Ingenuity is still flying on Mars. Here’s what the helicopter is up to

The Ingenuity Mars helicopter was never supposed to last this long. NASA engineers built and tested the first self-powered aircraft to fly on another planet to answer a simple question: Could the helicopter fly at all? The goal was to take five flights in 30 Martian days or break the aircraft trying.

But more than 120 Martian days past that experiment window, Ingenuity is still flying and doing things no one ever expected. The helicopter, which took its first flight on April 19, is breaking its own records for distance and speed (SN: 4/19/21). It’s helping the Perseverance rover explore Jezero crater, near an ancient river delta that may hold signs of past Martian life (SN: 2/17/21). And Ingenuity is coping with changing seasons and navigating over rough terrain, two things that the flier wasn’t designed to do.

“It’s gotten into a good groove,” says Ingenuity’s original chief engineer Bob Balaram NASA’s Jet Propulsion Lab in Pasadena, Calif. “It’s in its element and having fun.”

Here’s what Ingenuity has been up to on Mars.
Testing the limits
Ingenuity is flying farther, faster and higher than it did in its first few flights. The helicopter has lifted itself a maximum of 12 meters above the Martian surface, zipped along at up to five meters per second (about half as fast as record-setting sprinter Florence Griffith-Joyner) and covered 625 meters (about a third the length of the Kentucky Derby) in a single flight. These extremes give engineers valuable information about the limits of flying on Mars.

“We are still trying to learn lessons,” says JPL robotics engineer Teddy Tzanetos, a team leader for the Ingenuity mission. “Flight after flight, we’re learning the boundaries of performance.”
Early on, Ingenuity tested its limits in a way that the flight team really didn’t plan for. During its sixth flight on May 22, the helicopter’s navigation system suffered a glitch that made it roll and sway alarmingly.

The helicopter’s navigation software keeps track of the craft’s position by taking an image, reading the time stamp on that image and predicting what the camera should see next based on landmarks from previous photos that Ingenuity took. If the next image doesn’t match that prediction, the software corrects the helicopter’s position and velocity to match up better.

Less than a minute into the May 22 flight, a single image got lost on its way from Ingenuity’s cameras to its onboard computer. That meant that the time stamps on all subsequent images were a little off. In trying to correct what it perceived as errors, Ingenuity “went on a wild joyride,” Balaram says.

Luckily, the helicopter touched down safely within five meters of its intended landing spot. The anomaly was a blessing in disguise, Balaram says. It put the helicopter through extremes of movement — “how aggressively you can move the joystick, if you will” — that the engineers would not have asked it to do on purpose, and did perfectly fine, he says.

“It’s a serendipitous thing that we got that flight experience under our belt,” Balaram says. “We have much more confidence in the vehicle.”

Doing science
Originally, the helicopter team wanted to push the vehicle until it broke. But now the researchers are flying more cautiously and less often. That’s because the helicopter is currently supporting the Perseverance rover in doing science (SN: 4/30/21).

“We’re no longer in the Month of Ingenuity,” Tzanetos says. “We’re a small part of a much larger team.”

The helicopter has already proven its worth by telling the rover where not to go. Ingenuity’s ninth flight, on July 5, took the helicopter over a dune field called South Séítah that would have been difficult for the rover to drive through safely. Then, Ingenuity photographed some rock outcrops and raised ridges in South Séítah that had looked interesting in images taken from an orbiting spacecraft. Scientists thought those ridges could record some of the deepest water environments in the lake that filled the crater long ago.
In 3-D images from the helicopter, it turned out that those ridges did not show the layers that would have indicated that the rocks formed in deep water. The rover team decided to move on, saving Perseverance a long, arduous and potentially dangerous drive.

“They didn’t have to send the rover all the way to this particular target, and then realize, hey, this may not be the highest priority thing,” Balaram says.

Scouting for the rover has also taken Ingenuity over terrain that the helicopter wasn’t designed to understand. Ingenuity’s navigation software was programmed to assume that the ground beneath it is always flat because that was the type of terrain selected for that experimental first month of flight demonstrations.

“It was a perfectly reasonable simplification for a technology demonstration,” Balaram says. “But it was baked in. And now you’re stuck with a system with a flat ground assumption.”

When the helicopter is flying over a sloped surface, some features seem to move faster in its view than they would if the ground were flat, giving the helicopter a false sense of its motion. “The onboard navigation has no way of explaining it, except for thinking maybe I’m turning or spinning a bit,” Balaram says. The helicopter ends up veering to the side.

The team has come up with some work-arounds, such as choosing large enough landing zones that a precision landing isn’t necessary and slowing down when flying over rough terrain.

Coping with seasons
The air on Mars is notoriously thin (SN: 7/14/20). But since mid-September, the atmosphere in Jezero crater has been getting even thinner. As that part of Mars shifts from spring to summer, the air density has gone from about 1.5 percent of Earth’s at sea level, to about 1 percent.

That doesn’t sound like a big difference, but it’s enough that Ingenuity has had to spin its rotor blades faster to stay aloft. In October, the helicopter increased its rotor speed to 2,700 revolutions per minute, compared with a previous maximum of 2,537 rpm.
At that faster spin speed, the helicopter can fly for only 130 seconds at a time instead of the 170 seconds it managed before, without running the risk of the motors overheating.

That would be fine if the helicopter was just going to hang around the rover in one area, Tzanetos says. But the Mars duo’s next task is a race to the long-dry river delta at the mouth of Jezero crater. The Perseverance team hopes to cover hundreds of meters each Martian day. The farthest Ingenuity has covered in a day is 625 meters, and that was with the lower spin speed.

“It’ll be challenging to keep up,” Tzanetos says.

There’s no technical reason why Ingenuity can’t make it, though, Balaram says. “It’s certainly possible that one day it just won’t wake up. Or a landing will be a failure and we’ll never hear from it again because it tipped over,” he admits. “Those are rolls of the dice, there’s nothing inevitable about those. Barring that, it should keep working for many months.”

Inspiring future fliers
Meanwhile, engineers are already dreaming of the next Martian aircraft.

“Ingenuity is very exciting, we’re breaking a lot of ground,” Tzanetos says. “The whole point of it is to be that foundation. The important thing is what comes next.”

Current blueprints include a scaled-up version of Ingenuity that could carry more equipment and work alone or with a rover, and a large hexacopter, with six rotors arranged around a central ring. A craft like that could cover more ground more quickly than a rover, traveling distances that could take Perseverance multiple years in just a few months.

A white paper submitted to the 2023–2032 planetary science and astrobiology decadal survey — a once-a-decade review of the fields’ goals and priorities — suggests several possible missions for a Mars Science Helicopter. In one, the craft could take samples of clay minerals at a site like Mawrth Vallis, a channel thought to be carved by a long-ago flood.
Mawrth was a finalist for the last two Mars rover landing sites and is a contender for the European Space Agency’s Rosalind Franklin rover, set to launch in 2022. Clays can preserve organic material on Earth, so a mission to Mawrth could search for signs of life.

A helicopter could also explore craters with water ice deposits with slopes too steep for rover wheels. And by taking measurements at several different altitudes, the helicopter could help figure out how the atmosphere exchanges gases with the ground, which could help solve the mystery of when and how Mars lost its liquid water (SN: 11/12/20). Or a helicopter could map the magnetic field of large swaths of the Martian surface, revealing when and how the Red Planet lost its molten core (SN: 2/24/20).

And whenever astronauts get around to visiting Mars, “it might be useful to have fleets of drones zipping around the skies, carrying loads or scouting ahead,” Tzanetos says. “That’s the exciting future I’m looking forward to.”

2021 research reinforced that mating across groups drove human evolution

Evidence that cross-continental Stone Age networking events powered human evolution ramped up in 2021.

A long-standing argument that Homo sapiens originated in East Africa before moving elsewhere and replacing Eurasian Homo species such as Neandertals has come under increasing fire over the last decade. Research this year supported an alternative scenario in which H. sapiens evolved across vast geographic expanses, first within Africa and later outside it.

The process would have worked as follows: Many Homo groups lived during a period known as the Middle Pleistocene, about 789,000 to 130,000 years ago, and were too closely related to have been distinct species. These groups would have occasionally mated with each other while traveling through Africa, Asia and Europe. A variety of skeletal variations on a human theme emerged among far-flung communities. Human anatomy and DNA today include remnants of that complex networking legacy, proponents of this scenario say.

It’s not clear precisely how often or when during this period groups may have mixed and mingled. But in this framework, no clear genetic or physical dividing line separated Middle Pleistocene folks usually classed as H. sapiens from Neandertals, Denisovans and other ancient Homo populations.
“Middle Pleistocene Homo groups were humans,” says paleoanthropologist John Hawks of the University of Wisconsin–Madison. “Today’s humans are a remix of those ancient ancestors.”

New fossil evidence in line with that idea came from Israel. Braincase pieces and a lower jaw containing a molar tooth unearthed at a site called Nesher Ramla date to between about 140,000 and 120,000 years ago. These finds’ features suggest that a previously unknown Eurasian Homo population lived at the site (SN Online: 6/24/21), a team led by paleoanthropologist Israel Hershkovitz of Tel Aviv University reported. The fossils were found with stone tools that look like those fashioned around the same time by Middle Easterners typically classified as H. sapiens, suggesting that the two groups culturally mingled and possibly mated.

Interactions like these may have facilitated enough mating among mobile Homo populations to prevent Nesher Ramla inhabitants and other Eurasian groups from evolving into separate species, Hershkovitz proposed.

But another report provided a reminder that opinions still vary about whether Middle Pleistocene Homo evolution featured related populations that all belonged to the same species or distinct species. Researchers studying the unusual mix of features of a roughly 146,000-year-old Chinese skull dubbed it a new species, Homo longi (SN Online: 6/25/21). After reviewing that claim, however, another investigator grouped the skull, nicknamed Dragon Man, with several other Middle Pleistocene Homo fossils from northern China.

If so, Dragon Man — like Nesher Ramla Homo — may hail from one of many closely related Homo lines that occasionally mated with each other as some groups moved through Asia, Africa and Europe. From this perspective, Middle Pleistocene Homo groups evolved unique traits during periods of isolation and shared features as a result of crossing paths and mating.
Back-and-forth migrations by Homo groups between Africa and Asia started at least 400,000 years ago, discoveries in Saudi Arabia suggest (SN: 10/9/21 & 10/23/21, p. 7). Monsoon rains periodically turned what’s now desert into a green passageway covered by lakes, wetlands and rivers, reported archaeologist Huw Groucutt of the Max Planck Institute for the Science of Human History in Jena, Germany, and colleagues. Each of five ancient lake beds identified at a Saudi site once hosted hunter-gatherers who left behind stone tools.

Occupations occurred intermittently between about 400,000 and 55,000 years ago. By about 200,000 years ago, stone tools at one of the lake beds resembled those made around the same time by H. sapiens in northeastern Africa. Some of those Africans may have stopped for a bit in a green Arabia before trekking into southwestern Asia, Groucutt suggests.

Either H. sapiens or Neandertals made stone tools unearthed in the youngest lake bed. Neandertals inhabited parts of the Middle East by around 70,000 years ago and could have reached a well-watered Arabia by 55,000 years ago. If that’s what happened, Neandertals may have mated with H. sapiens already there, Groucutt speculates.

Although Arabian hookups have yet to be detected in ancient DNA, European Neandertals and H. sapiens mated surprisingly often around 45,000 years ago (SN: 5/8/21 & 5/22/21, p. 7), other scientists reported. DNA extracted from H. sapiens fossils of that age found in Bulgaria and the Czech Republic indicates that these ancient individuals possessed between about 2 percent and 4 percent Neandertal ancestry, a large amount considering H. sapiens migrants had only recently arrived in Europe.

So even after the Middle Pleistocene, networking among ancient Homo groups may have helped make us who we are today.

The cosmic ‘Cow’ may have produced a new neutron star or black hole

A cosmic flare-up called the Cow seems to have left behind a black hole or neutron star.

When the flash was spotted in June 2018, astronomers debated its origins. Now, astrophysicist DJ Pasham of MIT and colleagues have seen the first direct evidence of what the Cow left behind. “We may be seeing the birth of a black hole or neutron star,” Pasham says.

The burst’s official, random designation is AT2018cow, but astronomers affectionately dubbed it the Cow. The light originated about 200 million light-years away and was 10 times as bright as an ordinary supernova, the explosion that marks the death of a massive star.

Astronomers thought the flare-up could have been from an unusual star being eaten by a black hole or from a weird sort of supernova that left behind a black hole or neutron star (SN: 6/21/19).

So Pasham and colleagues checked the Cow for flickering X-rays, which are typically produced close to a compact object, possibly in a disk of hot material around a black hole or on the surface of a neutron star.

Flickers in these X-rays can reveal the size of their source. The Cow’s X-rays flicker roughly every 4 milliseconds, meaning the object that produces them must be no more than 1,000 kilometers wide. Only a neutron star or a black hole fits the bill, Pasham and colleagues report December 13 in Nature Astronomy.

Because the Cow’s flash was from the explosion that produced either of these objects, a preexisting black hole was probably not responsible for the burst. Pasham admits he was hoping for a black hole eating an exotic star. “I was a little bit disappointed,” he says. “But I’m more blown away that this could be direct evidence of the birth of a black hole. This is an even cooler result.”

50 years ago, chemical pollutants were linked to odd animal behavior

For fish and other underwater life, a sensitivity to chemicals plays the same role as the sense of smell does for land animals.… [Researchers] have been studying the subtle ways this delicate fish-communication system can be disrupted by pollutants…. One study examined the effects of kerosene pollution on the behavior of lobsters…. The experiments demonstrate that chemical communication interference takes place at extremely low dilutions.

Update
Chemical pollution — from sewage and agricultural runoff to pharmaceutical waste — muddles aquatic animals’ senses with potentially dire effects, decades of research has shown. A chemical used to treat sewage seems to limit some fish species’ abilities to form schools, making the fish vulnerable to predators (SN: 10/27/07, p. 262). Drug-tainted waters can have a variety of effects on fish, including suppressing their appetites (SN: 12/20/08, p. 15). A plastic chemical also appears to confuse senses: Its scent can lure sea turtles into eating plastic debris (SN: 3/28/20, p. 14).

How AI can help forecast how much Arctic sea ice will shrink

In the next week or so, the sea ice floating atop the Arctic Ocean will shrink to its smallest size this year, as summer-warmed waters eat away at the ice’s submerged edges.

Record lows for sea ice levels will probably not be broken this year, scientists say. In 2020, the ice covered 3.74 million square kilometers of the Arctic at its lowest point, coming nail-bitingly close to an all-time record low. Currently, sea ice is present in just under 5 million square kilometers of Arctic waters, putting it on track to become the 10th-lowest extent of sea ice in the area since satellite record keeping began in 1979. It’s an unexpected finish considering that in early summer, sea ice hit a record low for that time of year.

The surprise comes in part because the best current statistical- and physics-based forecasting tools can closely predict sea ice extent only a few weeks in advance, but the accuracy of long-range forecasts falters. Now, a new tool that uses artificial intelligence to create sea ice forecasts promises to boost their accuracy — and can do the analysis relatively quickly, researchers report August 26 in Nature Communications.

IceNet, a sea ice forecasting system developed by the British Antarctic Survey, or BAS, is “95 percent accurate in forecasting sea ice two months ahead — higher than the leading physics-based model SEAS5 — while running 2,000 times faster,” says Tom Andersson, a data scientist with BAS’s Artificial Intelligence lab. Whereas SEAS5 takes about six hours on a supercomputer to produce a forecast, IceNet can do the same in less than 10 seconds on a laptop. The system also shows a surprising ability to predict anomalous ice events — unusual highs or lows — up to four months in advance, Andersson and his colleagues found.
Tracking sea ice is crucial to keeping tabs on the impacts of climate change. While that’s more of a long game, the advanced notice provided by IceNet could have more immediate benefits, too. For instance, it could give scientists the lead time needed to assess, and plan for, the risks of Arctic fires or wildlife-human conflicts, and it could provide data that Indigenous communities need to make economic and environmental decisions.

Arctic sea ice extent has steadily declined in all seasons since satellite records began in 1979 (SN: 9/25/19). Scientists have been trying to improve sea ice forecasts for decades, but success has proved elusive. “Forecasting sea ice is really hard because sea ice interacts in complex ways with the atmosphere above and ocean below,” Andersson says.
Existing forecast tools put the laws of physics into computer code to predict how sea ice will change in the future. But partly due to uncertainties in the physical systems governing sea ice, these models struggle to produce accurate long-range forecasts.

Using a process called deep learning, Andersson and his colleagues loaded observational sea ice data from 1979 to 2011 and climate simulations covering 1850 to 2100 to train IceNet how to predict the state of future sea ice by processing the data from the past.

To determine the accuracy of its forecasts, the team compared IceNet’s outputs to the observed sea ice extent from 2012 to 2020, and to the forecasts made by SEAS5, the widely cited tool used by the European Centre for Medium-Range Weather Forecasts. IceNet was as much as 2.9 percent more accurate than SEAS5, corresponding to a further 360,000 square kilometers of ocean being correctly labeled as “ice” or “no ice.”

What’s more, in 2012, a sudden crash in summer sea ice extent heralded a new record low extent in September of that year. In running through past data, IceNet saw the dip coming months in advance. SEAS5 had inklings too but its projections that far out were off by a few hundred thousand square kilometers.

“This is a significant step forward in sea ice forecasting, boosting our ability to produce accurate forecasts that were typically not thought possible and run them thousands of times faster,” says Andersson. He believes it’s possible that IceNet has better learned the physical processes that determine the evolution of sea ice from the training data while physics-based models still struggle to understand this information.

“These machine learning techniques have only begun contributing to [forecasting] in the last couple years, and they’ve been doing amazingly well,” says Uma Bhatt, an atmospheric scientist at the University of Alaska Fairbanks Geophysical Institute who was not involved in the new study. She also leads the Sea Ice Prediction Network, a group of multidisciplinary scientists working to improve forecasting.

Bhatt says that good seasonal ice forecasts are important for assessing the risk of Arctic wildfires, which are tied strongly to the presence of sea ice (SN: 6/23/20). “Knowing where the sea ice is going to be in the spring could potentially help you figure out where you’re likely to have fires — in Siberia, for example, as soon as the sea ice moves away from the shore, the land can warm up very quickly and help set the stage for a bad fire season.”

Any improvement in sea ice forecasting can also help economic, safety and environmental planning in northern and Indigenous communities. For example, tens of thousands of walruses haul out on land to rest when the sea ice disappears (SN: 10/2/14). Human disturbances can trigger deadly stampedes and lead to high walrus mortality. With seasonal ice forecasts, biologists can anticipate rapid ice loss and manage haul-out sites in advance by limiting human access to those locations.

Still, limitations remain. At four months of lead time, the system was about 91 percent accurate in predicting the location of September’s ice edge.IceNet, like other forecasting systems, struggles to produce accurate long-range forecasts for late summer due, in part, to what scientists call the “spring predictability barrier.” It’s crucial to know the condition of the sea ice at the start of the spring melting season to be able to forecast end-of-summer conditions.

Another limit is “the fact that the weather is so variable,” says Mark Serreze, director of the National Snow and Ice Data Center in Boulder, Colo. Though sea ice seemed primed to set a new annual record low at the start of July, the speed of ice loss ultimately slowed due to cool atmospheric temperatures. “We know that sea ice responds very strongly to summer weather patterns, but we can’t get good weather predictions. Weather predictability is about 10 days in advance.”

This eco-friendly glitter gets its color from plants, not plastic

All that glitters is not green. Glitter and shimmery pigments are often made using toxic compounds or pollutive microplastics (SN: 4/15/19). That makes the sparkly stuff, notoriously difficult to clean up in the house, a scourge on the environment too.

A new, nontoxic, biodegradable alternative could change that. In the material, cellulose — the main building block of plant cell walls — creates nanoscale patterns that give rise to vibrant structural colors (SN: 9/28/21). Such a material could be used to make eco-friendly glitter and shiny pigments for paints, cosmetics or packaging, researchers report November 11 in Nature Materials.

The inspiration to harness cellulose came from the African plant Pollia condensata, which produces bright, iridescent blue fruits called marble berries. Tiny patterns of cellulose fibers in the berries’ cell walls reflect specific wavelengths of light to create the signature hue. “I thought, if the plants can make it, we should be able to make it,” says chemist Silvia Vignolini of the University of Cambridge.

Vignolini and colleagues whipped up a watery mixture containing cellulose fibers and poured it onto plastic. As the liquid dried into a film, the rodlike fibers settled into helical structures resembling spiral staircases. Tweaking factors such as the steepness of those staircases changed which wavelengths of light the cellulose arrangements reflected, and therefore the color of the film.

That allowed the researchers, like fairy-tale characters spinning straw into gold, to transform their clear, plant-based slurry into meter-long shimmery ribbons in a rainbow of colors. These swaths could then be peeled off their plastic platform and ground up to make glitter.
“You can use any type of cellulose,” Vignolini says. Her team used cellulose from wood pulp, but could have used fruit peels or cotton fibers left over from textile production.

The researchers need to test the environmental impacts of their newfangled glitter. But Vignolini is optimistic that materials using such natural ingredients have a bright future.