Last Christmas, NASA gave astronomers and humanity a gift with the launch of the James Webb Space Telescope (JWST), a gift that kept on giving all year long. The space agency’s largest and most powerful observatory has glimpsed both the most distant views of the early universe and close-up views of a spacecraft deflecting an asteroid just 6.8 million miles from Earth. And this only in its first months.
“It’s very fair to say that the telescope has exceeded expectations,” said James Webb Space Telescope project scientist Klaus Pontoppidan of the Space Telescope Science Institute in Baltimore. “Overall, we’re doing better than the requirements. It’s sharper images, we can see deeper. And it’s really made a difference.”
A massive international effort made in collaboration with the European and Canadian space agencies, the telescope required the work of 20,000 people over 20 years to build. It was launched on an Ariane 5 rocket that put it into orbit so perfectly that the maneuvering fuel saved aboard the spacecraft will extend its life to about 25 years, instead of 10, according to program scientist Eric Smith Webb at NASA headquarters.
By almost every measure, JWST’s performance is better than expected, he said: “The lifetime is more than twice as expected. The vision is twice as sharp. It will be 25 to 30 percent more sensitive, so we can see fainter or improve a certain level of exposure. It’s more stable, about seven times more stable than we thought.” This means astronomers wait less time to capture data after aiming the telescope, making their operations more efficient.
“You just move it and ‘boom,’ you’re ready to go right away,” Smith said. “This also makes us feel better about future telescopes.”
In its first six months of operation, the only bumps in the road for JWST have come from micrometeorite impacts. The space telescope, its 18 mirrors deployed to measure more than 21 feet across, orbits the sun about 1.5 million miles from Earth in a stable gravitational spot considered pristine compared to the orbit each time most littered around the Earth. But a large strike of micrometeorites in May convinced engineers to move the observatory away from the direction of its orbital motion, a proposal to minimize impacts from fast-moving space dust hitting its mirrors head-on. “Just like you don’t stick your face out the car window when it’s moving,” Smith said.
Launching on Christmas Day 2021, the $11 billion space telescope overcame years of delays and cost overruns to deploy those mirrors perfectly in a 178-step origami exercise in space, before revealing its first images in July. A parade of discoveries has followed. Here are some of the highlights.
Deep field
NASA’s James Webb Space Telescope has delivered the deepest and sharpest infrared image of the distant universe yet. (Space Telescope Science Institute Office of Public Outreach/NASA, ESA, CSA, STScI, Webb ERO)
Early on, JWST showed off its power, roughly 100 times stronger than the Hubble Space Telescope, with its own “deep-field” image of distant galaxies, the islands of stars that fill space like our Way Milky Way, to compare them with those of its historical predecessor, the Hubble Space Telescope. The further the telescope can see, the further back in time it looks, because the speed of light, although very fast, is limited. That’s why the JWST deep field contains galaxies dating only a few hundred million years after the Big Bang (which happened about 13.8 billion years ago) among the faintest in the picture. The view focuses on a nearby massive galaxy cluster, whose gravity bends the light of more distant galaxies, stretching them into distorted, elongated dimensions. However, this image spans a swath of deep space equivalent to just a patch of sand rising skyward.
Hubble has produced a series of increasingly deeper deep-field images over the past three decades, only to be surpassed, as intended, by JWST. The “gravitational lensing” of light from these more distant, distorted galaxies magnifies the light from stars of older ages even further than a normal view of the sky would allow, an optical effect predicted by Albert Einstein. So you can expect to see more deep-field images in the coming years as JWST operators refine spacecraft control and take advantage of future gravitational lensing opportunities.
Burning hourglass
The dark cloud protostar L1527, shown in this image from NASA’s James Webb Space Telescope’s Near-Infrared Camera, is embedded within a cloud of material that fuels its growth. (J. DePasquale, A. Pagan and A. Koekemoer (STScI)/NASA, ESA, CSA and STScI)
Unlike Hubble, JWST operates in the infrared spectrum, which allows it to peer through the clouds of dust and gas that hide the inner workings of stars. A beautiful example was the “burning hourglass” of the young “protostar” L1527, only 10,000 years old. A nascent solar system can be seen being born next to it cutting a line through the center of the infant star, which can only be seen as a dark cloud in other wavelengths of light, such as the visible spectrum seen by Hubble.
Our own solar system was born in a similar conflagration roughly 4.6 billion years ago, said Pontoppidan, who called the hourglass an early favorite. The image adds to observations that suggest planets form very early in the lives of stars, something that was uncertain just a few decades ago. “Each telescope is in a way a time machine. It’s not as if we’re watching our own solar system being born, but here we’re seeing a very similar one in its first moments.”
Early galaxies
Two of the most distant galaxies ever seen are captured in these Webb Space Telescope images of the outer regions of the giant galaxy cluster Abell 2744. (Zolt G. Levay (STScI)/NASA, ESA, CSA, Tommaso Treu (UCLA) )
One of the main missions of the JWST is to investigate the era of the first stars, those that were born shortly after the origin of the universe. And in its first months, the first observations of the era have served as puzzles. The first JWST observations of galaxies existing between 350 and 450 million years after the origin of the universe found them to be bigger and brighter than expected, as well as easier to find. “It’s like we walked into the kindergarten and we saw little kids. So it’s like, ‘What’s going on here?'” Pontoppidan said. “There doesn’t seem to be any explanation for it right now.”
For the first galaxies to be so bright, they must have been born only 100 million years or so after the afterglow of the Big Bang faded, in a “dark age” when the universe was filled with clouds of hydrogen gas. “This is probably the most exciting science from the telescope to date,” he added. “It’s not something you can see directly in a picture, it’s something that requires careful analysis, but I’m certainly, and this isn’t even my own area of science, I’ve been amazed at the incredible power we have to see the most distant galaxies in the universe.”
Pillars of creation
NASA’s James Webb Space Telescope’s mid-infrared view of the Pillars of Creation strikes a chilling tone. The thousands of stars in this region seem to disappear, as stars normally don’t emit much mid-infrared light and the seemingly endless layers of gas and dust become the centerpiece. (Joseph DePasquale (STScI), Alyssa Pagan (STScI)/NASA, ESA, CSA, STScI)
The stunning images don’t come much more impressive than the JWST view of the “Pillars of Creation” released in October, a dust-covered view set in the Eagle Nebula, a stellar nursery some 6,500 light-years from the earth. (A light-year is about 5.9 trillion miles.) First observed by Hubble in 1995, the new image shows the power of a “mid-infrared” instrument aboard JWST, which takes exquisite images of the light in the middle of the infrared spectrum. as the name suggests. Inside the dusty swirls of the pillars, news stars are merging, some of them visible in earlier Hubble images taken in visible light. “In astronomy, you have to look at many kinds of light,” Pontoppidan said. “Nature is not nice to us. It does not provide all the information about a certain process of physical object or planet or anything in a good area of the electromagnetic spectrum. We need all kinds of wavelengths,” which is why JWST is meant to work in conjunction with other observatories run by NASA and the European Space Agency.
The JWST instrument that took the image of Pillars, the Mid-Infrared Instrument (MIRI), is pretty much the only one that has given operators problems, leaving it partially offline until November and slowing the pace of their operations. The problem slowed some investigations of planets just forming in young solar systems, which will likely be in the news next year from JWST.
Exoplanet atmosphere
The atmospheric composition of the hot gas giant exoplanet WASP-39 b has been revealed by NASA’s James Webb Space Telescope. This graph shows four transmission spectra from three of Webb’s instruments operated in four instrument modes. Top left, NIRISS data show fingerprints of potassium (K), water (H2O), and carbon monoxide (CO). At top right, the NIRCam data shows a prominent water signature. In the lower left, the NIRSpec data indicate water, sulfur dioxide (SO2), carbon dioxide (CO2), and carbon monoxide (CO). At bottom right, additional NIRSpec data reveals all these molecules, as well as sodium (Na). (NASA, ESA, CSA, J. Olmsted (STScI))
Not so much an impressive image as an impressive measurement, JWST reported in August a first detection of atmospheric chemistry on a world orbiting another star. The light spectra of Wasp-39b, a jumbo-sized “hot Jupiter” planet closely circling its host star, reveal its chemical…