Science is such a forward-looking endeavor that it’s all the more rewarding when long, challenging efforts finally come to fruition. And 2022 was a year with many payoffs, as researchers began unlocking the secrets of our solar system’s asteroids and received rich maps of the stars that populate the Milky Way.
Excitement reigned as we moved an asteroid from 6.8 million miles (11 million kilometers) away. New and intriguing phenomena popped onto the scene, proving we still have much to understand about our universe. And two groundbreaking stories stole headlines, as we finally glimpsed the monster black hole at the heart of our galaxy and received the first stunningly sharp images from humanity’s most challenging and risky space telescope effort to date.
It was also a year for reflection, as landmark missions drew to a close. Yet even as opportunities end, others are waiting around the corner, and astronomers are always ready to seize them.
10. Astronomers release 10-year wish lists
Every 10 years, an expert panel of astronomers considers how missions are performing, where changes can be made, and what cosmic questions astronomy should focus on for the next decade. Their findings are called the decadal survey. Although not a strict rulebook, the survey is considered by agencies such as NASA when choosing how to spend limited budgets.
Delayed a year by the COVID-19 pandemic, the National Academies of Sciences, Engineering, and Medicine released Pathways to Discovery in Astronomy and Astrophysics for the 2020s, also called Astro2020, on Nov. 4, 2021. Its 615 pages outline top pursuits in observational and theoretical astronomy, broken into three main focuses. They are: exoplanets and stars, including finding and characterizing Earth-like worlds; formation and evolution of stars and galaxies, particularly how they are intertwined; and multi-messenger astronomy, which combines observations across the electromagnetic spectrum.
One major recommendation is the creation of the Great Observatories Mission and Technology Maturation Program to focus on the development of an $11-billion 6-meter combination infrared/optical/ultraviolet space telescope and, later in the decade, additional $3-billion and $5-billion missions to study the far-infrared and X-ray regimes, respectively. The committee also suggests investing in the Giant Magellan Telescope and Thirty Meter Telescope, the CMB Stage 4 observatory to study signals left by the Big Bang, and the Next Generation Very Large Array radio facility.
On April 19, 2022, the equivalent report for the planetary science community, Origins, Worlds, and Life: A Decadal Strategy for Planetary Science and Astrobiology 2023-2032, was released. It endorses NASA’s Mars sample-return mission and the Endurance-A rover, which will cache material from the lunar south pole for astronauts to retrieve. The report also recommends funding development of a mission to fly past a near-Earth object to help us better prepare for impact threats. Over the longer term, the committee supports missions to comets, asteroids, and moons. Large-scale undertakings prioritized by the report include the Uranus Orbiter and Probe and the Enceladus Orbilander.
The survey also includes the first “state of the profession,” discussing diversity and equity in planetary science and astrobiology. While acknowledging progress in these areas, “much work remains to be done, in particular to address persistent and troubling issues of basic representation by race/ethnicity.”
Recommendations in hand, it is now time for funding agencies to decide where and how to allocate resources in the coming years.
9. First results are rolling in from Ryugu
In 2019, the Japan Aerospace Exploration Agency’s Hayabusa2 collected a total of 0.19 ounce (5.4 grams) of material from both the surface and subsurface of the near-Earth asteroid 162173 Ryugu. The craft delivered its samples to Earth Dec. 6, 2020, via a re-entry capsule dropped off as Hayabusa2 zipped past.
Starting in late 2021, the results of researchers’ initial analyses began to appear. Ryugu is a carbonaceous or C-type asteroid, rich in both water and organic (i.e., carbon-based) material. Early studies found that Ryugu’s particles have been heavily altered by water. Their low density has led researchers to surmise that the boulders covering much of the surface are highly porous.
“Ryugu samples are the most chemically pristine materials ever analyzed in the lab,” says Ann Nguyen, a planetary scientist in the Astromaterials Research and Exploration Science Division at NASA’s Johnson Space Center. Their composition closely matches that of CI chondrite meteorites, which have been long considered representative of the material that formed the Sun and solar system.
“Ryugu likely came from a larger precursor asteroid that was several tens of kilometers in size,” Nguyen adds, which studies have determined “formed beyond Jupiter, and beyond Ryugu’s current orbit.” One study, led by former graduate student Kaitlyn McCain and postdoc Nozomi Matsuda, working with Kevin McKeegan at the University of California, Los Angeles, discovered hints that its parent formed quickly in the early stages of our solar system’s assembly. “It’s really hard to know when the asteroids were put together,” McKeegan says. “This has implications for models about how things would accrete in the early solar system.”
Another study, published June 10 in the Proceedings of the Japan Academy by a team at Okayama University in Japan, found features of interstellar material predating our solar nebula, as well as amino acids within Ryugu’s organic material. Those authors suggest Ryugu’s parent may have been a comet whose composition was altered as passes through the inner solar system boiled away its ices, leaving behind a porous, rocky body.
“This mission was really, to my mind, fantastically successful,” McKeegan says. One thing is clear: Ryugu has much to teach us about its past.
8. Gaia Release 3 offers a data deluge
The European Space Agency’s Gaia satellite has the ambitious goal of surveying billions of Milky Way stars to build a three-dimensional map of our galaxy. Every few years, the team puts out a data release, or catalog of measurements; the first was in 2016 and the second in 2018. Following a preliminary early third data release in late 2020, astronomers were eagerly awaiting the complete Gaia Data Release 3 (DR3) from the mission.
Finally, on June 13, 2022, ESA published the full DR3. Among its contents are the classifications, temperatures, and distances for nearly 1.6 billion objects; the 3D motions of 33 million stars; a 3-million-pixel map of galactic dust; observations of more than 10 million variable stars, eclipsing binary systems, transiting exoplanets, and supermassive black holes; and measurements of some 158,000 solar system objects, such as asteroids and moons. And there’s much more.
Alongside the release came stunning maps showing how stars orbit and move within the Milky Way, and their chemical composition. These new details allow researchers a better-than-ever look at how, where, and when the stars in our galaxy were born, based on the elements they contain and their motions through space.
The team also discovered that Gaia can detect a particular kind of starquake, which ripples through the star and distorts its normally spherical shape. Many were seen in stars not expected to show them, and astronomers are eager to decipher the strange behavior.
DR3 has already triggered a slew of papers on topics ranging from our solar system to far-flung galaxies, as well as a dedicated special issue of Astronomy & Astrophysics detailing the data and their potential. And there will be many more to come, as researchers get the chance to really dig in.
7. Researchers (possibly) find a rogue black hole
Astronomers have mapped numerous black holes throughout our galaxy — all in binary systems, visible only through interactions with a neighbor. Lone, quiet black holes are hard to find.
That changed Jan. 31, when a paper uploaded to the arXiv preprint server reported a black hole wandering solo. The path to this detection began in 2011, when a massive, dark object passed between Earth and a star near the Milky Way’s bulge. For 270 days, the star brightened as its light was bent and focused by the mass of the intervening object — a process called gravitational microlensing. This piqued the interest of researchers hunting for free-floating, or rogue, black holes. Astronomers think there may be hundreds of millions such objects in the Milky Way; although they give off no light, they could be found through microlensing.
Heavier objects cause longer microlensing events. But duration alone is not enough to definitively weigh the intervening object. So, researchers used the Hubble Space Telescope to precisely measure the star’s apparent position for six years. The amount it seemed to shift in the sky gave a much more robust solution for the lens’ mass. Their conclusion: The interloper is a black hole between 5.8 and 8.4 solar masses. “The object we detected is so massive that if it were a star, it would be shining brightly; yet we detected no light from it,” says study leader Kailash Sahu of the Space Telescope Science Institute in Baltimore. Sahu’s team published their results July 6 in The Astrophysical Journal.
But a separate team led by Casey Lam and Jessica Lu of the University of California, Berkeley, also studied the event. Their analysis of the Hubble data, published the same day in The Astrophysical Journal Letters, found the lens is between 1.6 and 4.4 solar masses. Anything so dark above 2.2 solar masses can only be a black hole, but a lighter object in this range is more likely a neutron star. “As much as we would like to say it is definitively a black hole, we must report all allowed solutions. This includes both lower-mass black holes and possibly even a neutron star,” Lu said in a press release.
The teams hope further observations of the background star — whose position is still offset slightly — taken in fall 2022 will soon distinguish between models, putting the mystery to rest.
Getting Artemis off the ground
On Aug. 29, 2022, NASA’s massive Space Launch System (SLS) rocket, topped with an uncrewed Orion capsule and an additional payload of 10 tiny CubeSats, sat ready to launch Artemis I — the first step in the next era of U.S. lunar exploration — from Cape Canaveral, Florida. The mission’s goal was simple: Send Orion around the Moon and back over the course of about two weeks, releasing the satellites along the way to complete their own lunar science missions.
But 40 minutes before liftoff, the launch was held … and then scrubbed. Officials discussed several reasons for the halt, including a leak in a liquid hydrogen fueling line and, more concerning, the failure of one of SLS’s RS-25 core stage engines to reach the proper temperature during pre-launch cooling. Ultimately, engineers ran out of time to troubleshoot as the two-hour-long launch window closed.
NASA next set Sept. 3 for launch, but again during fueling, the rocket experienced a recurring liquid hydrogen leak and the attempt was scrubbed. After replacing multiple seals and carefully checking the rocket, a new launch date of Sept. 27 was announced.
The weather had other ideas. On Sept. 24, NASA preemptively delayed the launch as officials worriedly watched the tropical storm that would shortly become Hurricane Ian barrel toward the state. Two days later, NASA announced it would roll SLS and its payload the 4 miles (6.4 km) back into the protective shelter of the Vehicle Assembly Building ahead of the storm.
After Ian, NASA targeted a Nov. 14 launch, rolling the rocket back out to the pad. But by the 8th, the agency deferred to Nov. 16 as Tropical Storm Nicole intensified.
Finally, at 1:47 A.M. EST on Nov. 16, Artemis I leaped off the launchpad and into history, kicking off its 25.5-day mission.
6. Exoplanets near and far
2022 was another banner year for exoplanets. On Feb. 10, astronomers reported a third possible planet around our nearest stellar neighbor, Proxima Centauri, just 4 light-years away. Called Proxima d, it joins the Earth-mass world Proxima b, spotted in August 2016; and Proxima c, a super-Earth reported in January 2020.
Based on observations from the European Southern Observatory’s Very Large Telescope in Chile, Proxima d is just one-quarter the mass of Earth. It orbits once every five days some 2.7 million miles (4.3 million km) from its star — less than one-tenth Mercury’s distance from the Sun. Because Proxima Centauri is only 12 percent the Sun’s mass and 14 percent its diameter, Proxima d (like Proxima b, but not c) lies in its habitable zone, where conditions could support surface water.
For now, Proxima d and c remain planetary candidates awaiting confirmation with follow-up observations. While many candidates are ultimately confirmed as planets, some are instead found to be starspots, noise in the data, or even brown dwarf companions. But if confirmed, they’ll be in good company: Just a month after Proxima d’s discovery was published, NASA announced March 21 that the astronomical community had confirmed a total of 5,000 extrasolar planets. That’s a huge accomplishment for a field born roughly 30 years ago.
Now, researchers are excited to make the switch from simply racking up increasing numbers of planets to exploring their properties, including habitability. In particular, new tools such as the recently launched James Webb Space Telescope and ESA’s upcoming Ariel satellite will give us a closer look than ever before at the atmospheres of the worlds circling the myriad stars of our Milky Way.
5. A ‘teenage’ pulsar bursts onto the scene
When a massive star dies, it goes out with a bang, sometimes leaving behind a rapidly spinning neutron star, known as a pulsar. These throw off high-speed winds of particles that move outward to form a bubble in their surroundings, called a pulsar wind nebula. There’s one at the heart of the Crab Nebula (M1), the remnant of a supernova some 1,000 years ago.
But that’s old news. Recently, we got a much younger example — perhaps the youngest ever discovered. Estimated to be between 14 and 80 years old, the newcomer, called VT 1137-0337, lies in a dwarf galaxy 395 million light-years away. Astronomers first picked up its radio emission in 2018 in data from the Very Large Array (VLA) Sky Survey. It also appears in data from 2019, 2020, and 2022. But when the team went back to VLA observations of the same galaxy from 1998, there was no sign of it.
That means VT 1137-0337 has only recently become visible. Researchers tested several theories to explain the emission, from a supernova to a star falling into a black hole. Ultimately, says Dillon Dong, a Caltech graduate student who announced the find June 15 at the American Astronomical Society’s summer meeting and the lead author of a paper submitted to the Astrophysical Journal, “the most plausible origin of this nebula seems to be a pulsar wind, or potentially flares from a magnetar,” a type of super-magnetic neutron star. But, he notes, no radio nebulae have ever been detected around a magnetar, so he thinks it’s more likely a pulsar wind nebula. And the reason it’s suddenly popped up is that the nebula had been embedded within the debris of the supernova that created the neutron star. Only over time has that material expanded and thinned, finally allowing VT 1137-0337’s light to shine through.
VT 1137-0337 is some 10,000 times more energetic than the Crab and has a more powerful magnetic field. And “this thing is young enough that we can actually see it evolve on a human timescale,” Dong says. VT 1137-0337’s emission has faded 20 percent in just four years. In some 1,000 years, he adds, it will probably look like the pulsars and magnetars we’re used to finding around the Milky Way. So, this is a unique peek at the earliest stages of a neutron star’s life. For now, his team will continue monitoring VT 1137-0337 as well as use additional wavelengths to learn more about its properties. They will also look in existing and future survey data in the hopes of finding similar nebulae.
4. Landmark missions come to a close
While 2022 OPened many new doors, it was a time of closure as well. In April, NASA and the German Space Agency announced they would shut down the Stratospheric Observatory for Infrared Astronomy (SOFIA), which carried a 2.5-meter telescope aboard a Boeing 747SP airplane. Most infrared (IR) light is absorbed by water in Earth’s atmosphere. SOFIA flew above 99 percent of that water, allowing observations of the entire IR spectrum — a range even the James Webb Space Telescope cannot match. “SOFIA found its own niche … and used it to do science that isn’t possible from anywhere else,” says SOFIA instrument scientist Pete Ashton.
But the Astro2020 decadal survey stated SOFIA’s yearly operating price tag of $86 million USD — on par with the Hubble Space Telescope and Chandra X-ray Observatory — could not be justified by its “modest” scientific output. From 2014 to 2020, SOFIA flights resulted in 178 scientific papers; Hubble and Chandra data combined were used in more than 2,700 papers over the same period. So, on Sept. 28/29, SOFIA made its last flight from Palmdale, California.
“The loss of SOFIA simply means loss of access to the far-IR window for at least the next 10 years,” says Dario Fadda, a senior scientist at the SOFIA Science Center. He also worries researchers who might have worked on SOFIA’s IR data will move to other fields. But other astronomers, such as SOFIA principal engineer Nancy McKown, are hopeful such work won’t suffer long. “There may be some gaps now, but I’m confident that the thirst for knowledge will keep it in the long view of the big picture. After all, the data will still be there for us to capture in the future.”
Farther from home, another mission was wrapping up. Since late 2018, NASA’s InSight lander had listened for marsquakes, which reveal details about the Red Planet’s interior. InSight also sent back regular weather reports, shared the sounds of martian wind, and both heard and felt small space rocks fall through the thin atmosphere and strike the ground.
But survival on Mars is tough, and InSight’s power levels dropped as dust coated its solar panels. In April 2022, NASA said the mission would run through the end of the year “unless the spacecraft’s electrical power allows for longer operations.”
In late May, the lander stopped using its robotic arm. At that time, the team reported InSight’s solar panels were producing just one-tenth the power as when first deployed. By June, all instruments had been turned off — except the seismometer, which kept running about half the time instead of round the clock, says InSight Principal Investigator Bruce Banerdt.
Eventually, power levels will completely dry up and InSight will shut down. In late September, Banerdt noted that Mars’ dusty season was ramping up. He estimated the mission would end due to lack of power by January 2023.
But with data on more than 1,300 marsquakes and years of meteorological and acoustic information safely sent home, Banerdt says InSight’s contributions to science will continue for decades to come. “InSight’s legacy is pretty substantial. We’ve done the things that we went to Mars to do.” It took the first measurements of the thickness of the martian crust, determined the size and density of Mars’ core, and gleaned details of the structure and composition of the mantle. “It’s literally rewriting the textbooks on Mars,” he says.
When Insight does go quiet, “It’s gonna be a sad but proud moment,” says Banerdt. “But I think that the plucky little lander has actually earned a rest. It’s been working hard for us for a long time and I think it’s earned its retirement.”
3. NASA smacks an asteroid
At 7:14 p.m. EDT On Monday, Sept. 26, 2022, a 1,260-pound (570 kilograms) spacecraft traveling 14,000 mph (22,530 km/h) slammed directly into a small asteroid named Dimorphos, throwing out a massive cloud of debris.
The (pre-planned) hit was the culmination of NASA’s Double Asteroid Redirection Test (DART) to determine whether a “kinetic impact” — i.e., hitting an asteroid with a spacecraft — could alter its trajectory. The hope, should it work, was that a similar technique could be employed to redirect an asteroid on a collision course with Earth.
The test target, 525-foot-wide (160 meters) Dimorphos, is a moonlet orbiting the near-Earth asteroid (NEA) 65803 Didymos, which is roughly 0.5 mile (780 m) across. DART’s goal was to slightly shrink the orbit of Dimorphos around Didymos. Success would be measured by whether the impact altered Dimorphos’ nearly 12-hour period by at least 73 seconds.
On Oct. 11, NASA announced that Dimorphos’ 11-hour and 55-minute orbit had shortened to 11 hours and 23 minutes. The difference, 32 minutes, was roughly 26 times the mission’s baseline for success.
It was a watershed moment in the field of planetary defense, which aims to identify and mitigate risks to Earth from asteroids and comets that may cross our planet’s path. (It’s worth noting that of the more than 29,000 known NEAs in late 2022, none pose a significant risk. But there are likely many more yet to be found.) “As new data come in each day, astronomers will be able to better assess whether, and how, a mission like DART could be used in the future to help protect Earth from a collision with an asteroid if we ever discover one headed our way,” said NASA planetary science division director Lori Glaze in a press release.
Long after DART had smashed to smithereens, its target stayed in the spotlight. Images from ground- and space-based telescopes showed Dimorphos sporting first one, then two cometlike tails of dust and debris from the impact. One stretched at least 6,000 miles (10,000 km) long and persisted for more than a month. Watching their evolution has revealed details about Dimorphos’ composition and structure. Astronomers will continue to follow both asteroids through March, when celestial geometry renders them unobservable for a time. And a future European Space Agency mission, Hera, will visit the pair after launching in late 2024.
It may be difficult to move mountains, but NASA has showed that at least we can move small asteroids.
2. EHT images Milky Way’s monster black hole
In 2019, the Event Horizon Telescope (EHT) released its groundbreaking first image of a black hole 55 million light-years away in the galaxy M87. Ever since, the world had been eagerly awaiting a glimpse of the monster lurking at the center of our own Milky Way.
In 2022, we finally got it: On May 12, the EHT presented the first portrait of Sagittarius A* (abbreviated Sgr A*), a 4-million-solar-mass behemoth just 27,000 light-years away. Like the previous picture, it shows the shadow of the black hole’s event horizon, or point of no return, silhouetted against the bright plasma in its accretion disk. Some of the light in the glowing ring comes from behind the black hole, bent around it by gravity.
The image, created by observing the galactic center with a worldwide network of eight radio telescope arrays over several days and combining the results, is vital in many ways. Although astronomers had long surmised Sgr A* was a black hole, all evidence to this point had been secondhand. Scientists watched stars at the galactic center orbit a massive, invisible object and measured the radiation it released as it consumed material. The image, however, is direct evidence of Sgr A*’s nature.
But why did M87’s image come first? General relativity states that all black holes should look essentially the same. It also says the size of a black hole’s event horizon (and thus shadow) scales linearly with mass. A more massive black hole has a larger event horizon and its accretion disk sits farther out. At the same speed, orbiting material takes longer to circle a more massive black hole than a less massive one.
“The images that we’re making are not of the event horizon itself, but of high-energy electrons, this sort of super plasma, that’s swirling in this gravitational maelstrom about the event horizon,” says Nicholas MacDonald at the Max Planck Institute for Radio Astronomy in Bonn, Germany, the European outreach coordinator for EHT. “The characteristic timescale in M87* [M87’s black hole] is months to days that it takes for stuff to swirl around, and in contrast, in Sgr A*, because it’s such a smaller physical structure, that timescale is days to minutes.” So, Sgr A* was blurring itself out even as astronomers observed it, requiring two years of complex and careful processing to produce the final image.
Such images, MacDonald stresses, rely on a huge collaboration of hundreds of people working together. “You can’t do it unless you have these telescopes around the world,” he says.
For now, these are the only supermassive black holes EHT can image so closely, due to their size on the sky. But EHT is far from done. Next, “the EHT very much wants to make movies” of the orbiting plasma, says MacDonald, by observing both black holes multiple times a year. That will let us watch these monster black holes change with time on the smallest possible scale, something never before seen. “It’s a really fun time to be in this business,” he says.
1. The era of JWST begins
The top science story of 2022 is a tale more than two decades in the making. First considered in 1989 and formally recommended in 1996, NASA began construction of an infrared space telescope in 2004. Seventeen years later, at 7:20 A.M. EST on Dec. 25, 2021, the James Webb Space Telescope (JWST) launched from Kourou, French Guiana, aboard an Ariane 5 rocket.
The astronomical community rejoiced. But there was still much to do. As the telescope traveled to its destination at the L2 Lagrange point of Earth’s orbit, some 930,000 miles (1.5 million km) away, it began an intricate dance. The steps involved unfolding and locking its 6.5-meter mirror and tennis court-sized sunshield, both carefully stowed to fit inside the rocket fairing that carried it into space. If any step failed, there was no way to reach and repair the telescope.
“Every piece of this huge, gorgeous observatory was ingeniously designed, custom made, mostly by hand, and torture-chamber tested and re-tested,” wrote Jane Rigby, JWST operations project scientist at NASA’s Goddard Space Flight Center, in a blog the day of launch. “So many hands cradled this bird. So many brains dreamed up science observations. So many worked so hard — now we see if it works.”
It did. By Jan. 4, 2022, the sunshield had fully deployed. The next day, the scope’s secondary mirror was in place, and by Jan. 8, the primary mirror had unfolded. On Jan. 24, JWST arrived at L2. Then came months of cooling the telescope’s optics, aligning its mirror segments, and turning on and checking its four instruments. Initial test images showed tantalizing hints of target stars and even background galaxies in exquisite detail.
Finally, NASA announced it would publicly release the telescope’s first images July 12. But U.S. President Joe Biden surprised the world one day early, on July 11, by presenting the deepest, sharpest infrared image ever taken, showing the distant galaxy cluster SMACS 0723. The next day, the JWST team released four additional groundbreaking images: the Southern Ring planetary nebula, Stephan’s Quintet of galaxies, the star-forming region NGC 3324 in the Carina Nebula, and the spectrum of the gas giant exoplanet WASP-96 b. Each showed a new view of our universe, from potential water and haze in an exoplanetary atmosphere to forming stars amid galactic dust and gas.
Since then, new photos and discoveries have come at a rapid pace — some as official press releases, others shared by researchers eager to show how JWST is already revolutionizing science. Targets have included solar system planets like Jupiter (see page 36) and Neptune, as well as distant objects such as the earliest known star, Earendel. In early September, JWST directly imaged its first exoplanet, a gas giant several times Jupiter’s mass.
The telescope is off to an auspicious start. And it is only the start. JWST has enough propellant to continue doing science for over a decade — more than twice its minimum mission lifetime of five years. Throughout commissioning, the team repeatedly reported its optics were performing above baseline benchmarks. In a nutshell, JWST is performing better than expected and has the capability to do so for more than a decade.
“Our immense golden telescope is seeing where none have seen before, discovering what we never knew before, and we are proud of what we have done,” said JWST senior project scientist John Mather in a NASA interview. “Webb was worth the wait!”
Stories to watch for in 2023
- The Indian Space Research Organisation expects to launch the Chandrayaan-3 lunar lander and the Aditya-L1 solar observatory in early 2023.
- ESA plans to launch the JUpiter ICy moons Explorer (JUICE) between April 5 and 25, 2023.
- The ESA’s BepiColombo mission will make its next Mercury flyby June 20, 2023.
- In June 2022, NASA delayed the planned launch of its Psyche mission to the asteroid of the same name. The next launch windows open in July and September 2023.
- NASA’s OSIRIS-REx will deliver its sample of asteroid 101955 Bennu to Earth Sept. 24, 2023.