Lisa Dang wasn’t even born when astronomers started planning the most ambitious and complex space observatory ever built. Now, three decades later, NASA’south James Webb Space Telescope (JWST) is finally most to launch, and Dang has scored some of its beginning observing time — in a research surface area that didn’t even exist when it was existence designed.

Dang, an astrophysicist and graduate student at McGill University in Montreal, Canada, will be using the telescope, known as Webb for curt, to stare at a planet beyond the Solar System. Chosen K2-141b, information technology is a world so hot that its surface is partly molten rock. She is one of dozens of astronomers who learnt in March that they had won observing time on the telescope. The long-awaited Webb — a partnership involving NASA, the European Space Bureau (ESA) and the Canadian Space Agency (CSA) — is slated to lift off from a launch pad in Kourou, French Guiana, no earlier than 22 Dec.

If everything goes to plan, Webb volition remake astronomy past peering at cosmic phenomena such equally the most afar galaxies e’er seen, the atmospheres of far-off planets and the hearts of star-forming regions swaddled in dust. Roughly 100 times more than powerful than its predecessor, the Hubble Space Telescope, which has transformed our agreement of the cosmos over the past 31 years, Webb will reveal previously hidden aspects of the Universe.

The Webb telescope will spend hundreds of hours surveying this patch of sky, seen here in an epitome from the Hubble Space Telescope that captures 7,500 galaxies, some more 13 billion years old.
Credit: NASA, ESA, Rogier Windhorst (ASU), S. Cohen (ASU), K. Mechtley (ASU), 1000. Rutkowski (ASU), Robert O’Connell (UVA), P. McCarthy (OCIW), N. Hathi (UC Riverside), R. Ryan (UC Davis), Haojing Yan (OSU), Anton M. Koekemoer (STScI)

“Webb has such transformative capabilities that — to me — it’south going to be the ‘before’ times and the ‘after’ times,” says Jane Rigby, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who serves as Webb’due south operations projection scientist.

Just if anything goes incorrect, it will exist an ignominious setback to what is already the most expensive astronomical gamble in history. The telescope took decades and more than US$x billion to develop, and frequent delays repeatedly ate into NASA’s astrophysics upkeep. But this yr, the telescope has been enveloped in controversy over whether it ought to remain named afterwards James Webb, who headed NASA in the 1960s when a NASA employee was fired on suspicion of beingness gay. Webb also held a high-ranking position in the US Department of State in the belatedly 1940s and early 1950s, at a fourth dimension when that department was systematically rooting out and firing gay and lesbian people because of their sexual orientation.

When the telescope lifts off subsequently so many delays and then much argue, it will carry with information technology the hopes of thousands of astronomers effectually the world. “In that location aren’t many times in your life when you’re on the cusp of such a big affair,” says Heidi Hammel, an astronomer and vice-president for scientific discipline at the Association of Universities for Research in Astronomy in Washington DC, who has worked on Webb for decades. “In that location are a lot of emotions.”

Decades of development

The first glimmers of what would go Webb arose at a workshop at the Space Telescope Science Found in Baltimore, Maryland, in 1989. Information technology was the yr before the launch of the Hubble Space Telescope, and scientists were already thinking about how to follow up that transformative observatory. What ultimately emerged were plans for a space telescope with a 6.five-metre-wide primary mirror, about three times the size of Hubble’southward, and made up of 18 hexagonal segments. The mirror is so large that information technology must be folded up like origami during launch and unfurled once in space. Shading it will be a kite-shaped sunshield the size of a tennis court, made of 5 aluminium-coated layers that block the Sun’s estrus and keep the telescope cool enough to operate.

Webb’s overall cost was originally estimated at $one billion — an appraisal few believed fifty-fifty then — and has since ballooned. NASA provided US$ix.vii billion, including funds to comprehend operating costs in space; €700 million (US$810 million) came from ESA; and the CSA contributed Can$200 million (US$160 million). The project’s skyrocketing costs drew intense scrutiny from government auditors as well as perennial questions as to whether information technology would be worth its unprecedented price tag. “To exist truly transformational in a field, you have to build the tool you demand,” says Hammel. “This is what it costs to practice this.”

Plagued by repeated cancellations and blueprint changes, the telescope finally took shape in laboratories around the earth and was then assembled at Goddard. It was afterward combined with the rest of the observatory at Northrop Grumman Aerospace Systems in Redondo Beach, California. There, Webb ran into even more problem when technicians damaged it by using the incorrect solvent to make clean propulsion valves. After, screws literally came loose during testing.

Now, 32 years after its formulation, Webb is finally sitting at the spaceport in Kourou in training for launch. It is destined for a point in space ane.5 meg kilometres from World — also far away for astronauts to visit and gear up the telescope if something goes wrong. Hubble required an afterward-launch repair in 1993, when astronauts used the space shuttle to get to the Earth-orbiting observatory and install cosmetic optics for its principal mirror, which had been improperly ground.

If it launches successfully, Webb will probe the cosmos in the about- to mid-infrared wavelengths, near of which are longer than Hubble tin run across. That means Webb can study light that has travelled from faraway galaxies and been stretched to redder wavelengths by the expansion of the Universe. Webb will also be able to study grit that enshrouds star-forming regions besides as the gas between the stars, both of which are non as visible at shorter wavelengths. Like Hubble, it volition exist able to accept spectra of astronomical objects, significant it tin can split their light into components to determine what they are made of.

World’south atmosphere interferes with well-nigh ground-based infrared astronomical studies. Space-based telescopes, such as ESA’south Herschel Space Observatory, which operated between 2009 and 2013, have explored the Universe in infrared light before. But Webb’s enormous mirror and suite of sensitive instruments (run into ‘New eye in the sky’) mean that its discoveries volition surpass those of any previous infrared infinite telescope, scientists say. “It’due south going to change a lot of what nosotros know about a lot of areas of astronomy,” says Jeyhan Kartaltepe, an astronomer at the Rochester Institute of Technology in New York.

New eye in the sky: Infographic that shows the Webb telescope and it's sunshield, and it's orbital location in relation to Earth

Graphic: Nik Spencer/Nature; ‘Common cold telescope’ main image: NASA GSFC/CIL/Adriana Manrique Gutierrez

Because it can spot faint red objects, Webb is primed to observe some of the first stars and galaxies to class after the Large Blindside created the Universe 13.viii billion years ago. Webb will almost certainly shatter the record for the most afar galaxy ever observed, which is currently held by an unassuming galaxy named GN-z11 that lies xiii.4 billion light years from Earth1

I large written report volition look at a region of sky that is the size of 3 total Moons, aiming to capture one-half a million galaxies in it. This survey, known as COSMOS-Webb, builds on an ongoing projection that has used almost every major ground- and space-based telescope to study the aforementioned patch of sky, which lies forth the angelic equator and tin be seen from both the Northern and Southern hemispheres. Webb volition look at this field for more 200 hours, making it the biggest project for the observatory’southward outset year of science and creating a rich data set for astronomers to mine for discoveries. Webb’s infrared view will probe, for instance, the period from around 400,000 years to 1 billion years after the Big Bang, when the first stars and galaxies lit up the Universe. This epoch, known as the cosmic reionization era, set the stage for today’due south galaxies to evolve. “There’s a lot we don’t know nigh that time flow,” says Kartaltepe, who co-leads Creation-Webb.

By observing these extremely distant astronomical objects, scientists tin answer questions such as how the beginning stars assembled into galaxies and how those galaxies evolved over time. Getting a ameliorate film of galaxy formation in the early Universe will help astronomers to sympathize how the modern cosmos came to be.
 Mariska Kriek, an astronomer at Leiden Observatory in the Netherlands, plans to utilise Webb to study distant galaxies that are no longer forming stars. The observations volition reveal the chemic composition of stars in those galaxies and the velocities at which they are moving. Those data, in turn, will help Kriek to unravel the mystery of how and why these galaxies stopped forming stars at some signal in their history, different galaxies that did not ceaseiii. “Nosotros’re looking for a very, very faint indicate,” she says. “This is really what James Webb is going to open up.”

Science centre: infographic that shows a side view of the Webb telescope and the size of its mirror compared to Hubble's.

Graphic: Nik Spencer/Nature

Peering at distant planets

When not looking at stars and galaxies, Webb will spend a lot of its time scrutinizing planets, specially some of the thousands that have been discovered across the Solar System. It can picket as a planet slips beyond the face of a star and the star’s lite briefly shines through the planet’s atmosphere. Webb’s spectral assay can reveal the limerick of planetary atmospheres in greater detail than ever before — and astronomers are especially keen to find molecules such as methyl hydride and water, which signal weather condition that could support life. In its first year, Webb volition study some of the most famous exoplanets, including the seven Earth-sized worlds that orbit the star TRAPPIST-ane.

Dang volition observe several exoplanets using Webb, just the project she is leading will explore the globe K2-141b, which is just ane.5 times the size of Earth and travels so close to its star that part of information technology is molten. Information technology is an example of a rare ‘lava planet’ with a geology unlike anything known in the Solar System. Webb’south infrared vision might detect minerals in K2-141b’s atmosphere that take been vaporized off its surface, and the observatory might even map temperatures beyond the planet. “Webb is opening a lot of avenues for exoplanet science that didn’t exist before,” says Dang.

The repeated delays in developing and building Webb actually worked to the benefit of exoplanet scientists, says Néstor Espinoza, an astronomer at the Space Telescope Scientific discipline Institute. At one point, Webb was scheduled to launch in 2011, simply astronomers didn’t confirm the first atmosphere around an exoplanet until 20054
five. Webb’s delays gave them more time to tweak its instruments to suit the written report of exoplanet atmospheres. “We are much better poised now than if JWST were launched in 2011,” says Espinoza.

Origin stories: infographic that shows a cosmic timeline and how far back in time Webb will be able to see..

Graphic: Nik Spencer/Nature

Webb will target a wide range of exoplanets, including gas giants and the class of planets that are larger than Earth but smaller than Neptune, which are the most common type of exoplanet discovered then far.

Closer to domicile, Webb volition accept enough of objects to expect at. Astronomers hope to use its broad range of wavelengths to reveal previously unseen details of the Solar Organization’s residents. The color and surface chemistry of the icy worlds in orbits virtually Pluto and beyond, for instance, could help to reveal secrets of the Solar System’s origins. Hammel and others plan to apply the telescope to study the upper atmospheres of the ice giants Neptune and Uranus, the chemical make-ups of which are best seen in the infrared. By linking studies of the upper atmosphere with those of the lower atmosphere, seen at other wavelengths by other telescopes, scientists can obtain a 3D picture of how a planet’s atmosphere behaves. This, in turn, can illuminate the workings of similar behemothic planets beyond the Solar Arrangement.

Last hurdles

Although some scientists see benefits in the delays, many more take criticized NASA and its contractors over the years for the numerous issues in developing Webb. The telescope was strongly endorsed in a 2001 report setting out a route map for US astronomy, but NASA struggled, specially betwixt 2002 and 2008, to develop the many technologies required for such a circuitous observatory, such equally the sunshield. A scathing report from an independent review in 2010 noted that key problems stemmed from NASA underestimating the fourth dimension and money required: “This resulted in a projection that was just not executable inside the approaching resource,” information technology concluded.

NASA restructured the direction of the project in response, but in 2018, another contained review over again slammed the bureau for insufficient oversight. Costs were forecast to rising by another $800 million, and the launch was delayed by almost a year — and was so further held up because of problems at Northrop Grumman and challenges stemming from the COVID-19 pandemic. Earlier this year, the controversy over the telescope’s naming broke out; NASA announced in Oct that it had no plans to change the name, following a historical investigation into James Webb’s actions. Many astronomers, however, have expressed unhappiness with the limited information that NASA has released nigh the telescopic of that investigation.

And then, less than a month before a scheduled launch date of 18 December, Webb hit yet another hurdle. At the facility in Kourou, a ring that clamped the telescope to the launch vehicle released unexpectedly, causing vibrations. NASA investigated and concluded that the vibration did not cause any damage.

In the red: infographic that shows the ranges in the infrared spectrum in which Webb's instruments operate, with simulated data.

Graphic: Nik Spencer/Nature; Infrared simulations: Madeline Marshall (Univ. Melbourne)

If and when Webb finally lifts off, which is always a risky procedure, the telescope faces a carefully choreographed six-calendar month sequence of events that starts with unfolding and deploying the sunshield, then unfolding and deploying the master and secondary mirrors. The telescope will begin cooling downward every bit it travels towards its final orbit around the gravitationally stable betoken in space known as L2, or the second Lagrange point. At this location, Webb will always be pointed abroad from the Dominicus with World at its back, allowing it to see distant objects while the sunshield keeps it cool.

Then come two months of synchronizing and aligning the mirrors and telescope eyes, and a month of calibrating the instruments. By June 2022, if all goes well, Webb will finally exist ready for science.

Astronomers take planned the next steps carefully. “We have to hit the ground running and work very quickly,” says Kartaltepe. Start will come up a gear up of ‘early release’ observations. Their contents are closely guarded but will probably involve a series of jaw-dropping images chosen to testify off the telescope’s capabilities. After that will come a series of general observations, the data from which NASA will release immediately to the astronomical community. I such project will look at infrared galaxies that formed as a result of violent galactic collisions. “We are the outset guinea pigs to see what data will come off JWST and how we will analyse that data,” says Vivian U, an astronomer at the University of California, Irvine, who works on the project. “I know I’k continuing on the shoulders of giants.”

Astronomers who spent years working to build Webb’due south instruments take been guaranteed observing time, as have six scientists, including Hammel, who are tasked with pursuing research of interdisciplinary interest. Afterward that come the proposals led by principal investigators. Astronomers in Europe will get at least fifteen%of the observing fourth dimension, and ones in Canada will have at least 5%, for their space agencies’ contributions to Webb. Proposals are assessed using dual-anonymous peer review, in which reviewers and proposers exercise not know each other’s names — a practice that has been shown to reduce gender bias in allocating telescope time6.

Webb is expected to operate for at least 5 years and mayhap upwardly to 10, a lifetime dictated by the amount of fuel that information technology uses to orient itself in space. In the concurrently, the ageing Hubble continues to limp along. Information technology was last upgraded by astronauts in 2009, and has been slowly degrading since then. A computer failure knocked it offline in June, and engineers had to switch to a back-up system before getting it working once more in July. Hubble’s science instruments besides went offline in Oct attributable to internal communications problems. Engineers restored all of the instruments to performance in early December.

Later on many years of waiting, astronomers are more than than set up for Webb to option up the baton of discovery from Hubble. “I’m probably almost excited for the things we don’t know still,” says Kriek.