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    Here’s how to watch NASA’s Perseverance lander touch down on Mars

    All eyes are on Mars — and all ears, too. When NASA’s Perseverance rover touches down on the Red Planet on February 18, the landing will be recorded with sight, sound and maybe even touch.
    The rover will cap off a month of Mars arrivals from space agencies around the world (SN: 7/30/20). Perseverance joins Hope, the first interplanetary mission from the United Arab Emirates, which successfully entered Mars orbit on February 9; and Tianwen-1, China’s first Mars mission, which arrived on February 10 and will deploy a rover to the Martian surface in May.
    NASA will broadcast Perseverance’s landing on YouTube starting at 2:15 p.m. EST. The actual moment of touchdown is expected at approximately 3:55 p.m. EST. Perseverance is designed to explore an ancient river delta called Jezero crater, searching for signs of ancient life and collecting rocks for a future mission to return to Earth (SN: 7/28/20).
    The rover will use the landing system pioneered by its predecessor, Curiosity, which has been exploring Mars since 2012 (SN: 8/6/12). But in a first for Mars touchdowns, this rover will record its own landing with dedicated cameras and a microphone.
    As the craft carrying Perseverance zooms through the thin Martian atmosphere, three cameras will look up at the parachute slowing it down from supersonic speeds. When a rocket-powered “sky crane” platform lowers the rover to the ground, a fourth camera on the platform will record the rover’s descent. Another camera on the rover will look back up at the platform, and a sixth camera will look at the ground.
    Perseverance will use the “sky crane” landing system pioneered by its predecessor, Curiosity. The landing involves dangling the rover from a floating platform on cables and touching down directly on its wheels.JPL-Caltech/NASA
    Perseverance will use the “sky crane” landing system pioneered by its predecessor, Curiosity. The landing involves dangling the rover from a floating platform on cables and touching down directly on its wheels.JPL-Caltech/NASA
    “The goal is to see the video and the action of getting from high up in the atmosphere down to the surface,” says engineer David Gruel of NASA’s Jet Propulsion Laboratory in Pasadena, who was the engineering lead for that six-camera system, called EDL-Cam. He hopes every engineer on the team has an image of the rover hanging below the descent stage as their computer desktop background six months from now.
    Because it will take more than 11 minutes for signals to travel between Earth and Mars, the cameras won’t stream the landing movie in real time. And after Perseverance lands, engineers will be focused on making sure the rover is healthy and able to collect science data, so the landing videos won’t be among the first data sent back. Gruel expects to be able to share what the rover saw four days after landing, on February 22.

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    Perseverance will also carry microphones to record first-ever audio of a Mars landing. Unlike the landing cameras, the microphones will continue to work after touchdown, hopefully helping the engineering team keep track of the rover’s health. Motors sound different when they get clogged with dust, for instance, Gruel says. The team will hear the sound of the rover’s wheels crunching across the Martian surface, and maybe the sound of the wind blowing.
    “Are we going to hear a dust devil? What might a dust devil sound like? Could we hear rocks rolling down a hill?” Gruel asks. “You never know what we might stumble onto.”
    Sound will add a way to share Mars with people who have trouble seeing, Gruel notes. “It might appeal to a whole other element of the population who might not have been able to experience past missions the same way,” he says.
    [embedded content]
    Watch NASA’s live coverage of the Perseverance landing here starting at 2:15 p.m. EST.
    Elsewhere on Mars, the InSight lander will be listening to the landing too (SN: 2/24/20). The lander’s seismometer may be able to feel vibrations when two tungsten weights that Perseverance carried to Mars for stability smack into the ground before the rover lands, geophysicist Benjamin Fernando of the University of Oxford and colleagues report in a paper posted December 3 to eartharxiv.org and submitted to JGR Planets.
    “No one’s ever tried to do this before,” Fernando says.
    The ground will move by at most 0.1 nanometers per second, Fernando and colleagues calculated. “It’s incredibly small,” he says. “But the seismometer is also incredibly sensitive.”
    The team may be able to catch that tiny signal because they know exactly when and where the impact will happen. If the lander does pick up the signal, it will tell scientists something about how fast seismic waves travel through the ground, a clue to the details of Mars’ interior structure. And even if they don’t feel anything, that will put limits on the waves’ speed. “It still teaches us something,” Fernando says.
    The InSight team hopes to also feel vibrations from Tianwen-1 when its rover touches down in May. “Detecting one would be great,” Fernando says. “Detecting two would be like, amazing.” More

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    Fossil mimics may be more common in ancient rocks than actual fossils

    When it comes to finding fossils of very ancient microbial life — whether on Earth or on other worlds, such as Mars — the odds are just not in our favor.
    Actual microbial life-forms are much less likely to become safely fossilized in rocks compared with nonbiological structures that happen to mimic their shapes, new research finds. The finding suggests that Earth’s earliest rocks may contain abundant tiny fakers — minuscule objects masquerading as fossilized evidence of early life — researchers report online January 28 in Geology.
    The finding is “at the very least a cautionary tale,” says study author Julie Cosmidis, a geomicrobiologist at the University of Oxford.
    Tiny, often enigmatic structures found in some of Earth’s oldest rocks, dating back to more than 2.5 billion years, can offer tantalizing hints of the planet’s earliest life. And the hunt for ever-more-ancient signs of life on Earth has sparked intense debate — in part because the farther back in time you go, the harder it is to interpret tiny squiggles, filaments and spheres in the rock (SN: 1/3/20). One reason is that the movements of Earth’s tectonic plates over time can squeeze and cook the rocks, deforming and chemically altering tiny fossils, perhaps beyond recognition.

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    But an even more pernicious and contentious problem is that such tiny filaments or spheres may not be biological in origin at all. Increasingly, scientists have found that nonbiological chemical processes can create similar shapes, suggesting the possibility of “false positives” in the biological record.
    One such discovery led to the new study, Cosmidis says. A few years ago, she and others were trying to grow bacteria and make them produce sulfur. “We were mixing sulfides with organic matter, and we started forming these objects,” she says. “We thought they were formed by the bacteria, because they looked so biological. But then we realized they were forming in laboratory tubes that happened to have no bacteria in them at all.”
    That led her to wonder about such processes happening in the rocks themselves. So she and others decided to examine what would happen if they tried to re-create the early formation stages of chert, a kind of compact, silica-rich rock common on the early Earth. “Microfossils are often found in chert formations,” says study coauthor Christine Nims, a geobiologist now at the University of Michigan in Ann Arbor. “Anything hosted in [chert] will be well-preserved.”
    Chert forms out of silica-rich water; the silica precipitates out of the water and accumulates, eventually hardening into rock. Cosmidis, Nims and colleagues added sulfur-containing bacteria called Thiothrix to solidifying chert to see what might happen during actual fossilization. To other chert samples, they added sulfur-containing “biomorphs,” spheres and filaments made of tiny crystals but shaped like bacteria.
    At first, nanoparticles of silica encrusted the bacteria and the biomorphs, Nims says. But after a week or so, the bacteria started to deform, their cells deflating from cylinders into flattened, unrecognizable ribbons as the sulfur inside the cells diffused out and reacted with the silica outside the cells, forming new minerals.
    The biomorphs, on the other hand, “had this impressive resiliency,” she says. Although they, too, lost sulfur to the surrounding solution, they kept their silica crust. As a result, “they kept their shape and showed very little change over time.” That endurance suggests that enigmatic structures found in the early rock record have a better chance of being pseudofossils, rather than actual fossils, the team says.
    In a new study, researchers produced twisted filament-shaped biomorphs (top) from the reactions of sulfide with prebiotic organic compounds. The biomorphs resemble possible microbial fossils (bottom, filaments indicated by red arrows) found in rocks dating to 3.5 billion years ago.From top: C. Nims; R.J. Baumgartner et al/Geology 2019
    The idea that once-living creatures are harder to preserve makes sense, says Sean McMahon, an astrobiologist at the University of Edinburgh who was not involved in the new study. “It’s not totally surprising,” he says. “We know that biomass does tend to break down quite quickly.”
    In fact, scientists have known for centuries that certain chemical reactions can act as “gardens” that “grow” strange-shaped mineral objects, twisting into tubes or sprouting branches or otherwise mimicking the weirdness of life. “There’s a complacency about it, a misconception that we kind of know all this and it’s already been dealt with,” McMahon says.
    Strategies to deal with this conundrum have included looking for particular structures — such as mound-shaped stromatolites — or chemical compounds in a potential fossil that are thought to be uniquely formed or modified by the presence of life (SN: 10/17/18). Those criteria are the product of decades of field studies, through which scientists have amassed a vast reference dataset of fossil structures, against which researchers can compare and evaluate any new discoveries.
    “Anything we find, we can look at through that lens,” McMahon says. But what’s lacking is a similarly rich dataset for how such structures might form in the absence of life. This study, he says, highlights that attempts “to define criteria for recognizing true fossils in very ancient rocks are premature, because we don’t yet know enough about how nonbiological processes mimic true fossils.”
    It’s an increasingly urgent problem with rising stakes, as NASA’s Perseverance rover is about to set down on Mars to begin a new search for traces of life in ancient rocks (SN: 7/28/20), he adds. “Paleontologists and Mars exploration scientists should take [this study] very seriously.” More

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    How future spacecraft might handle tricky landings on Venus or Europa

    The best way to know a world is to touch it. Scientists have observed the planets and moons in our solar system for centuries, and have flown spacecraft past the orbs for decades. But to really understand these worlds, researchers need to get their hands dirty — or at least a spacecraft’s landing pads.
    Since the dawn of the space age, Mars and the moon have gotten almost all the lander love. Only a handful of spacecraft have landed on Venus, our other nearest neighbor world, and none have touched down on Europa, an icy moon of Jupiter thought to be one of the best places in the solar system to look for present-day life (SN: 5/2/14).
    Researchers are working to change that. In several talks at the virtual American Geophysical Union meeting that ran from December 1 to December 17, planetary scientists and engineers discussed new tricks that hypothetical future spacecraft may need to land on unfamiliar terrain on Venus and Europa. The missions are still in a design phase and are not on NASA’s launch schedule, but scientists want to be prepared.

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    Navigating a Venusian gauntlet
    Venus is a notoriously difficult world to visit (SN: 2/13/18). Its searing temperatures and crushing atmospheric pressure have destroyed every spacecraft lucky enough to reach the surface within about two hours of arrival. The last landing was over 30 years ago, despite increasing confidence among planetary scientists that Venus’ surface was once habitable (SN: 8/26/16). That possibility of past, and perhaps current, life on Venus is one reason scientists are anxious to get back (SN: 10/28/20).
    In one of the proposed plans discussed at the AGU meeting, scientists have ridged, folded mountainous terrain on Venus called tessera in their sights. “Safely landing in tessera terrain is absolutely necessary to satisfy our science objectives,” said planetary scientist Joshua Knicely of the University of Alaska Fairbanks in a talk recorded for the meeting. “We have to do it.”
    Knicely is part of a study led by geologist Martha Gilmore of Wesleyan University in Middletown, Conn., to design a hypothetical mission to Venus that could launch in the 2030s. The mission would include three orbiters, an aerobot to float in the clouds and a lander that could drill and analyze samples of tessera rocks. This terrain is thought to have formed where edges of continents slid over and under each other long ago, bringing new rock up to the surface in what might have been some version of plate tectonics. On Earth, this sort of resurfacing may have been important in making the planet hospitable to life (SN: 4/22/20).
    Ridged, folded mountainous terrain on Venus called tessera (bright region in this false-color image from NASA’s Magellan spacecraft) might have formed through long-ago tectonic activity.JPL-Caltech/NASA
    But landing in these areas on Venus could be especially difficult. Unfortunately, the best maps of the planet — from NASA’s Magellan orbiter in the 1990s — can’t tell engineers how steep the slopes are in tessera terrain. Those maps suggest that most are less than 30 degrees, which the lander could handle with four telescoping legs. But some could be up to 60 degrees, leaving the spacecraft vulnerable to toppling over.
    “We have a very poor understanding of what the surface is like,” Gilmore said in a talk recorded for the meeting. “What’s the boulder size? What’s the rock size distribution? Is it fluffy?”
    So the lander will need some kind of intelligent navigation system to pick out the best places to land and steer there. But that need for steering brings up another problem: Unlike landers on Mars, a Venus lander can’t use small rocket engines to slow down as it descends.
    The shape of a rocket is tailored to the density of air that it will push against. That’s why rockets that launch spacecraft from Earth have two sections: one for Earth’s atmosphere and one for the near-vacuum of space. Venus’ atmosphere changes density and pressure so quickly between space and the planet’s surface that “dropping a kilometer would go from the rocket working perfectly, to it’s going to misfire and possibly blow itself apart,” Knicely says.
    Instead of rockets, the proposed lander would use fans to push itself around, almost like a submarine, turning the disadvantage of the dense atmosphere into an advantage.
    The planet’s atmosphere also presents the biggest challenge of all: seeing the ground. Venus’ dense atmosphere scatters light more than Earth’s or Mars’ does, blurring the view of the surface until the last few kilometers of descent.
    Worse, the scattered light makes it seem like illumination is coming from all directions at once, like shining a flashlight into fog. There are no shadows to help show steep slopes or reveal big boulders that the lander could crash into. That’s a major issue, according to Knicely, because all of the existing navigation software assumes that light comes from just one direction.
    “If we can’t see the ground, we can’t find out where the safe stuff is,” Knicely says. “And we also can’t find out where the science is.” While proposed solutions to the other challenges of landing on Venus are close to doable, he says, this one remains the biggest hurdle.
    Sticking the landing on Europa
    Jupiter’s icy moon Europa, on the other hand, has no air to blur the surface or break rockets. A hypothetical future Europa lander, also discussed at the AGU meeting, would be able to use the “sky crane” technique (SN: 8/6/12). That method, in which a platform hovers above the surface using rockets and drops a spacecraft to the ground, was used to land the Curiosity rover on Mars in 2012 and will be used for the Perseverance lander in February 2021.
    “The engineers are very excited about not having to deal with an atmosphere on the way down,” said spacecraft engineer Jo Pitesky of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., in a recorded talk for the meeting.
    Still, there’s a lot that scientists don’t know about Europa’s surface, which could have implications for any lander that touches down, said planetary scientist Marissa Cameron of the Jet Propulsion Laboratory in another talk.
    The best views of the moon’s landscape are from the Galileo orbiter in the 1990s, and the smallest features it could see were half a kilometer across. Some scientists have suggested that Europa could sport jagged ice spikes called penitentes, similar to ice features in the Chilean Andes Mountains that are named for their resemblance to hooded monks with bowed heads — although more recent work shows Europa’s lack of atmosphere should keep penitentes from forming.
    Another mission, the Europa Clipper, that’s already underway will take higher-resolution images when the orbiter visits the Jovian moon later this decade, which should help clarify the issue.
    In the meantime, scientists and engineers are running elaborate dress rehearsals for a Europa landing, from simulating ices with different chemical compositions in vacuum chambers to dropping a dummy lander named Olaf from a crane to see how it holds up.
    “We have a requirement that says the terrain can have any configuration — jagged, potholes, you name it — and we have to be able to conform to that surface and be stable at it,” says John Gallon, an engineer at the Jet Propulsion Laboratory. (The dummy lander was named for his 4-year-old daughter’s favorite character in the movie Frozen.)
    [embedded content]
    Olaf, a scale model of a possible Europa lander, is helping NASA engineers test different strategies for landing on the icy moon of Jupiter. The rover is named for the snowman in the movie Frozen.
    Over the last two years, Gallon and colleagues have tested different lander feet, legs and configurations in a lab by suspending the lander from the ceiling like a marionette. That suspension helps simulate Europa’s gravity, which is one-seventh that of Earth’s.
    Without much gravity, a massive lander could easily bounce around and damage itself when trying to land. “You’re not going to stick the landing like a gymnast coming off the bars,” Gallon says. His team has tried sticky feet, bowl-shaped feet, springs that compress and push into the surface and legs that lock to help the lander stay put on various terrains. The lander might crouch like a frog or stand stiff like a table, depending on what type of surface it lands on.
    Although Olaf is hard at work helping scientists figure out what it will take to build a successful Europa lander, the mission itself, like its Venusian counterpart, remains only on some planetary scientists’ wish lists for now. Meanwhile, other researchers dream about voyages to entirely different worlds, including Saturn’s geyser moon Enceladus.
    “Some people will pick favorites,” Cameron says. “I just want to land someplace we’ve never been to that’s not Mars. I’d love that.” More

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    Hayabusa2’s asteroid dirt may hold clues to the early solar system

    For the first time, scientists are about to get their (carefully gloved) hands on asteroid dirt so old it may contain clues to how our solar system formed and how water got to Earth.
    A capsule containing two smidgens of dirt from asteroid Ryugu arrived in Japan on December 7, where researchers will finally get a chance to measure how much was collected. The goal of Japan’s Hayabusa2 mission was to collect at least 100 milligrams of both surface and subsurface material, and send it back to Earth.
    “Hayabusa2 is home,” said project manager Yuichi Tsuda of the Japanese Aerospace Exploration Agency, or JAXA, at a news conference December 6, hours after the sample return capsule landed successfully in Woomera, Australia. “We collected the treasure box.”
    Ryugu is an ancient, carbon-rich asteroid with the texture of freeze-dried coffee (SN: 3/16/20). Planetary scientists think it contains some of the earliest solids to form in the solar system, making it a time capsule of solar system history.
    Hayabusa2 explored Ryugu from June 2018 to November 2019, and grabbed two samples of the asteroid (SN: 2/22/19). One came from inside an artificial crater that Hayabusa2 blasted into the asteroid’s surface, giving the spacecraft access to the asteroid’s interior (SN: 4/5/19). On December 4, the spacecraft released the sample return capsule from about 220,000 kilometers above Earth’s surface. The capsule created a brilliant fireball as it streaked through Earth’s atmosphere.
    The sample return capsule left a brilliant fireball as it blazed through Earth’s atmosphere, but its heat shield prevented it from disintegrating.JAXA
    At a “quick look facility” in Woomera, gases the asteroid material may have emitted were initially analyzed. But the capsule won’t be opened until after it reaches the JAXA center in Sagamihara, Japan.
    Hayabusa2 is the second mission to successfully return an asteroid sample to Earth. The first Hayabusa mission visited stony asteroid Itokawa and returned to Earth in 2010. Engineering and logistical problems meant that its return was years later than planned, and it grabbed only 1,534 grains of asteroid material (SN: 6/14/10).
    For Hayabusa2, though, everything seems to have gone according to plan. The spacecraft itself still has enough fuel to visit another asteroid, 1998 KY26, which is smaller and spins faster than Ryugu. It will study how such asteroids might have formed, how they hold themselves together, and what might happen if one collided with Earth. The spacecraft will reach that asteroid in July 2031, although it won’t take any more samples. More

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    50 years ago, scientists caught their first glimpse of amino acids from outer space

    Amino acids in a meteorite — Science News, December 5, 1970
    [Researchers] present evidence for the presence of amino acids of possible extraterrestrial origin in a meteorite that fell near Murchison, Victoria, Australia, Sept. 28, 1969.… If over the course of time their finding becomes accepted … it would demonstrate that amino acids, the basic building blocks of proteins, can be and have been formed outside the Earth.
    Update
    Scientists confirmed in 1971 that the Murchison meteorite contained amino acids, primarily glycine, and that those organic compounds likely came from outer space (SN: 3/20/71, p. 195). In the decades since, amino acids and other chemical precursors to life have been uncovered in other fallen space rocks. Recent discoveries include compounds called nucleobases and sugars that are key components of DNA and RNA. The amino acid glycine even has been spotted in outer space in the atmosphere of comet 67P/Churyumov-Gerasimenko. Such findings bolster the idea that life could exist elsewhere in the universe. More

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    China is about to collect the first moon rocks since the 1970s

    For the first time in almost half a century, scientists are going to get their hands on new moon rocks.
    The Chinese space agency’s Chang’e-5 spacecraft, which landed on the moon around 10:15 a.m. EST December 1, will scoop up lunar soil from a never-before-visited region and bring it back to Earth a few weeks later. Those samples could provide details about an era of lunar history not touched upon by previous moon missions.
    “We’ve been talking since the Apollo era about going back and collecting more samples from a different region,” says planetary scientist Jessica Barnes of the University of Arizona in Tucson, who works with lunar samples from the American and Soviet Union missions of the 1960s and 1970s. “It’s finally happening.”
    Chang’e-5, the latest in a series of missions named for the Chinese moon goddess (SN: 11/11/18), took off from the China National Space Administration’s launch site in the South China Sea on November 23 and landed in volcanic flatlands on the northwest region of the moon’s nearside.

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    The lander, equipped with a scoop and a drill, will collect about two kilograms of soil and small rocks, possibly from as deep as two meters below the moon’s surface, says planetary scientist Long Xiao of China University of Geosciences in Wuhan.
    The spacecraft has to work fast. With no internal heating mechanism, it has no defenses against the extremely cold lunar night, which can reach –170° Celsius. The entire mission has to fit within one lunar day, about 14 Earth days.
    After the lander collects the sample, a small rocket will bring the lander and the sample back to the orbiter perhaps as early as December 3, although the Chinese space agency has not released the official schedule.
    Once in orbit, the moon material will be packaged into a return capsule and sent back to Earth. The capsule is expected to land in the Inner Mongolia region by December 17.
    The last time new lunar samples were sent back to Earth was 1976, with the end of the Soviet Union’s Luna program. Between those missions and NASA’s Apollo missions, scientists on Earth have about 380 kilograms of moon material to study (SN: 7/15/19). “Perhaps for a long time people thought, been there, done that, when it comes to the moon,” Barnes says.
    Two kilograms of new stuff might not sound like much next to what’s already in hand. But Chang’e-5 is returning samples from an entirely unexplored region. The landing site is in the Mons Rümker region in the northwest region of the nearside of the moon. Like the Apollo and Luna landing sites, Rümker is flat. “The engineering consideration is first, to be safe,” Xiao says.

    All the Apollo and Luna missions visited ancient volcanic plains, where the rocks are between 3 billion and 4 billion years old. Rümker’s volcanic rocks are much younger, around 1.3 billion to 1.4 billion years old. In the ‘60s, scientists didn’t think the moon was still volcanically active that late. More recent studies from lunar orbit and from telescopes have suggested a more complicated volcanic past.
    “With these new samples, we potentially add another pinpoint in our geologic history of the moon,” says Barnes. “We’ll get an idea of, what was the volcanic history like on the moon a billion years ago? That’s something we don’t have access to in the returned samples we already have.”
    The Rümker region is also rich in potassium, rare-Earth elements and phosphorous, often called KREEP elements. Those elements were some of the last to crystalize out of the magma ocean that covered the young moon and can help reveal details of how that process happened. It’s an “exotic flavor” of material, says Barnes. “It’s a really different area, geochemically, to the rest of the moon.”
    One of the biggest challenges for the mission will be drilling that material. The drill can’t change direction once it’s deployed, so it has to attempt to drill through anything directly below it. If the drill hits a large rock, it could fail. So the Chang’e-5 team is hoping for fine, loose soil, Long says.
    Once the sample is back on Earth, it will be stored and cataloged at a curation center in Beijing. Then it will be distributed for scientists to do research.
    “You can’t breathe easy on these types of missions until the samples are back and are safe in the curation place where they’re going to be held,” Barnes says.
    The Chinese space agency plans to share samples with international scientists. A 2011 congressional rule makes it difficult for U.S. scientists to collaborate directly with China, so it’s unclear who will get to work with the rocks. But the discoveries that the new samples will enable go beyond international borders.
    “It doesn’t matter who’s doing it,” says Barnes. “The whole world should be behind this mission and this endeavor. It’s a piece of history.” More

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    Farming on Mars will be a lot harder than ‘The Martian’ made it seem

    In the film The Martian, astronaut Mark Watney (played by Matt Damon) survives being stranded on the Red Planet by farming potatoes in Martian dirt fertilized with feces.
    Future Mars astronauts could grow crops in dirt to avoid solely relying on resupply missions, and to grow a greater amount and variety of food than with hydroponics alone (SN: 11/4/11). But new lab experiments suggest that growing food on the Red Planet will be a lot more complicated than simply planting crops with poop (SN: 9/22/15).
    Researchers planted lettuce and the weed Arabidopsis thaliana in three kinds of fake Mars dirt. Two were made from materials mined in Hawaii or the Mojave Desert that look like dirt on Mars. To mimic the makeup of the Martian surface even more closely, the third was made from scratch using volcanic rock, clays, salts and other chemical ingredients that NASA’s Curiosity rover has seen on the Red Planet (SN: 1/31/19). While both lettuce and A. thaliana survived in the Marslike natural soils, neither could grow in the synthetic dirt, researchers report in the upcoming Jan. 15 Icarus.
    “It’s not surprising at all that as you get [dirt] that’s more and more accurate, closer to Mars, that it gets harder and harder for plants to grow in it,” says planetary scientist Kevin Cannon of the Colorado School of Mines in Golden, Colo., who helped make the synthetic Mars dirt but wasn’t involved in the new study.

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    Soil on Earth is full of microbes and other organic matter that helps plants grow, but Mars dirt is basically crushed rock. The new result “tells you that if you want to grow plants on Mars using soil, you’re going to have to put in a lot of work to transform that material into something that plants can grow in,” Cannon says.
    Biochemist Andrew Palmer and colleagues at the Florida Institute of Technology in Melbourne planted lettuce and A. thaliana seeds in imitation Mars dirt under controlled lighting and temperature indoors, just as astronauts would on Mars. The plants were cultivated at 22° Celsius and about 70 percent humidity.
    Seeds of both species germinated and grew in dirt mined from Hawaii or the Mojave Desert, as long as the plants were fertilized with a cocktail of nitrogen, potassium, calcium and other nutrients. No seeds of either species could germinate in the synthetic dirt, so “we would grow up plants under hydroponic-like conditions, and then we would transfer them” to the artificial dirt, Palmer says. But even when given fertilizer, those seedlings died within a week of transplanting.
    In lab experiments, lettuce was able to grow in Marslike soil from the Mojave Desert (pictured) as long as the soil was fertilized with nitrogen, potassium, calcium and other nutrients.Nathan Hadland
    Palmer’s team suspected that the problem with the synthetic Mars dirt was its high pH, which was about 9.5. The two natural soils had pH levels around 7. When the researchers treated the synthetic dirt with sulfuric acid to lower the pH to 7.2, transplanted seedlings survived an extra week but ultimately died.
    The team also ran up against another problem: The original synthetic dirt recipe did not include calcium perchlorate, a toxic salt that recent observations suggest make up to about 2 percent of the Martian surface. When Palmer’s team added it at concentrations similar to those seen on Mars, neither lettuce nor A. thaliana grew at all in the dirt.
    “The perchlorate is a major problem” for Martian farming, says Edward Guinan, an astrobiologist at Villanova University in Pennsylvania who was not involved in the work. But calcium perchlorate may not have to be a showstopper. “There are bacteria on Earth that enjoy perchlorates as a food,” Guinan says. As the microbes eat the salt, they give off oxygen. If these bacteria were taken from Earth to Mars to munch on perchlorates in Martian dirt, Guinan imagines that the organisms could not only get rid of a toxic component of the dirt, but perhaps also help produce breathable oxygen for astronauts.
    What’s more, the exact treatment required to make Martian dirt farmable may vary, depending on where astronauts make their homestead. “It probably depends where you land, what the geology and chemistry of the soil is going to be,” Guinan says.
    To explore how that variety might affect future agricultural practices, geochemist Laura Fackrell of the University of Georgia in Athens and colleagues mixed up five new types of faux Mars dirt. The recipes for these fake Martian materials, also reported in the Jan. 15 Icarus, are based on observations of Mars’ surface from the Curiosity, Spirit and Opportunity rovers, as well as NASA’s Mars Global Surveyor spacecraft and Mars Reconnaissance Orbiter.
    Each new artificial Mars dirt represents a mix of materials that could be found or made on the Red Planet. One is designed to represent the average composition across Mars, similar to the synthetic material created by Cannon’s team. The other four varieties have slightly different makeups, such as dirt that is particularly rich in carbonates or sulfates. This collection “expands the palette of what we have available” as test-beds for agricultural experiments, Fackrell says.
    She’s now using her stock to run preliminary plant growth experiments. So far, a legume called moth bean, which has similar nutritional content to a soybean but is more drought resistant, has grown the best. “But they’re not necessarily super healthy,” Fackrell says. Future experiments could explore what nutrient cocktails help plants survive in the various fake Martian terrains. But this much is clear, Fackrell says: “It’s not quite as easy as it looks in The Martian.” More

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    Chemical reactions high in Mars’ atmosphere rip apart water molecules

    Mars’ water is being skimmed off the top. NASA’S MAVEN spacecraft found water lofted into Mars’ upper atmosphere, where its hydrogen and oxygen atoms are ripped apart, scientists report in the Nov. 13 Science.
    “This completely changes how we thought hydrogen, in particular, was being lost to space,” says planetary chemist Shane Stone of the University of Arizona in Tucson.
    Mars’ surface was shaped by flowing water, but today the planet is an arid desert (SN: 12/8/14). Previously, scientists thought that Mars’ water was lost in a “slow and steady trickle,” as sunlight split water in the lower atmosphere and hydrogen gradually diffused upward, Stone says.
    But MAVEN, which has been orbiting Mars since 2014, scooped up water molecules in Mars’ ionosphere, at altitudes of about 150 kilometers. That was surprising — previously the highest water had been seen was about 80 kilometers (SN: 1/22/18).
    That high-up water varied in concentration as the seasons changed on Mars, with the peak in the southern summer, when seasonal dust storms are most frequent (SN: 7/14/20). During a global dust storm in 2018, water levels jumped even higher, suggesting dust storms lift water in a “sudden splash,” Stone says.
    The top of Mars’ atmosphere is full of charged molecules that are primed for rapid chemical reactions, especially with water. So water up there is split apart quickly, on average lasting only four hours, leaving hydrogen atoms to float away (SN: 11/27/15). That process is 10 times faster than previously known ways for Mars to lose water, Stone and his colleagues calculated.
    This process could account for Mars losing the equivalent of a 44-centimeter-deep global ocean in the past billion years, plus another 17-centimeter-deep ocean during each global dust storm, the team found. That can’t explain all of Mars’ water loss, but it’s a start. More