Space

Observations of thousands of white dwarf stars have confirmed a decades-old theory about the relationship between their masses and sizes. More

Small, frequent lightning storms zip across Jupiter’s cloud tops. NASA’s Juno spacecraft spotted the flashes for the first time, scientists report August 5 in Nature.
“It’s a very exotic thing that doesn’t exist on Earth,” says physicist Heidi Becker of NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
Previous spacecraft have revealed high-energy “superbolts” on Jupiter. That lightning originates 50 to 65 kilometers below Jupiter’s cloud tops, where liquid water droplets form. Scientists think superbolts form like lightning on Earth does: Colliding ice crystals and water droplets charge each other up, then stretch the charge between them when they separate (SN: 6/25/20).
Juno, which arrived at Jupiter in 2016, got much closer to the giant planet’s cloud tops than previous missions. Becker and her team turned the spacecraft’s navigation camera — which normally observes stars to track Juno’s position — on Jupiter’s nightside in February 2018. To the team’s surprise, the clouds crackled with electricity.
Newly observed lightning showed up as bright dots (indicated with arrows) on Jupiter’s nightside, seen in this composite image from two of Juno’s cameras. The insets are pixelated representations of the events’ brightness (yellow is more bright; blue is less bright).H.N. Becker et al/Nature 2020
Superbolts are up to 100,000 times as strong as these small flashes. But the cloud-top lightning is 10 times as frequent. Strangely, the smaller bolts appeared to come from just 18 kilometers below the cloud tops, where it’s too cold for liquid water to exist alone.
Shallow lightning must have a different origin than the deeper lightning, Becker says. Perhaps ammonia in the upper cloud decks acts as antifreeze, creating droplets of ammonia and water combined. Juno has also seen evidence that violent storms in deeper cloud layers sometimes toss ice crystals high above where they’re normally found. When those crystals collide with the ammonia-water droplets, they may charge up and create lightning, Becker and her colleagues reason.
Similar small lightning storms may happen on other planets, including exoplanets, Becker says (SN: 5/13/16). “Every time you have a new realization, it feeds into new theories that will be developed not only for our solar system but for other solar systems.” More

An observatory in the heart of Antarctica could have the world’s clearest views of the night sky.
If an optical telescope were built on a tower a few stories tall in the middle of the Antarctic Plateau, it could discern celestial features about half the size of those typically visible to other observatories, researchers report online July 29 in Nature. The observatory would achieve such sharp vision by peering above the atmosphere’s lowermost layer, known as the boundary layer, responsible for much of the undulating air that muddles telescope images (SN: 10/4/18).
The thickness of Earth’s boundary layer varies across the globe. Near the equator, it can be hundreds of meters thick, limiting the vision of premier optical telescopes in places like the Canary Islands and Hawaii (SN: 10/14/19). Those telescopes usually cannot pick out celestial features smaller than 0.6 to 0.8 arc seconds — the apparent width of a human hair from about 20 meters away.
“But in Antarctica, the boundary layer is really thin,” says Bin Ma, an astronomer at the Chinese Academy of Sciences in Beijing, “so it is possible to put a telescope above.”
Ma and colleagues took the first-ever measurements of nighttime atmospheric blur from the highest point in East Antarctica, called Dome A. From April to August 2019, instruments on an 8-meter-tall tower at China’s Kunlun research station tracked how Earth’s atmospheric turbulence distorted incoming starlight. A nearby weather station also monitored atmospheric conditions, such as temperature and wind speed. Using these observations, researchers characterized the boundary layer at Dome A and its effect on telescope observations.
From April to August 2019, instruments atop an 8-meter-tall tower at China’s Kunlun research station in East Antarctica observed how the local atmosphere distorted light from celestial objects.Zhaohui Shang
The boundary layer was, on average, about 14 meters thick; as a result, the light sensors at the top of the 8-meter tower were completely free of boundary layer blur only about one-third of the time. But when these instruments were above the layer, atmospheric interference was so low that a telescope could pick out details on the sky 0.31 arc seconds across, on average. The best recorded atmospheric conditions would let a telescope see features as small as 0.13 arc seconds.
“One-tenth of an arc second is extremely good,” says Marc Sarazin, an applied physicist at the European Southern Observatory in Munich who was not involved in the work. This is “really something you rarely achieve in Chile or on Mauna Kea” in Hawaii.
Researchers have found similarly excellent visibility above the boundary layer at another spot on the Antarctic Plateau, known as Dome C. But the boundary layer there is around 30 meters thick — making it more difficult to build an observatory above it. An optical telescope planned for construction on a 15-meter tower at Kunlun could take advantage of Dome A’s stellar views above the boundary layer, Ma says. Such crisp telescope images could help astronomers study a range of celestial objects, from solar system bodies to distant galaxies.

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Megan Barrington watched the sun rise over the rocky outcrop. When light struck at exactly the right angle, she mounted a gizmo that looked like eye exam equipment on a tripod and aimed it at the spot. The goal: gather evidence that this windswept wilderness once teemed with life, and then beam the information to her colleagues back home.
Soon, a version of that setup (minus Barrington) will be deployed on Mars. The state-of-the-art, zoomable, multispectral camera is part of the toolkit on NASA’s Perseverance rover (SN: 7/28/20). “That instrument is going to allow me to look at the mineralogy of Mars at Jezero crater,” the rover’s landing spot, says Barrington, a planetary scientist at Cornell University.
The rover is scheduled to launch to Mars on July 30. A February role-playing exercise in the Nevada desert by Barrington and six colleagues was a kind of dress rehearsal for the rover’s various instruments. Another 150 team members around the world played the “Earth” team during those two weeks, sending commands from remote mission control and receiving data as it would appear coming from the real rover.
“We’re not just simulating a Mars mission,” says engineer Raymond Francis of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who organized and led the trip. “We’re simulating a specific Mars mission by presenting data … to the people who designed the instrument that will take that data. So the standard is high not to look like clowns.”

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Perseverance has the most demanding and ambitious to-do list of any rover yet: seek signs of past Martian life, prepare the way for future human missions and collect at least 20 samples of Martian rock for eventual return to Earth. And that’s just in its first two years. For contrast, Curiosity rover has drilled a few dozen holes over eight years on Mars, and didn’t store any of those samples for later (SN: 7/7/18, p. 8).
The dress rehearsal in the desert will help ensure that when Perseverance lands on the Red Planet in February 2021, its handlers on Earth can get straight to the science.
“We don’t want to get there and learn how to explore Mars while on Mars,” Francis says. “We want [team members] to be ready when the rover hits the ground.”
Water marks the spot
The first order of business was to find the right spot for the dry run. “We had to pick a site that kind of looked like Mars,” Francis says. “The parking lot would not do.” The team wanted the site to look as Mars-like as possible, no factories, footprints or foliage to break the illusion.
An ideal site would have geology that echoed Jezero crater, which is thought to be the remnants of an ancient lakebed and river delta (SN: 11/19/18). It also had to be within a few hours’ drive of JPL, and not totally off the grid — the rover team slept in hotels, ate dinner in restaurants and had reliable Wi-Fi to send data to the Earth team every night.
The final requirement was that it be someplace the Earth team hadn’t seen before. If mission control members recognized the site, they could bias their findings with what they already knew.
Engineer and team leader Raymond Francis gets up close with the rocks to make a measurement.JPL-Caltech/NASA
“Most of the popular Mars analogs are already well known to the Mars community,” Francis says. “So we had to be a little sneaky.”
Previous exercises, in November 2017 and February 2019, were run in the Mojave Desert in California. For 2020, the rover team headed to Walker Lake in western Nevada. The lake’s water has been receding for a thousand years, so there are spots near the ancient shoreline where the present-day lake is invisible.
Walker Lake’s rocks preserved a cornucopia of biological signals for the ground team to discover: fossilized fish bones and shells of tiny shrimplike crustaceans called ostracods, which are not expected on Mars; and microbial fossils called stromatolites, which could plausibly be found in Jezero crater (SN: 10/17/18).
Toolkit
Francis and his team brought handheld versions of almost all the rover’s instruments to gather whatever data the Earth team requested. They had a drill, handheld spectrometers, lasers, a ground-penetrating radar that they transported in a jogging stroller, plus several elaborate camera setups to represent the rover’s navigation, hazard avoidance and zoomable 3-D science cameras.
Perhaps the most important piece of equipment was the broom used for sweeping away footprints. It became a running joke, Francis says: “We’ve got all this equipment, a multibillion-dollar mission, and it’s all hinging on this 99-cent broom.”
Almost everything went smoothly. But a few days into the mission, Barrington’s zoomable camera had “a major malfunction,” she says. She framed her shot, and…. nothing happened. The camera wasn’t getting any power, she realized. “I took it apart and rewired many pieces, to no avail,” she says.
She and her teammates finally realized one of the power adapters had completely blown. She had to drive two hours to the nearest city to get a new one.
Of course, driving into town to get a new part won’t be an option on Mars. The real camera, called Mastcam-Z, has been through weeks of rigorous testing and calibration, and is probably up to the task. But “we all go into missions knowing that sometimes irreversible mistakes occur,” Barrington admits. “All we can do at that point is use the instruments to the fullest capacity of which they are capable of operating.”
Planetary scientist Megan Barrington adjusts her instrument, a multispectral, zoomable camera standing in for Perseverance’s Mastcam-Z.JPL-Caltech/NASA
Signs of life, big and small
There was one major giveaway that the team was actually on Earth. “This is very much middle-of-nowhere desert, which is good,” Francis says. But the rover site was mere steps from a U.S. Department of Defense munitions facility, one of the largest in the world.
“It was really something to behold,” Barrington says. “They had hundreds of bunkers lined up in rows as far as you could see…. All of that was one very crooked metal fence away from us.”
More than once, military police showed up to check the team’s credentials. “I had to approach them and say, hello, people with the guns, I need you to stop walking now,” Francis says. “We’re running a Mars rover simulation and we don’t want you to put your footprints in this sand.”
Despite Francis and colleagues’ best efforts, the bunkers showed up in a few photos. The ground team gamely ignored them, apart from a few jokes about SpaceX founder Elon Musk building a Martian city.
By the end of the two-week exercise, the remote science team reviewing the data had noticed the ostracods and fishbones, and started exploring the stromatolites. “They were doing a good job of finding the biomarkers,” Francis says, who now has hope that “if Mars is hiding stromatolites, maybe we’ll see them.”
Coming home to quarantine
The field trip ended on February 27, just as awareness of the novel coronavirus SARS-CoV-2 was rising in the United States. By March 15, JPL told employees to work from home. “We only had a few days together before we were all on remote work,” Francis says.
The pandemic has already contributed to the delay of the launch of the European and Russian ExoMars rover, which was also supposed to launch in July (SN: 3/12/20).  If Perseverance misses the late July to early August launch window, the rover can’t head to Mars until 2022.
If the pandemic is still an issue by the time the rover lands in February, Francis doesn’t know what the team will do. “But,” he says, “the good news is the mission is designed for remote operations.” More

Science writer Kate Greene couldn’t have known that her memoir about her time on a make-believe Mars mission would be published as millions of people on Earth isolated themselves in their homes for months amid a pandemic.

But her book is one of two about Mars published this month that are oddly well-suited to the present moment. Once Upon a Time I Lived on Mars and Sarah Stewart Johnson’s The Sirens of Mars are both about exploration. Yet they’re also about many different types of isolation and the human yearning to not be alone.
Greene participated in a mock Mars mission, called HI-SEAS, for Hawaii Space Exploration Analog and Simulation, in 2013. She and five others lived in a dome on a rocky, barren patch atop Mauna Loa volcano for four months with no fresh food, no fresh air (all excursions were conducted in clunky “spacesuits”) and no instantaneous contact with the outside world.
NASA and other space agencies run such missions to figure out best practices for keeping astronauts sane and productive in isolated and stressful environments. It’s well-documented that boredom can lead to mistakes or inattention. Other simulated Mars missions suggest that astronauts isolated together could develop an us-versus-them mentality that would lead the crew to stop listening to mission control, which could be dangerous on a long mission.

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With humor and sensitivity, Greene relates how her crew got along (or didn’t), what she read, what she ate and the time-delayed e-mails she exchanged with loved ones back on “Earth.” Through the book’s series of essays, she uses the mission as a lens to examine everything from the ethics and economics of space travel to the nature of time, love and home.
Her descriptions of boredom and seclusion feel especially apt in a time of social distancing: “the way certain aspects of your environment, daily schedule and conversations smooth over, lose their texture.” Greene relates her experience to astronaut Michael Collins’ time orbiting in the Apollo 11 capsule alone while his crewmates walked on the moon. She connects both of those experiences to that of her brother, who spent the last year and a half of his life confined to a hospital room.
“On this oasis of a planet,” she writes, “there are so many ways to feel isolated, each of us with the potential to sit with the terror of being alive and possibly alone in the cosmos.”

The Sirens of Mars starts with a much broader view of Mars exploration. In lyrical, engaging writing, Stewart Johnson, a planetary scientist, chronicles how our perception of Mars has swung from a world teeming with life, to definitely dead and boring, and back again over and over since the invention of telescopes.
Stewart Johnson brings together a cast of characters to tell this history, from Galileo to the present-day team working on the Curiosity rover. Those characters include astronomer Carl Sagan, whose Cosmos TV series Stewart Johnson watched as a child. Sagan was almost ridiculed out of science for his obsession with “exobiology.”
She also introduces less famous but equally important people, like Sagan’s colleague Wolf Vishniac, whose “Wolf Trap” life-detection experiment was cut from NASA’s life-hunting Viking landers in the 1970s. To get over his disappointment, Vishniac went searching for microbes in Antarctica and died in an accident there before the Viking missions launched (SN: 12/22/73).
In this sweeping history of human fascination with the Red Planet, Stewart Johnson also tells a personal story of finding her place in the world, from an inquisitive child to an unrooted adventurer to a wife and mother and member of a scientific team.
She makes a clear case that the search for life on Mars is an effort to not be alone. In one of the most poignant scenes in her book, she is hiking on Mauna Kea — the next volcano over from Greene’s Mars habitat — and finds a fern growing amid the volcanic desolation.
“It was then, on that trip, that the idea of looking for life in the universe began to make sense to me,” she writes. “I suddenly saw something I might haunt the stratosphere for, something for which I’d fall into the sea…. a chance to discover the smallest breath in the deepest night and, in so doing, vanquish the void that lurked between human existence and all else in the cosmos.”
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A new map of the entire sky, as seen in X-rays, looks deeper into space than any other of its kind. The map, released June 19, is based on data from the first full scan of the sky made by the eROSITA X-ray telescope onboard the Russian-German SRG spacecraft, which launched in July 2019. The […] More

A dense, scorched planet around a faraway star may be the naked core of a gas giant. Satellite and Earth-based telescope observations show that the newly discovered exoplanet has a radius nearly 3.5 times Earth’s and a mass about 39 times as big. Those dimensions combined point to a density roughly the same as Earth’s, […] More

In spite of their dark reputations, two black holes may have set off a cosmic light show. Subtle gravitational rumbles from a collision of two black holes may have been accompanied by a flare of light about a month later, physicists report June 25 in Physical Review Letters. It’s a surprising conclusion given black holes’ […] More