The continuing search for life beyond Earth is driving many of the priorities for what’s next when it comes to U.S. planetary exploration. In a new report that could shape the next 10 years of planetary missions, Mars, Uranus and Saturn’s moon Enceladus have come out on top.

This report is the latest decadal survey for planetary science and astrobiology. Every 10 years, experts convened by the National Academies of Sciences, Engineering and Medicine compile a look at the state of the field and pull together a list of recommended priorities for the next decade of exploration. The new survey, which covers 2023 to 2032, will be used by NASA, the National Science Foundation and others to help guide which projects are pursued and funded.

The survey is meant in part “to identify the key scientific questions that are the most important” to pursue in the next decade and assess how best to answer them, astrophysicist Robin Canup said April 19 during a news conference after the report was released. Canup, of the Southwest Research Institute in Boulder, Colo., is a cochair of the steering committee for the decadal survey.

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At the top of the list, the report recommends continuing the Mars sample-return effort by developing a mission that will retrieve, as soon as possible, the rock and soil samples that NASA’s Perseverance rover is collecting and storing (SN: 9/10/21). This multipart sample-return mission was also the top priority of the previous decadal survey, released in 2011 (SN: 3/7/11). Those samples could hold hints of past signs of life on the Red Planet.

The report also suggests that the next Mars mission, after the sample-return one, should look for signs of life in the ice as well as gaseous biosignatures in the atmosphere. That one is farther down the priority list, though.

Next in the line after the Mars sample-return mission is a large, several-billion-dollar mission to send an orbiter and probe to Uranus to explore the planet, its ring system and its moons. Uranus and the solar system’s other ice giant, Neptune, were visited once, in the late 1980s, when Voyager 2 flew by each.

The time has come to go back, scientists say (SN: 2/10/16). “I’m really thrilled to see that they picked a mission to go back and follow up on those incredible discoveries and those wonderful images that Voyager took,” says planetary scientist Linda Spilker of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who was not involved in the decadal survey. Spilker began her career with Voyager.

What’s more, better understanding the ice giants in our solar system could help scientists decipher the mysteries of faraway worlds. In the hunt for planets outside our solar system, the most common type of known exoplanets are those like Neptune and Uranus.

A mission to Uranus “will be transformative,” says planetary scientist Amy Simon of NASA Goddard Space Flight Center in Greenbelt, Md., and a member of the decadal steering committee. “We’re sure there’s going to be fantastic discoveries.”  

This mission could launch in June 2031 or April 2032, the report suggests. After swinging by Jupiter to use the giant planet’s gravity to fling it faster, the spacecraft would arrive at Uranus 13 years after its launch. Once there, the orbiter would drop a probe in the atmosphere, sampling its composition as never before.

The next highest priority is sending an “orbilander” to Saturn’s moon Enceladus, a world known to have easily accessible liquid water (SN: 5/2/06). NASA’s now-defunct Cassini mission discovered in 2005 that this small moon spews geysers of water into space, and more recent research suggests that water coming from subsurface locales has salts, possibly indicating warm pockets of water interacting with rock — and brewing an environment that may host life (SN: 8/4/14).

Does Enceladus (shown) harbor life? A new planetary science report recommends planning a mission to the Saturnian moon to try to answer that question.JPL-Caltech/NASA, Space Science Institute

This proposed spacecraft would arrive at the moon in the early 2050s, where it would first spend 1.5 years orbiting Enceladus, flying through its watery plumes to sample the liquid. Then the spacecraft would land on the surface for a two-year mission.

“If you want to go and look for life, Enceladus is a very good place to do it,” says planetary scientist Francis Nimmo of the University of California, Santa Cruz, and a member of the decadal steering committee.

Life on other planets isn’t the only thing on planetary scientists’ minds. The report also recommends continuing work on a mission to find and characterize near-Earth objects, like asteroids and comets, in an effort to protect life on the only planet where it’s known to exist.

Two medium-sized missions should be funded in the next decade too, the report recommends. While the survey doesn’t specify targets for these missions, nine higher-priority locales are singled out, including Venus, Saturn’s moon Titan and Neptune’s moon Triton.

The decadal survey also considered the state of the fields of planetary science and astrobiology — namely decreasing funding opportunities and how to improve diversity, equity, inclusion and accessibility efforts. For the latter, the committee looked at whether the community has diverse representation through their members.

“The thing that became abundantly clear is that NASA has done a terrible job of collecting those kinds of statistics,” Nimmo says of demographics in planetary science. For now, the recommendation is to better survey the scientific community, he says.  “We’re not going to be able to solve anything until we actually have better statistics.” More

An ocean’s worth of water may be lurking in minerals below Mars’ surface, which could help explain why the Red Planet dried up.

Once home to lakes and rivers, Mars is now a frigid desert (SN: 12/8/14). Scientists have typically blamed that on Mars’ water wafting out of the planet’s atmosphere into space (SN: 11/12/20). But measurements of atmospheric water loss made by spacecraft like NASA’s MAVEN orbiter are not enough to account for all of Mars’ missing water — which was once so abundant it could have covered the whole planet in a sea up to 1,500 meters deep. That’s more than half the volume of the Atlantic Ocean.

Computer simulations of water moving through Mars’ interior, surface and atmosphere now suggest that most of the Red Planet’s water molecules may have gotten lodged inside the crystal structures of minerals in the planet’s crust, researchers report online March 16 in Science. 

The finding “helps bring focus to a really important mechanism for water loss on Mars,” says Kirsten Siebach, a planetary geologist at Rice University in Houston who was not involved in the work. “Water getting locked up in crustal minerals may be equally important as water loss to space and could potentially be more important.”

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Planetary scientist Eva Scheller of Caltech and colleagues simulated possible scenarios for water loss on Mars, based on observations of the Red Planet made by rovers and orbiting spacecraft, and lab analyses of Martian meteorites. These simulations accounted for possible water loss to space and into the planet’s crust through bodies of water or groundwater interacting with rock.

In order for the simulations to match how much water was on Mars 4 billion years ago, how much is left in polar ice caps today and the observed abundance of hydrogen in Mars’ atmosphere, 30 to 99 percent of Mars’ ancient water must be stashed away inside its crust. The rest was lost to space.

Judging by modern Martian landscapes, like this image taken by the Curiosity rover at the base of Mount Sharp, the Red Planet appears bone dry. But an entire ocean’s worth of water may be lurking underground, in the minerals of the planet’s crust.MSSS/JPL-Caltech/NASA

Water gets locked inside minerals on Earth, too, says Scheller, who presented the results March 16 in a news conference at the virtual Lunar and Planetary Science Conference. But unlike on Mars, that underground water is eventually belched back out into the atmosphere by volcanoes. That difference is important for understanding why one rocky planet may be lush and wet and habitable, while another is an arid wasteland. 

Mars’ underground water could be mined by future explorers, says Jack Mustard, a planetary geologist at Brown University in Providence, R.I., not involved in the work. The most easily accessible water on Mars may be at its polar ice caps (SN: 9/28/20). But “to get the ice, you’ve got to go up to [high latitudes] — kind of cold, harder to live there,” Mustard says. If water can be extracted from minerals, it could support human colonies at warmer climes closer to the equator.  More

The James Webb Space Telescope has spotted objects in the early universe that might be a new kind of star — one powered by dark matter.

These “dark stars” are still hypothetical. Their identification in JWST images is far from certain. But if any of the three candidates — reported in the July 25 Proceedings of the National Academy of Sciences — turn out to be this new type of star, they could offer a glimpse of star formation in the early universe, hint at the nature of dark matter and possibly explain the origins of supermassive black holes.

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First proposed in 2007 by cosmologist Katherine Freese and colleagues, dark stars might have been some of the first types of stars to form in the universe (SN: 1/1/08). Though dark stars have yet to be observed, they’re thought to be powered by heat from dark matter interactions rather than by nuclear fusion reactions like in the sun.

Dark stars “would be very weird looking,” says Freese, of the University of Texas at Austin. The hypothetical stars would have formed from clouds of hydrogen and helium that drew in locally abundant dark matter as they coalesced. Though the true nature of dark matter isn’t known — its presence is inferred largely via its effect on how stars move within galaxies — it’s possible that dark matter particles can interact with themselves, annihilating each other when they collide and producing vast amounts of light and heat (SN: 7/7/22). That heat would keep the cloud of hydrogen and helium from condensing into a dense, hot core like the stars that exist today.

Because the heat from dark matter annihilations would keep the gas cloud from condensing, dark stars could grow to gargantuan size. Theoretically, dark stars could be 10 times as wide as Earth’s orbit around the sun. They could also be millions of times as massive as the sun and shine billions of times brighter — bright enough, potentially, to be spotted by JWST.

To see if any dark stars are lurking in data from the orbiting observatory, Freese and colleagues pored over images from a JWST survey of early galaxies. In such images, JWST has so far discovered over 700 objects that may have originated in the first few hundred million years of the universe — the epoch when dark stars would have emerged (SN: 12/16/22). Light from these remote objects is stretched, or redshifted, as the universe expands. So Freese and colleagues zeroed in on four objects already confirmed to be highly redshifted, making them some of the oldest objects seen to date.

Those objects are currently thought to be small galaxies from the universe’s relative infancy. But because they’re so far away, JWST can’t resolve them well enough to determine whether they’re actually galaxies or large, ultrabright stars, the researchers say.

Three dark star candidates were identified from data collected by the JWST Advanced Deep Extragalactic Survey. One of the candidates, JADES-GS-z13-0, is shown here (arrow).NASA, ESA, CSA, JADES Collaboration

The team ran computer simulations of how much light a hypothetical dark star might produce at various wavelengths. They compared those spectra to light from images collected by JWST at different wavelengths for each of the four objects. JWST data from three of those objects are consistent with the simulated dark star patterns, Freese and colleagues report.

Some scientists are skeptical. Known types of stars could also create the observed light from the three candidates, says Sandro Tacchella, an astrophysicist at the University of Cambridge. And identifying any of the objects as a dark star would require that the simulated patterns fit well to more detailed spectra, says Brant Robertson, a theoretical astrophysicist at the University of California, Santa Cruz.

If dark stars were to be found, though, “that would be revolutionary,” says study coauthor Cosmin Ilie, an astrophysicist at Colgate University in Hamilton, N.Y.

Detecting dark stars would confirm the existence of a dark matter particle and hint at how it works (SN: 7/7/22). “Just having the information that [dark matter] is something that could annihilate would be really, really powerful,” says Tracy Slatyer, a theoretical physicist at MIT who was not involved in the study. That knowledge could help scientists look for dark matter elsewhere in the universe, she says.

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Dark stars could also help explain the formation of supermassive black holes (SN: 3/16/18). Once the dark matter inside the star has annihilated itself, the remaining hydrogen and helium — millions of times the mass of the sun in a relatively compact space — would collapse in on itself and form a black hole. Those black holes could merge over time into black holes like the ones at the centers of most galaxies, millions or billions of times as massive as the sun.

Future experiments, like looking for brighter or dimmer light at certain wavelengths, could help confirm whether any of the three objects are dark stars. Freese also expects to find more dark star candidates in future JWST data, she says. But for now, whether dark stars truly exist remains a mystery. More

Maybe hold off on that Martian ice fishing trip. Two new studies splash cold water on the idea that potentially habitable lakes of liquid water exist deep under the Red Planet’s southern polar ice cap.

The possibility of a lake roughly 20 kilometers across was first raised in 2018, when the European Space Agency’s Mars Express spacecraft probed the planet’s southern polar cap with its Mars Advanced Radar for Subsurface and Ionosphere Sounding, or MARSIS, instrument. The orbiter detected bright spots on radar measurements, hinting at a large body of liquid water beneath 1.5 kilometers of solid ice that could be an abode to living organisms (SN: 7/25/18). Subsequent work found hints of additional pools surrounding the main lake basin (SN: 9/28/20).

But the planetary science community has always held some skepticism over the lakes’ existence, which would require some kind of continuous geothermal heating to maintain subglacial conditions (SN: 2/19/19). Below the ice, temperatures average –68° Celsius, far past the freezing point of water, even if the lakes are a brine containing a healthy amount of salt, which lowers water’s freezing point. An underground magma pool would be needed to keep the area liquid — an unlikely scenario given Mars’ lack of present-day volcanism.

“If it’s not liquid water, is there something else that could explain the bright radar reflections we’re seeing?” asks planetary scientist Carver Bierson of Arizona State University in Tempe.

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In a study published in the July 16 Geophysical Research Letters, Bierson and colleagues describe a couple other substances that could explain the reflections. Radar’s reflectivity depends on the electrical conductivity of the material the radar signal moves through. Liquid water has a fairly distinctive radar signature, but examining the electrical properties of both clay minerals and frozen brine revealed those materials could mimic this signal.

Adding weight to the non-lake explanation is a study from an independent team, published in the same issue of Geophysical Research Letters. The initial 2018 watery findings were based on MARSIS data focused on a small section of the southern ice cap, but the instrument has now built up three-dimensional maps of the entire south pole, where hundreds to thousands of additional bright spots appear.

“We find them literally all over the region,” says planetary scientist Aditya Khuller, also of Arizona State University. “These signatures aren’t unique. We see them in places where we expect it to be really cold.”

Creating plausible scenarios to maintain liquid water in all of these locations would be a tough exercise. Both Khuller and Bierson think it is far more likely that MARSIS is pointing to some kind of widespread geophysical process that created minerals or frozen brines.

While previous work had already raised doubts about the lake interpretation, these additional data points might represent the pools’ death knell. “Putting these two papers together with the other existing literature, I would say this puts us at 85 percent confidence that this is not a lake,” says Edgard Rivera-Valentín, a planetary scientist at the Lunar and Planetary Institute in Houston who was not involved in either study.

The lakes, if they do exist, would likely be extremely cold and contain as much as 50 percent salt — conditions in which no known organisms on Earth can survive. Given that, the pools wouldn’t make particularly strong astrobiological targets anyway, Rivera-Valentín says. (SN: 5/11/20).

Lab work exploring how substances react to conditions at Mars’ southern polar ice cap could help further constrain what generates the bright radar spots, Bierson says.

In the meantime, Khuller already has his eye on other areas of potential habitability on the Red Planet, such as warmer midlatitude regions where satellites have seen evidence of ice melting in the sun. “I think there are places where liquid water could be on Mars today,” he says. “But I don’t think it’s at the south pole.”  More

It started with a spring breeze. The Opportunity rover watched with its robotic eyes as the wind blowing through Perseverance Valley kicked puffs of rusty Mars dust into the air. In more than 14 Earth years of exploring the Red Planet, the rover had seen plenty of this kind of weather.
But the dust grew thicker. Small flecks swirled like wildfire smoke through the atmosphere, turning sun-filled midday into dusk, then night. Within a week, the dust storm spanned more than twice the area of the contiguous United States and eventually encircled the whole planet, allowing just 5 percent of the normal amount of light to reach Opportunity’s solar panels. The rover went quiet.
“It got so bad so quickly, we didn’t even have time to react,” says Keri Bean of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. Bean had joined Opportunity’s rover-operating team just before that May 2018 storm.
Dust storms like that one, which snuffed out Opportunity for good, are the most dramatic and least predictable events on the Red Planet (SN: 3/16/19, p. 7). Such storms can make the nail-biting process of landing on Mars even more dangerous and could certainly make life difficult for future human explorers.

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Despite almost 50 years of study, scientists are missing some key data that would help explain how dust gets kicked into the air to form planet-wide storms and what keeps it circulating for weeks or months at a time.
“We just do not understand how dust storms form on Mars,” says planetary meteorologist Scott Guzewich of NASA’s Goddard Space Flight Center in Greenbelt, Md. History has shown that certain regions and seasons are more prone to dust than others. “Other than that, we’re … blind.”
Mars missions set to launch this summer, from the United States, China and the United Arab Emirates, will help solve that pressing mystery. NASA’s new rover, Perseverance, will carry a suite of weather sensors called MEDA, for Mars Environmental Dynamics Analyzer. Those sensors will build on decades of Mars exploration and fill in missing puzzle pieces.
“Predicting dust is the ultimate goal” for MEDA, says planetary scientist Germán Martínez of the Lunar and Planetary Institute in Houston. The data MEDA will collect will be “the most substantial contribution to this topic so far.”
Dust, dust everywhere
Dust is as important to weather on Mars as water is on Earth. With no oceans, scant water vapor and a thin atmosphere, Martian weather can be monotonously calm for about half the Martian year, which lasts close to 687 Earth days. But when the Red Planet’s orbit brings it closer to the sun, dust storm season begins.
In the 10-month dusty season, which corresponds to spring and summer in the southern hemisphere, extra sunlight warms the atmosphere. That warmth generates strong winds as air moves from warm to cool regions. Those winds lift more dust, which absorbs sunlight and warms the atmosphere, generating still stronger winds, which lift even more dust.

The storms come in a range of sizes: Local storms can cover an area about the size of Alaska and last up to three Martian days (each of which lasts about 24.5 hours); global storms can engulf the planet for months. The storm that defeated Opportunity raged from the end of May through late July. Such global storms probably result when several smaller storms merge.
Global dust storms have affected Mars exploration since the arrival of the first long-term robotic visitor in 1971, when NASA’s Mariner 9 orbiter found the planet’s surface entirely obscured. Opportunity and its twin rover, Spirit, both survived a global dust storm in 2007, yet a large regional dust storm ended the Phoenix lander’s mission in 2008.
There has never been a Mars mission that didn’t worry about dust.
A farmer’s almanac
Luckily, Mariner 9 was an orbiter, with no plans to land. It just had to wait for the skies to clear to start snapping pictures of the Martian surface. But the same 1971 storm is probably to blame for vanquishing two Soviet landers that arrived at almost the same time.
Spacecraft that must land to do their work can’t just wait for better timing. Launch windows for missions between Earth and Mars open only every 26 months or so. Engineers who design landing systems need to know what conditions a spacecraft will face when it gets there, says Allen Chen of the Jet Propulsion Lab, who leads the entry, descent and landing for Perseverance.
The most important factor is the density of the atmosphere. Even though Mars’ atmosphere exerts just 1 percent of the pressure of Earth’s on the planet’s surface, both the thin Martian air and the wind blowing through it slow down the spacecraft and affect where it lands, Chen says.
Perseverance will take pictures of the ground while parachuting through the atmosphere and match the images to an onboard map made with images from NASA’s Mars Reconnaissance Orbiter. Based on those details, an in-flight navigation system will steer the rover to a safe landing spot, helping the rover touch down within an area 25 kilometers wide — the most precise Mars landing ever.
“But that’s dependent on being able to see the ground,” Chen says, without dust obscuring the view.
To land a rover, engineers like Chen rely on forecasts that use the past to tell the future — ​similar to weather forecasts on Earth, but with less data. Atmospheric scientist Bruce Cantor of Malin Space Science Systems in San Diego, a self-described Mars weatherman, put out a Mars weather report every week until September 2019. His forecasts are based on statistics and historical data, mostly taken from orbit. “It’s almost like a farmer’s almanac in my head,” he says.
Cantor’s forecasts for Mars landings since 1999 have been “pretty accurate,” he says, and he boasts that he predicted the storm that ended the Phoenix mission to within three days. More accuracy wouldn’t have saved Phoenix, he says. The lander’s batteries were already low from low winter sunlight levels and the buildup of dust on the solar panels. “It was just a matter of what storm was going to be the mission-ending one,” he says.
He foresees clear skies for Perseverance’s touchdown in February 2021. Based on the season and weather patterns in the past, the probability of a dust storm hitting within 1,000 kilometers of the center of Perseverance’s landing area is less than 2 percent, Cantor and colleagues reported in the journal Icarus in March 2019.
But just in case, Chen’s team trained the navigation system to “deal with it being pretty darn dusty,” Chen says.
A constellation of weather stations
As Mars missions get more complex, and especially as NASA and other groups contemplate sending human explorers, being able to prepare for dust storms takes on extra urgency.
“Someday, somebody is going to go to Mars, and they’re going to want to know when and where storms occur,” Cantor says. “That’s when this stuff becomes really important.”
Cantor would know. Well over a decade ago, while testing a different rover system in Southern California, he jumped into a 2-meter-tall dust devil just to see what it would feel like. “Not one of my smartest moves,” he says. He wasn’t injured, but “it did not feel good. It felt like getting sandblasted.”
Martian astronauts would be protected by more than shorts and a T-shirt, but dust could easily invade human habitats and clog air filters — or damage astronauts’ lungs if they breathe it in. The dust may even carry poisonous and carcinogenic materials that could make astronauts ill over the course of a mission.
Astronauts will need to know when to stay inside. Part of the problem in predicting storms is a sheer lack of data. For Earth’s weather, meteorologists use thousands of ground-based weather stations, plus data from satellites, balloons and airplanes. Mars has only six active satellites, run by NASA and the European and Indian space agencies. And just two sets of weather instruments report from Mars’ surface: one on the Curiosity rover, which has been collecting data since 2012 (SN: 5/2/15, p. 24), and a nearly identical set that arrived with the InSight lander in 2018.

But those two spacecraft are practically neighbors, a big weakness for understanding the whole planet. “It’d be like having one of your weather stations in D.C. and the other in Buffalo,” Guzewich says.
Perseverance will help fill in the gaps. So might China’s first Mars rover, Tianwen-1, set to launch in July with an instrument to measure air temperature, pressure and wind. The Russian and European ExoMars mission, scheduled to launch in 2022, includes a lander called Kazachok equipped with meteorology and dust sensors (SN Online: 3/12/20).
From the air, the UAE’s Emirates Mars Mission, known as Hope, will observe weather, including storms, and how the atmosphere interacts with the ground. Over one Martian year in orbit, Hope will help build a global picture of how the atmosphere changes day to day and between the seasons.
Just having a few more weather stations will be a big boost, says José A. Rodríguez Manfredi of the Center for Astrobiology in Madrid, principal investigator for MEDA, the weather sensors on Perseverance. “We will have a mini network working on Mars in a few years.”
But four or five weather stations on the ground probably won’t be enough. To reliably predict dust storms, what Mars scientists need is a global network collecting data all the time.
To cut down on the cost of such a network, Guzewich suggests figuring out which measurements “would give us the most bang for our buck.” For Earth, NASA and other agencies use a type of study called an Observing System Simulation Experiment to figure out which variables are most important for predicting the weather. Satellites are then designed to focus on those most valuable observations. Such a study has never been done for Mars, but the only obstacle is funding, Guzewich says.
“Mars atmospheric scientists have been clamoring” for such experiments, he says. “We’re not going to reproduce Earth’s observing network before humans go to Mars. It’s not going to happen…. But maybe we could do something that is financially and technologically reasonable that really does make a difference and gets us to the point where we can predict the future a couple days in advance.”
China’s space agency plans to launch its first Mars mission, called Tianwen-1, in July. Its rover (illustrated atop the lander) will measure air temperature, pressure and wind, among other things.Xinhua
Blowing in the wind
Mars forecasts also suffer from a lack of fundamental information, Martínez says. How hard does the wind have to blow to lift the dust? And what does the dust do once it’s airborne?
This is where Perseverance will shine. The rover will make the best direct measurements yet of wind speed and direction on Mars, especially the vertical wind that lifts dust upward.
For a long time, scientists struggled to understand how dust was lifted into the air at all. “It seemed like it couldn’t be possible,” Guzewich says. “The atmosphere is so thin, a single particle of dust or sand is so heavy, it just shouldn’t work.” Observations and experiments over the last 20 years suggest that once sand grains start bouncing along the surface, they can knock into other grains and knock smaller particles upward. But it’s still not possible to tell which of those bouncing grains will lead to a storm — or which of those storms will go global.
Mars climatologists have tried to make detailed wind measurements for decades, Martínez says, but have hit several stretches of bad luck. Only five surface missions — the Viking 1 and 2 landers in 1976, the Pathfinder lander in 1997 and the ongoing Curiosity and InSight missions — have provided useful data on wind speed and direction near the surface. And even those have had mixed results.
NASA’s InSight lander, shown here in a mosaic of selfies the spacecraft took, carries a set of weather sensors called TWINS, or Temperature and Wind for InSight. The lander is one of just two weather stations on the Martian surface. Mars atmospheric scientists say they need more to predict dangerous dust storms.JPL-Caltech/NASA
“Arguably, the best wind record on Mars is still the one from the Vikings, 40 years ago,” Martínez says. Curiosity was supposed to take direct wind measurements in all directions with a pair of electrically heated booms that jutted away from the rover’s neck. “We had great expectations,” Martínez says.
But photos the rover took of itself showed that one boom was damaged as the rover landed, and out of commission. For the first 1,490 Martian days of Curiosity’s mission, the rover could take measurements only when the wind was blowing head on. Then, in October 2016, the second boom broke. In April, researchers suggested a way to hack Curiosity’s temperature sensors to get wind data, but there’s no plan to use that hack at the moment, Guzewich says.
That leaves InSight, but its wind readings are muddled by other parts of the lander getting in the way of airflow. The readings are still useful, but the MEDA team hopes to do better.
Taking lessons from InSight and Curiosity, Perseverance’s MEDA will have more wind sensors that reach farther from the rover’s body. The sensors will be protected by a shield until after the rover has landed safely.
“We are very excited,” Martínez says. “The vertical wind has never been measured before on Mars. We’re going to do that.”
Measuring wind speeds will help scientists determine how hard the wind must blow to kick up dust, the first step in triggering a dust storm.
That figure has personal resonance for Bean, the former Opportunity rover operator. Her first shift was exactly two weeks before the mission-ending global dust storm. She told the rover to use its arm to brush the surface of a rock.
“My coworkers blamed me for starting a whole butterfly effect,” she says. “You brushed the surface,” they joked, “the dust went up, you started the whole dust storm.”
In its end-of-mission report, the Opportunity team admits it will never really know what ended Opportunity’s nearly 15-year run. One possibility is that the dust grew too thick on the solar panels for gentle wind in the calm season to blow the dust off.
One potential fix would be to design future rovers to vibrate their solar panels fast enough to make dust skitter off, Bean says. Once humans are on the planet, they could just clear dust with their arms.
A week or so before Opportunity was officially declared lost, Bean decided to memorialize the rover. “I’d always liked tattoos, but nothing ever spoke to me,” she says. In college, she had studied Mars’ atmospheric opacity — the amount of light that can penetrate an atmosphere’s dust, represented by the Greek letter τ. So Bean got a tattoo on her arm of the last measurement Opportunity sent to Earth: “τ=10.8.” That stands for a night-dark sky in the middle of the day.

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