The legendary British rock band has been honored by NASA with a rock that the InSight lander rocket-blasted across the Red Planet’s surface last year.
Those of you who frequently read my articles will know that I have a fascination with rolling rocks on celestial bodies. There’s the numerous boulders on the Moon that have been dislodged and rolled down crater sides, leaving their bouncy imprints in the dirt. There’s also the rolling rocks of Ceres. And the theorized rock tracks that are carved into Phobos. Then there’s Mars, the undisputed king of rolling boulders, imaged to beautiful precision by our orbiting armada of spacecraft.
The most famous rolling rock is no boulder, however; it’s barely larger than a golf ball—but it’s now the most famous pebble in the solar system. It’s a little rock that was minding its own business until a car-sized NASA robot rumbled through the Martian skies on Nov. 26, 2018, retro-rockets firing to slow its descent to the ground, that flipped the innocent ruddy bystander three feet (1 meter) from the landing site. It’s sobering to think that that rock probably hasn’t been disturbed for millions of years until that fateful day.
Behold, the “Rolling Stones Rock,” named after rock legends The Rolling Stones and announced tonight by Avengers actor Robert Downey Jr. to tens of thousands of Stones fans at the Rose Bowl Stadium, just before Mick Jagger, Keith Richards, Charlie Watts, Ronnie Wood, and friends rocked Los Angeles to its core. Space exploration doesn’t get much more Hollywood than this:
And a little animated introduction to the rock itself:
“The name Rolling Stones Rock is a perfect fit,” said Lori Glaze, director of NASA’s Planetary Science Division in Washington, in a statement. “Part of NASA’s charter is to share our work with different audiences. When we found out the Stones would be in Pasadena, honoring them seemed like a fun way to reach fans all over the world.”
While, in the grand scheme of things, naming a little rock after The Rolling Stones may not seem like such a big deal (and, besides, it’s an unofficial designation), as my wife and I stood watching the Stones do a blistering performance of “Sympathy For the Devil”, the family next to us were discussing Mars asking what the InSight lander was doing on the Red Planet.
So, mission success, NASA. Mission success.
“Cross-pollinating science and a legendary rock band is always a good thing…”
As the Stones arrive in Los Angeles to continue their No Filter tour, there’s a space-related twist in store at the Rose Bowl Stadium.
It’s been 25 years since the Rolling Stones played at the Rose Bowl Stadium, so SoCal fans of the legendary British rock band are understandably excited. But, for space fans, there’s a little something extra, as actor Robert Downey Jr. teased in a video he posted this morning:
So, what DOES the Rolling Stones, the Rose Bowl, NASA and Robert’s star sign (steady on now) have in common? As he’s an Ares, I’m thinking it’s Mars, a planet that NASA Jet Propulsion Laboratory (which is located near the Rose Bowl) knows more than a thing or two about. And the Stones have a song called “2,000 Light Years From Home”…? OK, I’m reaching a bit on the latter (besides, Mars is much closer to Earth than 2,000 light-years), but there’s definitely something a little Martian going on. Will Curiosity beep a Rolling Stones song from Mount Sharp? Has it got something to do with the upcoming NASA Mars 2020 mission? Will the Mars InSight lander make a cameo? Who knows. But I’m all for melding science with music, so I’m excited.
I, for one, welcome our new Mars desert-dwelling overlords.
It’s a question I’ve been pondering for some time: if we discover microbes eking out an existence on Mars, what might they be called? At first, I presumed it would be a variation on how we designate microbial names on Earth. Something like Staphylococcus aureus but swap out the “aureus” for “ares” (Greek for “Mars”, the god of war) or … something.
As you can see, biology isn’t my strong suit and butchering Latin and Greek is all in a day’s work. So, feeling out of my depth, I decided to leave that thought alone and file the idea under “Interesting, But Needs More Research.” That’s where the topic stayed for a while; I wanted to wait for a related piece of science to appear in a journal that could be a catalyst for my question. And last week, that research surfaced. I saw my opportunity.
Searching for Martians on Earth
The Atacama Desert is an amazing place. Having visited the ESO’s Paranal Observatory and the Atacama Large Millimeter/submillimeter Array in 2016 as a lucky member of the #MeetESO team, I have first-hand experience of that extreme and breathtaking region. While driving between sites, we’d often go for hours without seeing any vegetation or life of any kind. Atacama is the driest place on Earth; its salty, parched soil is bombarded by ultraviolet radiation, and the core of the desert doesn’t receive rain for decades. But just because life isn’t obvious in the arid ‘scapes, that doesn’t mean it’s not there.
The flora and fauna that does call Atacama their home are very specialized in finding ways to thrive. On the smallest life scales, for some microbes that means living underground, which makes them very interesting organisms indeed.
The research was driven, in part, to develop techniques for robotic missions to the Red Planet that will seek out alien bacteria that may be holed up in an underground colony. Remember, Mars has the same land area as Earth, so there’s a lot of real estate to search for microscopic lifeforms. Sure, scientists are smart and can narrow down potentially-habitable regions that they can drop a life-seeking robot on, but once landed on that toxic soil, what kind of methodology should they use to look for these hypothetical bacteria? The Atacama Desert makes for a decent analog of Mars; it’s very dry and its soil is laced with toxic perchlorate salts, so if microbes on Mars bear any resemblance to the nature of microbes in the Atacama, scientists can take a stab at predicting their behavior and guide their Mars rovers to the most likely places where they might be hiding.
Researchers already know that bacterial life occupies even the harshest Atacama regions, but according to team leader Stephen Pointing, a professor at Yale-NUS College in Singapore, the microbes we are familiar with are common species that live on the surface, using sunlight for energy. But Pointing isn’t so interested in what’s on the surface; his rover is fitted with a drill and extraction system that can take samples of soil from underground. During the campaign, Pointing’s team made some compelling discoveries.
“We saw that with increasing depth the bacterial community became dominated by bacteria that can thrive in the extremely salty and alkaline soils,” he told me. “They in turn were replaced at depths down to 80 centimeters by a single specific group of bacteria that survive by metabolizing methane.”
These subsurface microbes are known to science — they have been found in deep mine shafts and other subterranean environments — but they’ve never been found living under the surface of the world’s most arid region. They’ve also fine-tuned their evolution to specifically adapt to this harsh environment. “The communities of bacteria that we discovered were remarkably lacking in complexity, and this likely reflects the extreme stress under which they develop,” said Pointing.
The biggest discovery made during this research was that the subsurface colonies of bacteria were very patchy, said Pointing, a factor that will have ramifications for the search for their Martian cousins. “The patchy nature of the colonization suggest that a rover would be faced with a ‘needle in a haystack’ scenario in the search for Martian bacteria,” he said.
Desert Planet Survivor
This research is a fascinating glimpse into how Earth-based environments are being used to better understand how alien bacteria may evolve in their native environments. But the desert-thriving, methane-munching bacteria of the Atacama may also inspire their name — should they be discovered one day.
Pointing explained: “The way we assign Latin names to bacteria is based on their evolutionary relationship to each other and we measure this using their genetic code. The naming of Martian bacteria would require a completely new set of Latin names at the highest level if Martian bacteria were a completely separate evolutionary lineage — that is they evolved from a different common ancestor to Earth bacteria in a “second genesis” event [and not related to Earth life via panspermia]. If we find truly “native” Martian bacteria I would love to name one, and call it Planeta-desertum superstes, which translates in Latin to ‘survivor on the desert planet.'”
So there we have it, an answer to my question about what our Martian neighbors might be called, if we find them: Planeta-desertum superstes,the desert planet survivor.
Now that Opportunity’s mission is complete, many wistfully lament about “bringing our robot home.” There’s just one problem: it’s already home.
I am fascinated with how we anthropomorphize robots, particularly space robots. We call them “brave,” “pioneers” and even give them genders — usually a “she.” We get emotional when they reach the end of their missions, saying they’ve “died” or, as I like to say, “gone to Silicon Heaven.” But these robots are, for all intents and purposes, tools. Sure, they expand the reach of our senses, allowing us to see strange new worlds and parts of the universe where humans fear to tread, but they’re an assembly of electronics, metal, plastic, sensors, transmitters, wheels and solar panels. They don’t have emotions. They don’t breathe. They don’t philosophize about the incredible feats of exploration they are undertaking. They don’t have genders.
Still, we fall in love. When watching Curiosity land on Mars from NASA’s Jet Propulsion Laboratory, I teared up, full of joy that the six-wheeled hulk of a rover — that I’d met personally in JPL’s clean room a couple of years before — had safely landed on the Red Planet. After watching NASA’s InSight lander touch down on Elysium Planitia, again via JPL’s media room last year, there it was again, I was in love. I’m already anthropomorphizing the heck out of that mission, seeing InSight’s landing as another “heartbeat” on Mars. When the European Rosetta mission found Philae lying on its side like a discarded child’s toy on the surface of comet 67P/Churyumov–Gerasimenko, I jumped up from my desk with joy. When Cassini’s mission at Saturn ended in 2017, I was miserable. When the Chinese rover Yutu rolled off its lander in 2014, I realized I was cheering the robot on. When Spirit got stuck in a sand trap in Gusev Crater, I set up a Google alert for any and all news on the recovery efforts.
These emotions aren’t just for the exciting science and engineering strides humanity makes, there’s a certain inspirational character that each robot brings. Undoubtedly, this character naturally emerges from the wonderful scientists and engineers who design and build these amazing machines, and the social media managers who often “speak” for their robots in first person. But if you strip away the science, the technology and the people who build them, we still personalize our beloved robots, giving them their own character and creating a cartoon personality. I believe that’s a beautiful trait in the human condition (except a few flawed cultural and stereotypical missteps) and can be used to great effect to captivate the general public with the science that these robots do.
So there’s no great surprise about the outpouring of emotion for last week’s announcement that NASA called off the communications efforts with Mars Exploration Rover Opportunity. This kick-ass robot traveled 28 miles and lasted nearly 15 years, until a global dust storm in early 2018 starved it of sunlight. It landed on Mars way back in 2004, with its twin, Spirit, beginning its Martian reign with a hole-in-one, literally — after bouncing and rolling across the regolith after its entry and descent, encased inside a genius airbag system, it plopped inside the tiny Eagle crater. We’ve collectively lived through Opportunity’s adventures and the groundbreaking science it has done. There’s a huge number of terrific robot obituaries out there, so I won’t duplicate those efforts here. There is, however, a recurring sentiment that is somewhat misplaced, though entirely innocent.
Opportunity — like Spirit and all the Mars rovers and landers that have come and gone — died at home.
This may sound like an odd statement, but there seems to be this fascination with “returning” our space robots to Earth. I’ve seen cartoons of the Dr Who traveling through time to “rescue” Opportunity. People have argued for the case of future Mars astronauts returning these artifacts to terrestrial museums. There’s that touching XKCD cartoon of Spirit being “stranded” on Mars after NASA declared it lost in 2010, that is being resurfaced for Opportunity. We want our dusty Mars rover back!
It’s understandable, that rover has been continuously exploring Mars for a decade and a half, many of its fans, including myself, could check in on Opportunity’s adventures daily, browsing the latest batch of raw images that were uploaded to the NASA servers. We love that thing. In the tradition of military service members who die abroad, we go to great efforts to bring their bodies home so they can repatriated; we want to repatriate our science service member back to Earth.
But Opportunity is a robot that was designed for Mars. Every single design consideration took the Martian environment into account. The Red Planet’s gravity is roughly 1/3rd that of Earth, so the weight on its actuators and chassis are 2/3rds less than what they’d experience on our planet. Its motors are too under powered to reliably drive the robot forward on Earth. On Mars, they’re perfect. Granted, the mass of the Mars Exploration Rovers (approximately 185 kg) are a lot less than their supersized cousin, Curiosity (899 kg), but if Opportunity and Spirit had a 90-day mission exploring the dunes of the Californian Mojave Desert, I’m betting they wouldn’t get very far; they would be under-powered and grind to a halt. They’d also likely overheat as they were designed to withstand the incredibly low temperatures on the Martian surface.
The robots we send to Mars are undeniably Martian. If we’re going to anthropomorphize these beautiful machines, let’s think about what they’d want. I’m guessing they’d want to stay on that dusty terrain and not return to the alien place where they were constructed. And, in doing so, they become the first generation of archaeological sites on the Red Planet that, one day, the first biological Martians will visit.
InSight’s recording of Martian winds isn’t what you’d hear if you were on the planet yourself
We live in a world where spacecraft are now routinely landing on other worlds and recording their sounds. Soviet probes aimed at Venus captured the thunder and howling winds on the volcanic world, giving us the first ever audio recording captured beyond Earth. We’ve been able to reconstruct the sound of alien rain on Saturn’s moon Titan. And now, for the first time, we get to hear the low hum of Martian winds sweeping down the planes. Except not exactly. You see, while InSight did in fact record a 10 to 15 mile per hour draft on Martian, the recording’s pitch had to be dialed up and its frequency sped up roughly 100 times for the human ear to make any real sense of it. But why is it so hard to hear them otherwise?
Unlike Venus or Titan, Mars has an extremely thin, barely there atmosphere stripped away by solar winds and with virtually no protection from its weak magnetosphere. It’s so thin and fragile that it might actually make the planet impossible to terraform if we ever wanted to try to make it even a little more like our world. Even hurricane force winds would feel like a gentle breeze because there’s just not enough air to impart any meaningful kinetic energy. So, if you were able to stand on the surface of Mars without a spacesuit, you’d probably hear and feel nothing, hence NASA had to help us out so we could get some appreciation of what they were able to record, which is still exquisitely haunting and beautiful in the end.
What about winds on other planets and moons?
With extremely thick atmospheres, you’d have absolutely no problem hearing and feeling the full force of the wind on worlds like Venus, Jupiter and the other gas giants, and of course, Titan. In the turbulent clouds of gas giants, the winds would never stop and without anything solid to act as a brake, gusts can howl at astonishing speeds. Neptune boasts the fastest winds in the solar system at 1,200 miles per hour, with Saturn not far behind as 1,118 mile per hour gales whip around its equator, making Jupiter seem almost inert by comparison with peak wind speeds of 384 miles per hour around its Great Red Spot.
Exactly how hard that wind would hit you will depend on your altitude in the gas giants’ vast atmospheres but analogies with the impacts of anything between a tornado and a freight train come to mind. At this point, we would consider the kinetic energy of winds on Venus and Titan because they have solid surfaces and very thick atmospheres, but on both worlds, a very odd and interesting thing happens as you descend through the clouds. That atmospheric thickness means that gasses are compressed as you get close and closer to the surface and winds very quickly die down under the mass of the air through which they have to move.
On Titan, winds reach maybe 2 miles per hour at ground level at their strongest. On Venus, they peak at 3 miles per hour. Still, because there’s so much mass in motion, they would feel like a stiff breeze of 20 to 25 miles per hour if we note that the gusts in question are strong enough to scatter small rocks and use the Beaufort scale to translate that into comparable conditions right here on Earth. You would certainly hear it as well, deeper and more ominous than you’d expect, with absolutely no need to increase the pitch or speed up frequency for your ear to know what’s happening.
So, in case you ever look at the night sky and wonder about how different other planets are from the one on which you’re standing, consider that something seemingly as simple as the sound of moving air can be vastly different from world to world, what you’d consider a gentle breeze could be imperceptible on one planet and blow an umbrella out of your hand on another, and that sometimes, to appreciate what our robotic probes are detecting, we need to specially process the data they’ve gathered so you can even start making sense of it.
The NASA mission looks like it’s getting comfortable in Elysium Planitia.
Like any self-respecting social media influencer, Mars’s latest resident is hard at work snapping photos of its new digs. The robot has even thrown in a beautiful selfie for good measure.
NASA’s InSight lander touched down on the Red Planet on Nov. 26 and since then its mission controllers have been hard at work checking out the instrumentation and surroundings. Using its Instrument Deployment Camera, or IDC, InSight has been giving us a tour of its permanent home. Fans on social media have even been nominating names for the rocks that can be seen embedded in the dusty regolith — the only rocks we’ll see close up for the duration of the mission.
Very early on, NASA scientists knew they’d landed in the right place. The beautifully-flat plain of Elysium Planitia has a landscape that is in stark contrast to Curiosity’s Mount Sharp environment; instead of seeing a smorgasbord of geological features — created by ancient water action and ongoing aeolian (wind-blown) processes — Elysium is flat, dusty and appears to only have small-ish rocks strewn over its surface. You see, InSight cares little for what’s on the surface; the science it’s after lies below the stationary lander, all the way to the planet’s core.
“The near-absence of rocks, hills and holes means it’ll be extremely safe for our instruments,” said InSight’s Principal Investigator Bruce Banerdt of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., in a statement. “This might seem like a pretty plain piece of ground if it weren’t on Mars, but we’re glad to see that.”
Now that InSight’s raw image archive is churning out new pictures daily, mission scientists are scoping out its “work space” directly in front of the lander’s robotic arm. Over the coming weeks, optimal positions for InSight’s two main experiments — the Seismic Experiment for Interior Structure (SEIS) andHeat Flow and Physical Properties Package (HP3) —will be decided on and then commands will be sent to the lander to begin the painstaking task of retrieving them from its deck and setting them down on the ground. The main task will be to determine exact locations that are smooth, flat and contain small rocks that are no bigger than half an inch. This will ensure stable contact with the ground so seismic and heat flow measurements can be continuously carried out. InSight is basically going to give Mars an internal examination 24/7, listening to the slightest seismic waves like a doctor would listen to your heartbeat. And it looks like InSight has landed inside a depression, likely created by an ancient crater that has been filled with loose material over time — this is great news for HP3 that has a self-digging probe (called the “mole”) that will now have an easier task of burrowing meters underground.
But what about that selfie? Well, here you go:
This photo is a mosaic composed of 11 different images snapped by the lander’s robotic arm-mounted camera. You can see the lander’s open solar panels and stowed instrumentation on the deck, including SEIS and HP3. And no, the selfie isn’t a fake; by sticking a bunch of individual photos together, they’ve overlapped to edit out any trace of the arm itself. Curiosity does the same thing; so did Opportunity and Spirit. InSight’s older sibling, Phoenix also did it. Selfies are as much the rage on Mars as they are on Earth. Not only do they look cool, they are also useful for mission controllers to monitor the build-up of dust on solar panels, for example.
It’s always fun to browse through the raw image archive for any Mars mission. You see rocks, dust, more rocks and more dust, but then you see something strange, sitting atop the dirt that is like nothing you’ve seen before.
Once, there was a piece of plastic on the ground in front of Curiosity. Plastic! Not alien plastic though, it was likely something that fell off the rover. Mars rover Opportunity even found strange “blueberries” scattered over Meridiani Planum that turned out to be spherical hematite inclusions, basically little balls of mineral that were formed via water action in Mars’ ancient past.
Now there’s a shiny rock just sitting there, in front of Curiosity.
Mars isn’t known for its shiny objects. Everything is a ruddy color (because of the iron-oxide-laced dust that covers everything) and dull. So, when mission controllers saw this small shiny object, it became a focus of interest. They’ve even named it “Little Colonsay.” Don’t get too excited for an explanation that’s too outlandish, but it will be an interesting find if it turns out to be what scientists think it is.
“The planning team thinks it might be a meteorite because it is so shiny,” writes Susanne Schwenzer, Curiosity mission team member.
Meteorites have been discovered on Mars before by the Mars rovers — and Curiosity is no stranger to finding space rocks strewn on the ground — though it would still be a rare find by Curiosity if it does turn out to be a (likely) metallic chunk of space rock. As pointed out by Schwenzer, the team intend to carry out further analysis of the sample, as well as some other interesting rocks, with Curiosity’s ChemCam instrument to decipher what it’s made of.
So as we welcome the InSight mission to the Red Planet to begin its unprecedented study of Mars’ interior, always remember there’s still plenty of gems sitting on the surface waiting to be found.
After following InSight’s journey and dramatic landing on Mars, I’m now emotionally attached to the space robot.
It’s funny how our perception of the robots we send into space changes with the experiences we have with them. Take NASA’s InSight lander, for example.
I was thrilled to be able to see the mission launch on May 5 from my backyard. I was following the launch feed from my office in the early hours of the morning — lift-off was just after 4 a.m., so I was particularly proud that I hadn’t fallen asleep in my home office. Going outside, I looked to the northwest in hopes of glimpsing the light of the Atlas V-401 rocket as it rose into the dark pre-dawn skies. After I’d seen confirmation via the live-stream video of launch from Vandenburg Air Force Base (130 miles to the northwest of my home in Woodland Hills), I stood precariously on a patio chair to get a better view over my roof and… there it was! A bright plume rising and moving very fast toward the south. And then it was gone; the first ever mission to Mars launched from California was on its way into interplanetary space.
Needless to say, I quickly became invested in this space robot, but before I witnessed its launch from afar, it was another anonymous piece of cold space hardware. As soon as I saw its rocket plume, the mission became “real” and InSight was warmly embedded in my emotions.
NASA likes to play up the dangers of sending missions to Mars — and I can’t blame them; more Mars missions have failed than have succeeded. But in recent years, NASA has beaten the odds and landed all of their surface missions and inserted a bunch of satellites into orbit successfully. The last failed NASA mission to Mars was nearly 20 years ago (the Mars Polar Lander in 1999), everything else since — Mars Odyssey, the two Mars Exploration Rovers, Mars Reconnaissance Orbiter, Phoenix lander (InSight’s twin), Curiosity, MAVEN — have all been resounding successes.
Then, on Monday (Nov. 26), after nearly seven months since I saw it fly over my roof, InSight landed on the dusty surface of Mars.
I was fortunate to be at NASA’s Jet Propulsion Laboratory (JPL) on that day, covering the event for Scientific American and HowStuffWorks, and it was a thrill to be in the hub of all the festivities and spend time with my fellow science communicators. JPL always puts together a great event — whether that be the landing of Curiosity over six years ago, or the sad farewell of Cassini last year — and this was no different. The air was thick with anticipation, and all of the mission scientists, managers and engineers were more than willing to share their stories with the dozens of journalists, reporters, social media peeps and TV crews who were in attendance.
Then it was time for landing.
Sending a mission to Mars is risky and, as already pointed out, in the earlier days of humanity throwing stuff at Mars the majority of the missions failed. So, understandably, everyone had a healthy level of nervousness that there was always a chance that InSight might just make another (expensive) crater in the Martian dirt. But that wasn’t to be. And by all accounts, the landing couldn’t have gone better.
The two Mars Cube One (MarCO) spacecraft that were flying with InSight during its time cruising from Earth became the undisputed silicon heroes of the day. Their purpose was to relay telemetry data from InSight as the lander slammed into the Martian atmosphere to commence its hair-raising entry, descent and landing (EDL) on Mars — a.k.a. the Seven Minutes or Six and a Half Minutes Of Terror, depending on who you talk to. As InSight would be landing in a region where there wouldn’t be a satellite overpass for several hours after landing, MarCO became the relay that, in real time (minus the several minute lag-time that it takes for any signal to travel at the speed of light between Mars and Earth) prevented too many chewed fingernails and passed the message to mission control that the lander had landed safely and everything was, well, just perfect.
In the media area, with a live feed streaming from just next door on the JPL campus, any nervousness evaporated when we all cheered with the mission controllers who were celebrating on the screen. Memories of Curiosity’s landing came flooding back. NASA has done it again, we’re on Mars!
And then, despite warnings that it might be some time before we see the first view of Elysium Planitia from InSight’s camera, we became aware that the mood had changed in mission control. Managers were now huddled around a computer terminal. They were receiving the first image only a few minutes after touch down!
Keep in mind that relaying this image would have been impossible without InSight’s MarCO travel buddies. The success of the mission didn’t depend on MarCO, but they sure made the landing event a more lively celebration, rather than a “yes we’re on Mars, but no pictures until tomorrow!” anticlimax. I asked a couple of the MarCO managers what was next for their robotic heroes, and they said that their mission was complete and that they were a proof of concept “that was now proven.” Apparently, managers for other robotic space missions are planning MarCO-like payloads for future missions. Justifiably so.
Monday was a blur, but I remember walking away from JPL feeling emotional and humbled. Humanity is capable of doing incredible, bold things, I thought to myself. Why can’t we be more like this? Discussing the nature of humanity and our contradictory ways can be saved for another day, however.
Now that we’ve lived InSight’s dramatic journey to Mars, the lander has become more than a robot, it’s a bona fide Mars explorer that, like Curiosity and all the landers and rovers that have come before it, is an extension of the human experience. Designed to live in the Martian environment, InSight has arrived home. Hopes are high for some incredible scientific discoveries about Mars’ interior and its evolution, but I’m also hopeful that the mission will inspire people to embrace our natural urge to explore and discover new things about our universe. This time exploration will be done through the eyes of the newest space robot to join its Martian family, but some time in the next couple of decades, it will be human eyes exploring Elysium Planitia.
For more about the science behind InSight, read my articles for Scientific American and HowStuffWorks.com:
Earth has them. So does the Moon. As does Mars. And now we know dwarf planet Ceres has them, too. Could a Martian moon also have them? Well, according to new research, they could explain the mystery behind Phobos’ strange lines that are carved into its dusty surface.
What am I talking about? Boulders. Specifically boulders that have been on the move. Boulders that — in the presence of a gravitational field, no matter how weak — roll and bounce, leaving their grooves on some of our most beloved celestial bodies.
“These grooves are a distinctive feature of Phobos, and how they formed has been debated by planetary scientists for 40 years,” said planetary scientist Ken Ramsley (Brown University) who led the work, in a statement. “We think this study is another step toward zeroing in on an explanation.”
Ever since NASA’s Mariner and Viking missions spied Phobos’ lines in the 1970’s, scientists have debated what could have created them. The ancient natural satellite of Mars is only 27 kilometers wide and possesses long, etched lines that, in some cases, loop around the entirety of the moon’s circumference.
A popular hypothesis for these lines focused on the possibility that Phobos is a dying moon; the tidal forces from Mars ultimately pulling the body apart. In this scenario, the lines are a sign that the moon’s interior is crumbling, creating fault lines in the surface that our space robots have been able to image. Another idea is that the lines were created by crater chains; multiple impacts by smaller rocks that etched out long lines around Phobos’ surface.
However, according Ramsley’s study, which is published in the journal Planetary and Space Science, the real mechanism that created Phobos’ stripes is far more elegant, and more familiar to us Earthlings. What’s more, it was one of the original hypotheses that was posited when the lines were discovered over 40 years ago.
You see, Phobos has a huge, nine-kilometer-wide crater on one side, called Stickney (named after Angeline Stickney who motivated the search for Mars’ natural satellites in the late 19th Century), that was excavated by a massive impact in the moon’s ancient past. Using computer models, the researchers simulated what would happen post-impact and where the excavated material (including some hefty boulders) would have ended up. Although a huge quantity of material would have been lost to space during the Stickney impact, a few large rocks may have been kicked across the moon’s surface — these boulders would have rolled slowly, slow enough to be held in contact with Phobos, but fast enough, in some cases, to make more than one trip around the moon.
But many of these lines intersect one another and don’t appear to be radially blasted from the crater. Also, there are regions on the surface where the lines entirely disappear. Ramsley’s simulation explains these oddities.
The simulations show that because of Phobos’ small size and relatively weak gravity, Stickney stones just keep on rolling, rather than stopping after a kilometer or so like they might on a larger body. In fact, some boulders would have rolled and bounded their way all the way around the tiny moon. That circumnavigation could explain why some grooves aren’t radially aligned to the crater. Boulders that start out rolling across the eastern hemisphere of Phobos produce grooves that appear to be misaligned from the crater when they reach the western hemisphere.
This also helps to explain why many of these lines cross and superimpose themselves on one another: Grooves that were laid down by boulders rolling immediately after the impact were crossed by boulders that completed a complete traverse of the globe of the moon, some ending up where they started, minutes or hours later. This also explains why Stickney itself has grooves inside its crater basin.
But there’s a blank area on Phobos that appears to contain no grooves, a phenomenon that the simulation also addresses. This region is located at a comparatively low elevation part of Phobos, surrounded by a higher-elevation lip. “It’s like a ski jump,” said Ramsley. “The boulders keep going but suddenly there’s no ground under them. They end up doing this suborbital flight over this zone.
“We think this makes a pretty strong case that it was this rolling boulder model accounts for most if not all the grooves on Phobos.”
As a fan of rolling boulders on other worlds, I particularly enjoy imagining the lumbering slow roll of these massive rocks that circumnavigated Phobos. They had to keep their roll slow so not to achieve escape velocity, but fast enough to leave their indelible marks for humans to ponder their origins.
When rains came to one of the driest places on Earth, an unprecedented mass extinction ensued.
The assumption was that this rainfall would turn this remote region of the Atacama Desert in Chile into a wondrous, floral haven — dormant seeds hidden in the parched landscape would suddenly awake, triggered by the “life-giving” substance they hadn’t seen for centuries — but it instead decimated over three quarters of the native bacterial life, microbes that shun water in favor of the nitrogen-rich compounds the region has locked in its dry soil.
In other words, death fell from the skies.
“We were hoping for majestic blooms and deserts springing to life. Instead, we learned the contrary, as we found that rain in the hyperarid core of the Atacama Desert caused a massive extinction of most of the indigenous microbial species there,” said astrobiologist Alberto Fairen, who works at Cornell Cornell University and the Centro de Astrobiología, Madrid. Fairien is co-author of a new study published in Nature’s Scientific Reports.
“The hyperdry soils before the rains were inhabited by up to 16 different, ancient microbe species. After it rained, there were only two to four microbe species found in the lagoons,” he added in a statement. “The extinction event was massive.”
Climate models suggest that these rains shouldn’t hit the core regions of Atacama more than once every century, though there is little evidence of rainfall for at least 500 years. Because of the changing climate over the Pacific Ocean, however, modern weather patterns have shifted, causing the weird rain events of March 25 and Aug. 9, 2015. It also rained more recently, on June 7, 2017. Besides being yet another reminder about how climate change impacts some of the most delicate ecosystems on our planet, this new research could have some surprise implications for our search for life on Mars.
Over forty years ago, NASA carried out a profound experiment on the Martian surface: the Viking 1 and 2 landers had instruments on board that would explicitly search for life. After scooping Mars regolith samples into their chemical labs and adding a nutrient-rich water mix, one test detected a sudden release of carbon dioxide laced with carbon-14, a radioisotope that was added to the mix. This result alone pointed to signs that Martian microbes in the regolith could be metabolizing the mixture, belching out the CO2.
Alas, the result couldn’t be replicated and other tests threw negative results for biological activity. Scientists have suggested that this false positive was caused by inorganic reactions, especially as, in 2008, NASA’s Phoenix Mars lander discovered toxic and highly reactive perchlorates is likely common all over Mars. Since Viking, no other mission has attempted a direct search for life on Mars and the missions since have focused on seeking out water and past habitable environments rather than directly testing for Mars germs living on modern Mars.
With this in mind, the new Atacama microbe study could shed some light on the Viking tests. Though the out-gassing result was likely a false positive, even if all the samples collected by the two landers contained microscopic Martians, the addition of the liquid mix may well have sterilized the samples — the sudden addition of a large quantity of water is no friend to microbial life that has adapted to such an arid environment.
“Our results show for the first time that providing suddenly large amounts of water to microorganisms — exquisitely adapted to extract meager and elusive moisture from the most hyperdry environments — will kill them from osmotic shock,” said Fairen.
Another interesting twist to this research is that NASA’s Mars rover Curiosity discovered nitrate-rich deposits in the ancient lakebed in Gale Crater. These deposits might provide sustenance to Mars bacteria (and may be a byproduct of their metabolic activity), like their interplanetary alien cousins in Atacama.
As water-loving organisms, humans have traditionally assumed life elsewhere will bare similar traits to life as we know it. But as this study shows, some life on Earth can appear quite alien; the mass extinction event in the high deserts of Chile could teach us about how to (and how not to) seek out microbes on other planets.