield, and its complement of four instruments, will unfurl like a flower once it’s in space. Known as JWST, it will orbit much farther away from us than the Hubble Space Telescope does—more than a million miles away from Earth, compared to just 340 miles for Hubble—and so it has to be much more autonomous. All of these are tremendous engineering challenges; thousands of scientists and engineers have been working on JWST for decades.

The project faced multiple delays during its development, in part because its mission is so much more ambitious than anything previously attempted. All those efforts, astronomers hope, will very quickly change the game. Several University of Chicago scientists are slotted to use the telescope in its first run of observations—to learn about the origins of our universe and how fast it’s expanding, about the planets that orbit other stars, and many other questions.

“JWST is a truly transformative instrument, and that’s a word I don’t use lightly,” said Prof. Mike Gladders, who is part of another science team tackling early JSWT observations. “It will allow us to both pose and answer questions that right now are simply unanswerable.”

All the light we cannot detect

The light from the earliest days of the universe is still traveling across space. Over time, as the universe expands, that light gets stretched out into longer wavelengths. JWST is designed to be able to see these wavelengths by examining the infrared spectrum.

“With JWST, we’ll get observations of the first stars and galaxies as the universe emerges from the ‘dark ages,’ as the first compact objects form and light up,” said Gladders. “This epoch is almost completely unobserved until now. We have only hints.”

Gourav Khullar, a Ph.D. candidate in the Department of Astronomy and Astrophysics, will use JWST to look at one such early galaxy, which was first discovered by a class of undergrad students at UChicago in 2020. This bright galaxy dates back to when the entire universe was just about a billion years old; the group hopes further observations will help paint a clearer picture of how objects like stars and galaxies formed out of the chaotic soup that followed the Big Bang. “With just one set of observations, there is so much potential to address a range of science questions: do galaxies in the early universe look anything like present day systems? How do stars form in distant massive galaxies?” Khullar said. 

Gladders agreed: “This epoch is the transition from a smooth, near-uniform universe to complexity. The switch flipped. This is the moment when stars and planets and ultimately, us and coffee cups and puppy dogs, become possible. JWST is an opportunity to fill in some of the last missing pieces of the cosmic narrative.”

Planets in other star systems

Another JWST specialty is exoplanets—faraway worlds circling other stars. In the past 20 years, scientists have rapidly become aware just how many of these exist; so far, they think there are other planets around at least half of all stars similar to our sun. But they still aren’t sure what these planets actually look like—icy like Uranus and Neptune, gas giants like Jupiter, green and watery like Earth, or something completely different.

JWST will give scientists an unprecedented ability to learn about these planets. The telescope will be able to characterize what gases are in a planet’s atmosphere; how warm or cold it is; and even produce a rudimentary map of how much its temperature changes with longitude.

“It’s going to be absolutely extraordinary for studying exoplanets,” said Bean. “So far, it’s kind of like we’re trying to sense an elephant, and until now we’ve been able to look at the end of a tail and maybe an ear. Now, we’ll more than likely be able to see the whole elephant for the first time. So maybe we’ll look at it and find out it’s not even an elephant—it’s a woolly mammoth.”

Expanding the universe

Wendy Freedman is a leading astronomer who specializes in measuring how fast the universe is expanding—and she’s hoping JWST can resolve a troubling question that’s arisen over the past decades.

“There is a lot of excitement in cosmology over the possibility that our current standard model of cosmology may be missing a vital ingredient,” said Freedman, the John and Marion Sullivan University Professor in Astronomy and Astrophysics. When astronomers measure how fast the universe is expanding around us locally, they come up with a slightly different number than estimates based on light from the beginning of the universe.

It’s possible the discrepancy indicates there is a fundamental chunk missing from our current understanding of the universe—or it could be some kind of sampling error.

Freedman has done seminal measurements of the local expansion rate based on several different kinds of stars in the past, and she hopes JWST can help find a definitive answer. With JWST, her group will be able to run measurements of three different types of stars taken from the same galaxies. “This will allow us to measure the Hubble constant with unprecedented accuracy,” she said, “and should allow us to determine if the current discrepancy is due to unknown new physics, or perhaps to as-yet-unidentified uncertainties in the measurements.”

Meanwhile, Asst. Prof. Alex Ji is hoping for a signal that two neutron stars have collided nearby. If the LIGO gravitational web detectors on Earth pick up the ripples from such a collision, JWST will swing around to point at that spot in the sky. This could tell us about the origins of many of the elements in the universe, which prior observations indicate are made in these violent collisions.

Every astronomer worldwide, no matter their field, is holding their breath as JWST makes its way into space. For them, it’s a once-in-a-lifetime opportunity to resolve questions that have puzzled scientists for decades or even centuries. But it’s also a gateway to the unknown.

“JWST will lead the way to new questions we hadn’t thought to ask yet,” said Gladders. “Whenever you open the door to an arena we’ve never been able to see before, there are always surprises. This isn’t just answering questions we have right now—it will push us to ask new questions we don’t even have yet.”