NASA’s new James Webb Space Telescope
The James Webb Space Telescope will travel 1.5 million kilometres from Earth and look back thirteen billion years.Illustration by Jonathan Djob Nkondo.
Rivka Galchen, NASA’s New Telescope Will Show Us the Infancy of the Universe, The New Yorker, 9 August 2021
Twenty-five years and ten billion dollars in the making, the James Webb Space Telescope will enable scientists to see deeper into the past than ever before.
Next month, the James Webb Space Telescope is scheduled to take a slow boat from Los Angeles, spend a few days traversing the Panama Canal, and arrive at a spaceport in Kourou, French Guiana. The telescope will have been twenty-five years and ten billion dollars in the making. Thousands of scientists and engineers from fourteen countries will have worked on it. It could have flown, sure, but it’s a tight squeeze—plus the telescope weighs seven tons, and Kourou’s airfield is connected to its spaceport by seven bridges not built to endure such a load. The telescope will be put into Ariane 5, a European rocket named for a mythical princess who helped a man she loved defeat the Minotaur and escape a maze. Ariane 5 will carry the telescope some ten thousand kilometres in thirty minutes. The J.W.S.T. will then continue on its own, for twenty-nine days, toward a lonely, lovely orbit in space, about 1.5 million kilometres from Earth, where we will never visit it, though it will stay in constant communication with us. From Earth, it will appear ten thousand times fainter than the faintest star.
On its way, the telescope will slowly unfurl five silvery winglike layered sheets of Kapton foil, about as large as a tennis court. These sheets, each thinner than notebook paper, will function as a gigantic parasol, protecting the body of the telescope from the light and the heat of the sun, moon, and Earth. In this way, the J.W.S.T. will be kept nearly as dark and as cold as outer space, to insure that distant signals aren’t washed out. Then eighteen hexagons of gold-coated beryllium mirror will open out, like an enormous, night-blooming flower. The mirrors will form a reflecting surface as tall and as wide as a house, and they will capture light that has been travelling for more than thirteen billion years.
This is the hope, at least.
“Oh, gee, I worry all the time,” said Marcia Rieke, an infrared astronomer based in Tucson, who has devoted much of the past two decades to the J.W.S.T. “Even the rocket, which is the most reliable rocket out there, it still has some tiny chance of exploding at launch.” Rieke, who has astrology-blue eyes and a no-nonsense ponytail, is the scientific lead for the near-infrared camera, known as the nirCam, which is one of four main research instruments on the telescope. She is an expert on the formation of galaxies, and the nirCam will allow us to see light from billions of years ago, when the earliest galaxies and stars were formed. I spoke with Rieke over Zoom, where she had as a background a lunar eclipse she photographed in Sabino Canyon, which is near her home but looks like it’s on Mars. “I’ve spent decades in this field, and there’s still so much I don’t know,” she said.
In 2017, Rieke and her team went to the Johnson Space Center, in Houston, where tests would be performed on the nirCam and other Webb instruments. They wanted to expose the telescope to the extremely cold conditions of outer space. Hurricane Harvey hit while they were there. “While I was at the airport waiting to fly out to Houston, I was watching the forecast and fortunately was able to change my car rental to an S.U.V.,” Rieke said. “So I was able to ferry the members of the team between their hotels and the Space Center. They brought in really nice catering for us. I’m not sure how they managed that.” Imagine sealing one’s gold-plated work of decades in a giant pressure cooker and then pouring liquid nitrogen on top of it—that resembles the exposure test. The telescope was in Chamber A, the gigantic vacuum chamber at the Space Center where the command module for Apollo was tested. Remarkably, Rieke’s team accomplished its mission. Rieke has seen the J.W.S.T. survive not only Hurricane Harvey but also numerous threats of cancellation, along with delays that have serially shifted the launch from an original date of 2010 to late 2021. I asked Rieke what she was most looking forward to seeing. “I’m looking forward to seeing that it works,” she said. “I’ll start sleeping better about thirty days after it’s been launched. Launch isn’t even the riskiest step in deploying the nirCam.” Once the telescope is up and running, Rieke will return to studying events that happened in our universe billions of years before Earth was formed.
It’s easy to forget that light takes time to travel. But when we see the moon we are seeing it as it was 1.3 seconds earlier; Jupiter we see as it was forty minutes ago; the Andromeda galaxy—the nearest major galaxy to ours, and the most distant object we can see without a telescope—2.5 million years ago. “My students are often frustrated to think that they can’t see the things in space as they are today,” David Helfand, an astronomer at Columbia University, said. “I tell them it’s this great advantage. It means that the universe is laid out like a book. You can turn to any page you want. If you want to see ten billion years into the past, you look out at ten billion light-years away.”
Helfand, a former president of the American Astronomical Society, looks like Socrates. He attributes much of his success in life to a background in theatre, and he spends a lot of his time teaching science to nonscientists—the only prerequisite for his perennial class Earth, Moon, and Planets is “a working knowledge of high-school algebra.” He taught me about the J.W.S.T.
Most of the light spectrum is not visible to the human eye. When we look up at the night sky, it’s as if we were listening to Rachmaninoff’s Second Piano Concerto with ears able to hear only the occasional middle C and maybe a tinny D. We have no biological receptors for radio waves, or microwaves, or ultraviolet radiation, or infrared radiation. If an object is moving away from us—and most everything in the universe is, because the universe is continuously expanding—the wavelength of its light is, in effect, stretched out, eventually rendering it infrared. Helfand said, “The atmosphere blocks out a lot of energy—that’s why we can live on Earth. But it’s not good for astronomy. And our atmosphere is particularly ugly for infrared.” On Earth, there are a number of telescopes larger than the J.W.S.T., but they can’t see the range of infrared light with the level of resolution and sensitivity that the new telescope will achieve.
“It will have many capacities, but the two big ones are ‘Very Far Away’ and ‘Very Close,’ ” Helfand said. The Very Far Away component will look back about 13.5 billion years, to when the universe was some quarter of a billion years old. “If you compare the universe’s life to that of a human, that’s like seeing the universe at, well, we’d have to calculate it, but it’s seeing the universe as a baby,” he said. After the big bang, the universe was a nearly uniform soup of matter and radiation. But by the mysterious epoch that the telescope will examine—sometimes called the Dark Ages—gravity had managed to amplify tiny irregularities in that soup, causing a kind of clumping. “So what we are on is the quest for the very first stars.” When did they turn on? What are they like? Did stars form before galaxies? How did black holes with masses millions of times greater than that of the sun form so quickly?
“The Very Close capacity is in some ways the most exciting,” Helfand told me. “It’s about looking at planets that are not too different from Earth.” The J.W.S.T. will study exoplanets, or planets outside our solar system. Exoplanetology is a young field. The first exoplanet (outside science fiction) was discovered only twenty-five years ago. By 2005, about two hundred exoplanets had been found. Today, more than forty-four hundred are known, and it seems likely that such planets are ubiquitous. Though they don’t emit light, Helfand explained that “when these planets pass in front of a star they leave a sort of fingerprint,” and that fingerprint can be read for clues. The J.W.S.T. will be able to describe the atmospheres of these planets, possibly detecting free oxygen or other gases—potential signs of life.
Helfand told me this story of how he became an astronomer. His parents had no more than a high-school education. His father was a farmer who took a job at a factory in order to make more money, but, Helfand said, “the day he reached the age of retirement he went back to farming, because that was what he loved to do.” Helfand had a remarkable theatre teacher in an otherwise “strikingly mediocre” high school, and, when he went to Amherst on a scholarship, he assumed that he would study theatre. “I somehow hadn’t thought through that Amherst had only male students,” he said. He looked through the course catalogue to find courses cross-listed with women’s or coed colleges nearby. “And so there it was, an astronomy course, taught by a professor at Smith,” he said. “A very impressive German woman.” He also liked the material: “Not the sitting-outside-on-a-cold-mountain-freezing-my-butt-off part. I remember being very impressed by the phases of a binary star.”
Near the end of the semester, the professor announced to the students that she was going to take them to where “real astronomy” was done, and took plane tickets out of her bag. The students flew to Arizona, whose high desert, with its clear skies and relative lack of light pollution, has made it a popular site for astronomical observatories. At the end of a marvel-filled week, one of the astronomers, Bart Bok—for whom the largest telescope of the University of Arizona’s Steward Observatory is now named—was giving the students a lift and asked if any of them were thinking of pursuing astronomy as a profession. Helfand found himself raising his hand. “O.K.,” Bok said. “You’re testifying before the joint committees of Congress. How do you justify the spending of taxpayer dollars on the totally useless study of the universe?” This was the age of Apollo, and Helfand was well versed in the argument that unforeseen economic benefits accrued from the Apollo mission. He remembers mentioning spinoffs like microelectronics.
Bok told him that this was not the right answer. “He said it was like the opera, or poetry,” Helfand told me. “That the right response was because it was what distinguishes us as human.” Astronomy is worthwhile in the way that art is worthwhile. “And so that’s how I became an astronomer.”
This is not the first time that nasa has spent more than twenty-five years and vast resources on a project that might fail. At the end of the Second World War, the American physicist Lyman Spitzer saw how reliably German V-2 rockets worked, and was excited by the idea that something similar might be used to launch a large telescope into space. He wrote a report titled “Astronomical Advantages of an Extra-Terrestrial Observatory,” which was published in 1946. The idea didn’t attract funding until 1977. The project started out as the Large Space Telescope, and later became the Hubble Space Telescope, named for the astronomer Edwin Hubble, famous for his handsomeness, his basketball skills at the University of Chicago, and his discovery, in 1929 (using the telescope at Mt. Wilson, near Los Angeles), that each point in space is moving away from every other point—that the universe is expanding.
The Hubble telescope was finally launched in April, 1990, and it sent back fuzzy images of spiral galaxies that looked like melted glaze on a galactic cinnamon roll. Hubble wasn’t working properly. The glass of the mirror had been ground ever so slightly too flat. Although the error was considerably smaller in scale than the thickness of a hair, it proved to be highly consequential. Science could still be done with the hobbled Hubble, but it was a catastrophically expensive letdown. It had been only four years since the Challenger exploded on takeoff. Congress was initially skeptical of approving funding for a mission to repair the Hubble telescope.
But in 1993 astronauts looking like marshmallow men stepped out of a shuttle and into outer space, and, counter to the narrative drive toward disappointment, were able to fix the orbiting telescope. (It took eleven days, five spacewalks, two hundred tools, and a bit of improvisation to close some warped bay doors.) Hubble began to send sublime images that bore information about the stardust from which we are made (if you want to think of it that way). Hubble was transformational, enabling nasa to recover its aura of supernatural scientific prowess. It taught us that the universe was considerably older than we had thought; that there were plumes of water vapor emerging from an ice-covered moon of Jupiter; that supermassive black holes are real. In one of Hubble’s most famous images, it documented towering clouds of dust and gas in the Eagle Nebula where stars are being born.
The question now was where to point Hubble, and for how long. Thousands of scientists wrote competing proposals, hoping to be awarded even an hour of Hubble’s time. But ten per cent of the time was to be used at the discretion of the director of the Space Telescope Science Institute, which had taken over the operation of Hubble once it was in orbit. The director of the institute was Bob Williams, a quietly decisive figure, who thought that the telescope should spend more than a hundred hours staring at a blank and unremarkable patch of sky. He decided on a dark area near the Big Dipper’s handle, a spot no larger than that occluded by a sesame seed held out at arm’s length.
Many reasonable people believed this plan to be an absurd waste of a precious resource. “It seemed like every time nasa was on TV it was a disaster,” Williams said. “I remember watching Johnny Carson making jokes about Hubble.” Williams, who is eighty years old, is retired, though he remains active as a lecturer and a consultant. He recalled, “I said that if the inquiry failed to be scientifically useful I would resign. It had to be done.”
Between December 18 and 28, 1995, Hubble took several hundred shots of the blank patch of sky, with exposure times of up to forty-five minutes, allowing for the very faintest traces of light to show up. The photos revealed some three thousand galaxies. And the galaxies were unusual. Coming from so many light-years away meant that they were from a much earlier moment in the history of the universe. “The galaxies were younger and stranger—more uneven,” Williams said. They gave hints as to how galaxies were formed, and how they have evolved. In 1924, Edwin Hubble had discovered that there was at least one galaxy other than our own; the Hubble telescope revealed that there were billions of them.
Those photos, known as the Hubble Deep Field images, are among the most important and broadly recognized images in modern astronomy. “Discussions for what the next telescope would do started up,” Williams explained. A larger mirror would be able to capture more distant light. And a telescope that was cold—shielded from light and heat—and that had finer infrared capacity would see and learn more. “I also thought it was essential that the data would be available to everyone,” Williams said. “I’m very proud of having pushed for that.”
Williams was keen to share that his wife has devoted her life to working with children and adults with autism. “She’s the one in the family who makes the world a better place,” he said. “In some ways, what I do is—the word isn’t ‘selfish,’ it’s not that exactly. It’s about curiosity, about wanting to know.”
In February, 2017, I drove to nasa’s Goddard campus, in Greenbelt, Maryland. A variety of low-rise white buildings with the impromptu modular feel of a nineteen-sixties school campus decorated a landscape of green lawns, mild hills, and parking lots. The James Webb Space Telescope was scheduled to launch in October, 2018, and its parts were in disparate places: its mirrors and instruments were at Goddard, its sunshield was in Southern California, and smaller components were at various sites in Canada, Europe, and the U.S.
In a small office, I met John Mather, a tall, thin, modest, and very calm astrophysicist and Nobel laureate. Mather has been the senior project scientist for the J.W.S.T. since its inception, in 1995. He won the Nobel, with his colleague George Smoot, for working out the temperature of cosmic microwave background radiation—the afterglow of the big bang. “That work started out as my thesis project when I was in Berkeley,” he said. “It failed as a project. But it did later get us the pins from the King of Sweden and all that.”
Mather was finishing up his work on background radiation when he had an idea for a space telescope that folded, allowing a larger—and thus more powerful—telescope to be loaded into a rocket and deployed in space. “People laughed at that idea,” he told me. “I guess because it had never been done before.” A year later, the idea won nasa funding, “though the budget was ridiculously small,” Mather said.
“Our framing perspective with this telescope has been that there are no problems that are too difficult,” he continued. “If there’s no law of nature preventing us, then let’s give it a shot.” Many parts of the telescope emerged from design competitions. For the mirror, the J.W.S.T. required a design that would be able to withstand the cold of space, be relatively lightweight, and be made up of sufficiently small individual pieces. “I’m a little surprised that we ended up with beryllium mirrors,” Mather said. “There was another beautiful design, two sheets of glass separated by a honeycomb.” He demonstrated the parallel sheets of glass with his hands. His calm seemed briefly rippled at the thought of the design that never came to be. “But one day you decide,” he said.
“Our famous mistake with Hubble was using the same ruler for building and checking,” Mather went on, referring to the measurements that caused the Hubble mirror to be ground imperfectly. “We trusted the wrong ruler. So now we know not to do that.” He gave a small smile.
Mather spent much of his childhood in Sussex County, New Jersey, on a dairy farm. He recalls picking out fossils from the pebbles in roadside streams. He studied physics on a scholarship at Swarthmore, before going on to a Ph.D. in physics at the University of California, Berkeley. Mather told me that he had recently enjoyed reading Yuval Noah Harari’s “Sapiens: A Brief History of Humankind.” “I’m interested in very long stories,” he said. He feels that astronomers have the easy part of the question “Where do we come from?,” and that the more difficult part is left to those who study humans. “I’m also interested in the future,” he said. “Is it short, is it long? We have a billion years before the sun gets too hot. Will we populate other planets, or will we stay home?” Among the few decorations in Mather’s office are two license plates. One is a California plate with the number 2.725. The other is from LaGrange County, Indiana, for a “non-motorized vehicle” (which is intended for a buggy, but would apply to a telescope). The background temperature of the universe, which Mather calculated in his most celebrated work, is 2.725 Kelvin, and Lagrange points are places in space where the gravitational pull of Earth is balanced by that of the sun—places where telescopes can be set into steady orbit.
When the James Webb Space Telescope was conceived, in 1996, it was a ten-year, five-hundred-million-dollar project named the Next Generation Space Telescope. But Dan Goldin, the nasa administrator at the time, argued that the telescope ought to be more than just a little bit better than Hubble. The proposed size of the mirror was increased from four metres to six and a half metres. Hubble orbits three hundred and seventy-five miles from Earth; the J.W.S.T. will be a million miles away. That may sound like two guys comparing stereo speakers, but the changes have made the J.W.S.T. a potentially revolutionary instrument. In the mid-infrared regime, it’s several thousand times more sensitive than the next best instrument. In 2002, the telescope was renamed for James Webb, a former head of nasa, who many argue was the force behind President Kennedy’s moon shot, a project that Kennedy thought needed to appear useful to the military but that Webb said would be most powerful as an inspiration for American science.
Like a hungry ghost, the J.W.S.T. inevitably ate up funding from other space projects—several prominent space scientists signed a letter saying that it could be the end of planetary science, because it cost so much—even as it was repeatedly threatened to be turned away from the dinner table forever. Time after time, its launch was delayed, usually in one- or two-year increments.
Bill Ochs, who has been the project manager for the J.W.S.T. since 2010, was appointed shortly before the telescope was nearly cancelled by Congress. Ochs has a bright and easygoing manner. When I met him, at Goddard, he was dressed in a green sweater, and wore a lanyard with his I.D. card attached. “It was nobody’s fault—no one had done anything wrong,” he said. “But I was brought on to try to do a re-plan for J.W.S.T., to get from 2010 to launch—the costs, the schedules. It was very difficult and complex. I remember it mostly as trying to figure out what all the acronyms were. That’s a very nasa experience.” Ochs began his career as a contractor on Hubble, starting in 1979, and then served as an operations manager for the suspenseful repair mission.
Congress must regularly reappropriate funding for nasa missions—a tricky proposition for projects on multi-decade time scales, given that congressional values and power holders frequently change. In 2011, Representative Frank Wolf, a Republican, and Senator Barbara Ann Mikulski, a Democrat, held the relevant purse strings. The telescope needed more money and time than had initially been requested. (Designers of such projects often ask for less money than they need, in order to win initial approval.) “Frank Wolf was so strongly opposed to us,” Ochs said. “I was told that, after we were re-funded, someone said, ‘Frank, why were you giving us such a hard time?’ And he admitted that he was just trying to get the attention of Senator Mikulski.” Mikulski had also been a lead advocate in allocating funds for Hubble’s repair. (Wolf doesn’t remember the conversation.)
Not far from Ochs’s office, in a clean, high-ceilinged room, technicians were working on components while dressed in the sterile suits we once associated with Oompa Loompas and now associate with covid-19. Ochs said, of the J.W.S.T.’s frequent delays, “It’s my job to be straight up, not optimistic, not pessimistic.” Not long after we spoke, during an unfurling test of the sunshield at Northrop Grumman, its maker, it tore. In a subsequent “shake” test, twenty of a thousand screws that hold the sunshield cover in place came loose. Loose screws could lead to another tear. The screws were a consequence of a prior remedy: nuts had been added so that the screws wouldn’t protrude. But the nuts that solved that problem resulted in a handful of the screws not threading properly. The launch was pushed back again. Then, in two launches, Ariane 5 had a wonky separation of the payload-carrying part of the rocket from the main body. The J.W.S.T.’s launch is now expected to occur in late November.
Nikole Lewis, an astronomer at Cornell University and the deputy director of the Carl Sagan Institute, is an expert on exoplanets. She is also one of the lead scientists who will work with the telescope’s nirSpec (near-infrared spectrograph) instrument. On a sweaty day this spring, I spoke to her on the phone while my daughter played soccer with a mask on. “There had been no plans to look at exoplanets in the original design of J.W.S.T.,” she said. “That’s one benefit that has come from all the delays.” The nirSpec is a beautiful piece of engineering, designed to observe not only exoplanets but brown dwarfs and distant galaxies. For these objects, the nirSpec is equipped with thousands of microshutters, each tinier than a grain of sand. Close up, arrays of microshutters resemble graph paper, with each cell functioning as a lens cover that can be opened or closed. “It’s kind of as if it lets the instrument squint, to see something faint in the distance, without its light being drowned out by other, brighter objects,” Lewis told me. The instrument can observe a hundred different objects at once—each shutter has its own view—opening up more research opportunities for astronomers.
The “Spec” in nirSpec refers to spectroscopy, which is a way of analyzing what elements are present in a given object, based on the spectrum of light it emits. Lewis will use nirSpec to study the exoplanets around a star known as trappist-1. This star, a mere thirty-nine light-years away, has seven planets in its orbit. Three of them are “Goldilocks” planets—they appear to be the right temperature to possibly have liquid water on them. “Exoplanets used to be a very marginal field, which made it a great time to go into it,” Lewis said. “It was this niche thing.” The trappist-1 exoplanet system was discovered only in 2016, and Lewis has played a crucial role in exploring it, using Hubble.
“I just always loved planets,” Lewis said. “Like kids do.” Lewis grew up in Lafayette, Indiana. Her mother is a massage therapist, and her father is a UPS driver. Her mother had Lewis when she was seventeen, and Lewis’s grandmother had her mother when she was seventeen—a grandmother at thirty-four. “My grandmother was a very strong person, and she saw that passion in me for math and science, and she said, ‘How can we feed it?’ ” Her grandmother did math flash cards with her, and took her to museums and to symphonies. When Lewis was thirteen, her family sent her to space camp in Huntsville, Alabama.
“I was lucky, I came to the field of exoplanets in its infancy,” she said. “There wasn’t a lot of ego in the field. You weren’t going to win a Nobel Prize in exoplanets, like you would in cosmology. Though there was just a Nobel Prize given for exoplanet research a couple of years ago. I guess it’s changing.” The field tends to be populated with younger scientists, and many of the leaders are women. “I hope the field remains this place where there’s room for creativity,” Lewis said.
There will be no way to go out and fix the J.W.S.T. if anything goes wrong. It’s too far away. Although it’s difficult to imagine such a complex project succeeding, it’s also difficult to imagine that humans have flown a little helicopter on Mars, or that our cell phones speak to satellites in the sky, which then tell us where we are on the Brooklyn-Queens Expressway. If you were a sky-watcher in the past, you might have looked for the stars to tell you something about your love life, your luck, your finances, or whether or not you should invade Prussia. You might watch to know how to steer your ship, or when to plant your quinoa. What are we looking for now?
The seventeenth-century astronomer Johannes Kepler studied the physical world for the messages he felt that God had written into the Book of Nature. Galileo, in fact, had supporters inside and outside the Church. Sometimes people in power have been reluctant to acknowledge the truths that science uncovers. Each time we look farther, our universe gets larger. Or, depending on your perspective, we get smaller. Astronomers take the position—an incidentally ethical one—of being radically in favor of knowing.
Bob Williams, the former head of the Space Telescope Science Institute, grew up in a Baptist family in Southern California, one of five children. He’d wanted to be an astronomer since the seventh grade, when he received a pamphlet on astronomy in science class; he then saved his paper-route money to buy a telescope. He earned a scholarship to U.C. Berkeley and studied astronomy there. “My father didn’t want me to go to college,” he said. “He told me that if I went to get an education I would lose my faith. And he was right about that. We were raised to take every word in the Bible as literally true. But then I was learning about continental drift. About evolution.” Williams said that he is often asked about faith. Many traditions use the term “God” to mean, basically, everything that is. In that view, the universe itself is the Book, and astronomers are reading it as it is. ♦