Cosmic vision: What secrets NASA’s space telescope might reveal

It will travel 1 million miles into space – five times the distance to the moon – and then unfurl a kite-shaped sunshade the size of a tennis court. This umbrella will deflect the sun’s powerful rays, allowing the instrument to operate at a cryogenic minus 370 degrees Fahrenheit, cold enough to see infrared wavelengths without interference.

It will carefully unfold a set of 18 hexagonal mirrors made of beryllium, a rare metal known for its strength and ability to withstand extreme temperatures, which are coated in a veneer of gold. These will bloom into a flowerlike configuration stretching 21 feet across, making it the largest mirror ever deployed in space. 

It is this glistening marvel that scientists hope will usher in a new age of discovery about the cosmos. 

If all goes as planned, the $9.7 billion James Webb Space Telescope (JWST), scheduled to launch from French Guiana as early as Dec. 24, will provide humanity with the ability to peer farther into the heavens than ever before. The observatory could offer new insight into when stars first appeared, how galaxies evolved, and the nature of dark energy, as well as add knowledge to the question that most stirs the popular imagination – whether planets exist that can support life. 

The performance of the telescope may also go a long way toward determining the future of big astronomy projects. Webb has cast a long pall over the field after suffering from a seemingly endless set of cost overruns and schedule slips. It prevented time and money from being spent on other priorities.

“It’s hard to believe it’s really happening,” says Laura Kreidberg, a researcher at the Max Planck Institute for Astronomy in Germany, who will use the telescope to study the atmospheres of distant planets during its first year in space.

Astronomers are now looking ahead to determine how they will delve into the cosmic secrets of the future, including possibly sending aloft another giant observatory.

The negative experiences with JWST have already had at least one salutary effect: They have pushed scientists to offer more realistic financial estimates and timelines in their planning for upcoming projects and setting goals for space discovery. Further definition of and momentum for their plans, as well as the future of monumental science projects, will hinge on whether JWST can make it aloft safely – and what information it ultimately sends back to Earth.

Which is why astronomers are training their eyes so anxiously on a spaceport on the forested edge of South America, where a European Ariane 5 rocket will begin the observatory’s long journey toward the stars. 

With its sharp nose and triangular shape, the new observatory looks a little like a Star Destroyer from George Lucas’ imagination. You almost expect Darth Vader to emerge from behind the yellow beryllium mirror to fire off an ion cannon at unsuspecting rebels on the planet Hoth.

The telescope’s actual origins are far less Hollywood. The first glimmers of the instrument that would become JWST appeared in 1989, a year before the Hubble Space Telescope launched, when researchers began to picture the famous observatory’s successor. Astronomers wanting to capture light from the universe’s earliest stars and galaxies knew they needed a large instrument placed far from our planet, whose bright glow would cause interference. Initial estimates proposed a price tag of between $500 million and $1 billion, though there was skepticism that it could be accomplished for so little, with a targeted launch date of 2007. 

The telescope’s distance from Earth precluded the option of a repair mission, such as occurred with Hubble, meaning that the risk-averse engineers at NASA began rigorously testing every component during design and construction. As the project schedule lengthened, its science objectives expanded, especially as extrasolar planets became an increasing topic of interest in the field.

New instruments were added and anticipated costs went soaring. JWST eventually became one of the most expensive space projects in history, at nearly $10 billion. That figure doesn’t include the contributions from NASA’s two partners, the European Space Agency, which put up €700 million ($788 million) to launch the observatory and for instruments, and the Canadian Space Agency, which contributed $200 million (Canadian; U.S.$158 million) for sensors and other scientific tools.

After being labeled “the telescope that ate astronomy,” JWST survived a congressional cancellation attempt in 2011. NASA and private construction contractor Northrop Grumman put on a concerted effort to build public support and burnish its image. They even went so far as to display a full-size mock-up of the telescope at the 2017 Super Bowl in Houston, trying to turn a tortured science project into a rock star – the Bruce Springsteen of the cosmos. The ill-fated observatory’s problems continued the next year when it was discovered that screws and washers were falling off during vibration tests.

Yet backing from researchers has helped keep the project advancing through every delay and price increase. Scientists have stuck by the observatory because it will offer them exquisite and otherwise unobtainable views of the cosmos. For starters, its honeycomb mirror is nearly three times larger than Hubble’s and will have seven times the light-gathering power. And while Hubble sees in the same optical wavelength as our eyes as well as the ultraviolet portion of the electromagnetic spectrum, JWST’s instruments are geared toward the lower-frequency infrared. Because of the universe’s constant expansion, starlight emitted long ago has been stretched out toward such longer wavelengths.

Infrared light can also peer through obscuring dust. This means that only an infrared observatory can capture indispensable information about a long list of subjects – the origins of the first stars, the formation and development of galaxies, the compositions of both newborn and fully formed planets, and whether such planets contain the components necessary for life. Even as JWST helps solve some long-standing mysteries, it is sure to stumble across more.

“Anytime we have this new tool that allows us to get a different window onto our universe, we always seem to find something new and surprising,” says Lou Strolger, an astronomer at the Space Telescope Science Institute (STScI) in Baltimore.

Hubble helped uncover the existence of one such famous shocker, an unexpected and enigmatic substance known as dark energy, which is driving the cosmos to expand ever faster. Using information from dying stars observed with JWST, Dr. Strolger and his colleagues will be able to pin down the universe’s expansion rate with greater precision than ever before, potentially gleaning whether dark energy’s influence has changed during different epochs in our universe’s history. 

Given its long gaze, JWST is set to revolutionize our understanding of supermassive black holes in the early cosmos. Such beasts – often weighing millions or billions of times the sun’s mass – have been spotted lurking in the centers of just about every galaxy, though nobody knows how they came into being. One theory is that, in the distant past, clouds of hydrogen and helium grew so large that they collapsed under their own weight into the ultradense specks that are supermassive black holes.

“James Webb is actually going to be able to observe if this is the method,” says Allison Kirkpatrick, an astronomer at the University of Kansas in Lawrence.   

Supermassive black holes are thought to be potential anchors around which the first galaxies coalesced. Every time telescopes look further into the universe’s past, they see galaxies larger than should be possible, almost as if they snapped together in an inexplicably short timespan. JWST will give researchers unparalleled access to those ancient days, potentially explaining how such galaxies came about.

Because of conditions back then, the earliest stars were able to grow far bigger than their modern counterparts, becoming some of the most luminous stars that ever existed. Scientists suspect their glow was partially responsible for a process called re-ionization, when photons of light tore neutral atoms of hydrogen into their constituent protons and electrons. Most of the matter in the universe today remains in such a fractured form, and JWST might help astronomers determine what initially caused it.

The telescope’s infrared eyes will capture many details lurking inside the dusty cocoons where stars form today. Young stars tend to have disks of material around them, out of which spring planets. The specific molecules located at different places in these disks become the building blocks for such planets. JWST will give researchers the ability to identify where materials like water vapor can be found around sunlike stars, potentially explaining whether Earth formed in the presence of water or if the water was delivered later by asteroid and comet crashes.

“We’ve just never had this capability before,” says Alexandra Lockwood, communication lead for JWST, who studies protoplanetary disks at STScI.

Astronomers will also be able to scan fully formed planets and sniff their atmospheric compositions. Since every molecule leaves a characteristic signature in the light from such planets, researchers will be able to identify what gases are present. Hubble has done this for a handful of worlds and even detected water in their atmospheres, but simply knowing that the life-sustaining liquid is around isn’t enough to say whether a planet is habitable. Researchers need important contextual clues from chemicals such as carbon dioxide and methane, whose signals can only be seen in the infrared spectrum, to get a fuller view of distant places.

“For exoplanet atmospheres, JWST is an absolute game changer,” says Dr. Kreidberg of the Max Planck Institute.

Yet even an observatory as mighty as Webb will leave many questions unanswered. Scientists are already looking forward to their next heavenly facility, an infrared Hubble-sized instrument called the Nancy Grace Roman Space Telescope. It is slated to join JWST in its locale a million miles from Earth by 2027.

Proposed during the austerity measures of the early 2010s, Roman uses a secondhand mirror donated by the National Reconnaissance Office, an arm of the U.S. Department of Defense. It, too, has suffered from delays, cost overruns, and cancellation attempts. Though it will study the nature of dark energy and count exoplanets, the telescope will be blind to many wavelengths of light. 

In November, the National Academies of Sciences, Engineering, and Medicine released a long-awaited road map called the Decadal Survey on Astronomy and Astrophysics 2020 that outlines where the field should go next. Written by panels of experts, the report envisions the research topics of the future and endorses instruments that NASA and the National Science Foundation could build to study them. Its top-line recommendation for space-based observations is a telescope equal in size to JWST that would launch in the 2040s and cover the ultraviolet, optical, and near-infrared portions of the electromagnetic spectrum, allowing it to directly address two-thirds of the survey’s open science questions. 

“The report is bold, visionary, and extremely thoughtful,” says Ken Sembach, STScI’s director who conducts science and flight operations for JWST. “It’s crafted in a way that brings the whole community along.”

JWST’s fingerprints can be found all over the Decadal, both in the research topics it is expected to push forward and in the proposals it makes regarding this future facility. The survey estimates the prospective telescope to cost around $11 billion – roughly the inflation-adjusted price of both JWST and Hubble. It recommends the field establish a Great Observatories Mission and Technology Maturation Program that would invest money in developing the necessary cutting-edge equipment for such an instrument, with regular check-ins to make sure the project still makes sense.

“The history of JWST – obviously everybody in the room has to find their response to it,” says Bruce Macintosh, an astronomer at Stanford University in California who was a member of the Decadal’s steering committee. “The response could have been, ‘We don’t know how to do big missions.’ And I’m proud that instead the response was, ‘What can we do to do a big mission without that happening again.’” 

Many see the report as indicating that astronomers have learned at least some lessons from their past experiences. “The Decadal is making you offer real estimates of your telescopes,” says Dr. Kirkpatrick at the University of Kansas. “When James Webb was proposed, they weren’t as strict about that, and so the plan was basically just to lie. The Decadal has stopped that nonsense.”

Yet it remains to be seen if the field can get itself out of what feels like a repeated cycle of delays and overruns that have hampered telescopes as far back as Hubble. Many are hopeful that Decadal’s recommendations will at least be a step toward avoiding future problems of this kind.

“I think the bottom line is that it’s saying, ‘It’s too hard to get locked into a particular brand,’” says Dr. Strolger of STScI. “Let’s think more about the science you want to achieve and the technology you need to get there.”

Once JWST is launched and new discoveries are regularly flowing in, researchers should be emboldened about moving ahead. Perhaps it makes sense that the field, which investigates some of the grandest and most sublime mysteries in existence, continually makes such audacious proposals in order to push itself forward.

“I think one of things about astronomy is that we think big,” says Dr. Lockwood at STScI. “If we always thought safe, we wouldn’t get the discoveries that inspire the public.”