Recent images from ESA’s Mars Express spacecraft reveal long rows of crater-like depressions lining the flanks of ancient Martian volcanoes located in the planet’s vast Tharsis region. Rather than being the result of impact events, these “pit chains” were likely caused by underground lava flows — and could be a prime location for look for life.
Like similar features found on Earth, lava tubes on Mars are the result of rivers of magma that carved channels beneath the surface. When these channels empty out, a hollow tube is left. If the roof of a particularly large tube is near the surface the roof can eventually collapse, creating a surface depression… or, in some cases, opening up to the surface entirely.
Even though volcanism on Mars isn’t currently active — the last eruptions probably took place at least over a million years ago — the features left by volcanic activity are still very much present today and likely well-preserved beneath the Martian surface.
Shielded from harsh solar and cosmic radiation, the interior of such lava tubes could provide a safe haven for microbial life — especially if groundwater had found its way inside at some point.
Even though the surface of Mars can receive 250 times the radiation levels found on Earth, the layers of soil and rock surrounding the tubes can provide adequate protection for life, whether it be ancient Martian microbes or future explorers from Earth.
Of course, water and protection from radiation aren’t the only factors necessary for life. There also needs to be some source of heat. Fortunately, the pit chains imaged by Mars Express happen to be within one of the most volcano-laden areas of the Red Planet, a region called the Arcadia quadrangle. Within this area exist some of the largest volcanoes on Mars — and the Tractus Catena pits are located right in the middle of them.
If a heat source were ever to have been beneath the surface of Mars, there would be a good chance it would have been here.
And if our own planet is any measure of such things, where there’s heat and water there is often some form of life — however extreme the conditions may be.
“I’d like to see us land ON a volcano,” Dr. Tracy Gregg, a volcanologist with the University of Buffalo, had once told Universe Today back in 2004. “Right on the flanks. Often the best place to look for evidence of life on any planet is near volcanoes.”
“That may sound counterintuitive, but think about Yellowstone National Park , which really is nothing but a huge volcano,” Gregg elaborated. “Even when the weather in Wyoming is 20 below zero, all the geysers, which are fed by volcanic heat, are swarming with bacteria and all kinds of happy little things cruising around in the water. So, since we think that the necessary ingredients for life on Earth were water and heat, we are looking for the same things on Mars.”
As far as any remaining geothermal activity still happening beneath the Martian surface?
“I strongly suspect there are still molten (or at least mushy) magma bodies beneath the huge Tharsis volcanoes,” Gregg had said. (Read the full article here.)
On Earth, lava tubes, caves and underground spaces of all kinds harbor life, often specialized forms that are found no place else. Could this be (or have once been) the case on Mars as well? Only future exploration will tell. Until then, places like Tractus Catena will remain on scientists’ short list of places to look.
Researchers from the Center of Astrobiology (CAB) in Spain and the Catholic University of the North in Chile have found an “oasis” of microorganisms living two meters beneath the arid soil of the Atacama, proving that even on the driest place on Earth, life finds a way.
Chile’s Atacama Desert receives on average less than .01 cm (.004 inches) of rain per year. In some locations rain has not fallen for over 400 years. But even in this harsh environment there is moisture… just enough, at least, for rock salts and other compounds that can absorb any traces of water to support microbial life beneath the surface.
Using a device called SOLID (Signs Of LIfe Detection) developed by CAB, the researchers were able to identify the presence of microorganisms living on thin films of water within the salty subsurface soil.
Even the substrate itself is able to absorb moisture from the air, concentrating it into films only a few microns thick around the salt crystals. This gives the microorganisms everything they need to survive and flourish — two to three meters underground.
At that depth, there is no sunlight and no oxygen, but there is life.
And even when researchers dug to a depth of five meters (a little over 16 feet) and took samples back to a lab, they were able to not only locate microorganisms but also revive them with the addition of a little water.
Of course, the implications for finding life — or at least the remains of its past existence — on Mars is evident. Mars has been shown to have saline deposits in many regions, and the salt is what helps water remain liquid, longer.
“The high concentration of salt has a double effect: it absorbs water between the crystals and lowers the freezing point, so that they can have thin films of water (in brine) at temperatures several degrees below zero, up to minus 20 C,” said Victor Parro, researcher from the Center of Astrobiology (INTA-CSIC, Spain) and coordinator of the study. This is within the temperature range of many regions of Mars, and also anything located several meters below the surface would be well protected from UV radiation from the Sun.
“If there are similar microbes on Mars or remains in similar conditions to the ones we have found in Atacama, we could detect them with instruments like SOLID,” Parro said.
The development of a new version of the SOLID instrument is currently underway for ESA’s ExoMars program.
NASA’s long lived Opportunity rover has discovered the most scientifically compelling evidence yet for the flow of liquid water on ancient Mars. The startling revelation comes in the form of a bright vein of the mineral gypsum located at the foothills of an enormous crater named Endeavour, where the intrepid robot is currently traversing. See our mosaic above, illustrating the exact spot.
Update: ‘Homestake’ Opportunity Mosaic above has just been published on Astronomy Picture of the Day (APOD) – 12 Dec 2011 (by Ken Kremer and Marco Di Lorenzo)
Researchers trumpeted the significant water finding this week (Dec. 7) at the annual winter meeting of the American Geophysical Union (AGU) in San Francisco.
“This gypsum vein is the single most powerful piece of evidence for liquid water at Mars that has been discovered by the Opportunity rover,” announced Steve Squyres of Cornell University, Ithaca, N.Y., Principal Investigator for Opportunity, at an AGU press conference.
The light-toned vein is apparently composed of the mineral gypsum and was deposited as a result of precipitation from percolating pools of liquid water which flowed on the surface and subsurface of ancient Mars, billions of years ago. Liquid water is an essential prerequisite for life as we know it.
“This tells a slam-dunk story that water flowed through underground fractures in the rock,” said Squyres. “This stuff is a fairly pure chemical deposit that formed in place right where we see it. That can’t be said for other gypsum seen on Mars or for other water-related minerals Opportunity has found. It’s not uncommon on Earth, but on Mars, it’s the kind of thing that makes geologists jump out of their chairs.”
The light-toned vein is informally named “Homestake”, and was examined up close by Opportunity’s cameras and science instruments for several weeks this past month in November 2011, as the rover was driving northwards along the western edge of a ridge dubbed ‘Cape York’ – which is a low lying segment of the eroded rim of Endeavour Crater.
Veins are a geologic indication of the past flow of liquid water
Opportunity just arrived at the rim of the 14 mile (22 kilometere) wide Endeavour Crater in mid-August 2011 following an epic three year trek across treacherous dune fields from her prior investigative target at the ½ mile wide Victoria Crater.
“It’s like a whole new mission since we arrived at Cape York,” said Squyres.
‘Homestake’ is a very bright linear feature.
“The ‘Homestake’ vein is about 1 centimeter wide and 40 to 50 centimeters long,” Squyres elaborated. “It’s about the width of a human thumb.”
Homestake protrudes slightly above the surrounding ground and bedrock and appears to be part of a system of mineral veins running inside an apron (or Bench) that in turn encircles the entire ridge dubbed Cape York.
In another first, no other veins like these have been seen by Opportunity throughout her entire 20 miles (33 kilometers) and nearly eight year long Martian journey across the cratered, pockmarked plains of Meridiani Planum, said Squyres.
The veins have also not been seen in the higher ground around the rim at Endeavour crater.
“We want to understand why these veins are in the apron but not out on the plains,” said the mission’s deputy principal investigator, Ray Arvidson, of Washington University in St. Louis. “The answer may be that rising groundwater coming from the ancient crust moved through material adjacent to Cape York and deposited gypsum, because this material would be relatively insoluble compared with either magnesium or iron sulfates.”
Opportunity was tasked to engage her Microscopic Imager and Alpha Particle X-ray Spectrometer (APXS) mounted on the terminus of the rover’s arm as well as multiple filters of the mast mounted Panoramic Camera to examine ‘Homestake’.
“The APXS spectrometer shows ’Homestake’ is chock full of Calcium and Sulfur,” Squyres gushed.
The measurements of composition with the APXS show that the ratio points to it being relatively pure calcium sulfate, Squyres explained. “One type of calcium sulfate is gypsum.”
Calcium sulfate can have varying amounts of water bound into the minerals crystal structure.
The rover science team believes that this form of gypsum discovered by Opportunity is the dihydrate; CaSO4•2H2O. On Earth, gypsum is used for making drywall and plaster of Paris.
The gypsum was formed in the exact spot where Opportunity found it – unlike the sulfate minerals previously discovered which were moved around by the wind and other environmental and geologic forces.
“There was a fracture in the rock, water flowed through it, gypsum was precipitated from the water. End of story,” Squyres noted. “There’s no ambiguity about this, and this is what makes it so cool.”
At Homestake we are seeing the evidence of the ground waters that flowed through the ancient Noachian rocks and the precipitation of the gypsum, which is the least soluble of the sulfates, and the other magnesium and iron sulfates which Opportunity has been driving on for the last 8 years.
“Here, both the chemistry, mineralogy, and the morphology just scream water,” Squyres exclaimed. “This is more solid than anything else that we’ve seen in the whole mission.”
It’s inconceivable that the vein is something else beside gypsum, said Squyres.
As Opportunity drove from the plains of Meridiani onto the rim of Endeavour Crater and Cape York, it crossed a geologic boundary and arrived at a much different and older region of ancient Mars.
The evidence for flowing liquid water at Endeavour crater is even more powerful than the silica deposits found by Spirit around the Home Plate volcanic feature at Gusev Crater a few years ago.
“We will look for more of these veins in the [Martian] springtime,” said Squyres.
If a bigger, fatter vein can be found, then Opportunity will be directed to grind into it with her still well functioning Rock Abrasion Tool, or RAT.
Homestake was crunched with the wheels – driving back and forth over the vein – to break it up and expose the interior. Opportunity did a triple crunch over Homestake, said Arvidson.
Homestake was found near the northern tip of Cape York, while Opportunity was scouting out a “Winter Haven” location to spend the approaching Martian winter.
Arvidson emphasized that the team wants Opportunity to be positioned on a northerly tilted slope to catch the maximum amount of the sun’s rays to keep the rover powered up for continuing science activities throughout the fast approaching Martian winter.
“Martian winter in the southern hemisphere starts on March 29, 2012. But, Solar power levels already begin dropping dramatically months before Martian winter starts,” said Alfonso Herrera to Universe Today, Herrera is a Mars rover mission manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
“Opportunity is in excellent health,” said Bruce Banerdt, the Project Scientist for the Mars rover mission at JPL.
“This has been a very exciting time. We’ll head back south in the springtime and have a whole bunch of things to do with a very capable robot,” Squyres concluded.
Meanwhile, NASA’s next leap in exploring potential Martian habitats for life – the car sized Curiosity Mars Science Lab rover – is speeding towards the Red Planet.
Read Ken’s continuing features about Opportunity starting here:
What does a more than three billion year old sandstone formation in Western Australia have in common with Mars? The Aussie stones contain the oldest living microbial record of life on Earth – and it might be the basis of fossil discovery on Mars. The early Archaean rocks are providing geologists with microfossil evidence that early life might have been utilizing sulpher – instead of oxygen – for their ecosystems.
“At last we have good solid evidence for life over 3.4 billion years ago. It confirms there were bacteria at this time, living without oxygen,” said co-researcher Professor Martin Brasier at Oxford University, UK. “Such bacteria are still common today. Sulphur bacteria are found in smelly ditches, soil, hot springs, hydrothermal vents – anywhere where there’s little free oxygen and they can live off organic matter,” he explained.
But providing morphological evidence for these sulphur-metabolizing bacteria hasn’t been as easy as just digging up some stones. The first detection came in 2007 at Strelley Pool, a now arid area which may have once been an estuary or shallow water region. Associated with micrometre-sized pyrite crystals, these microstructures show all the right ingredients for early life properties, such as hollow cell lumens and carbonaceous cell walls enriched in nitrogen. Spheroidal and ellipsoidal forms are good indicators of bacterial formations and tubular sheaths point to multiple cell growth. They also display pyrite content, but there’s no “fool’s gold” here in these light isotopes… it’s a metabolic by-products of the cells.
“Life likes lighter isotopes, so if you have a light signature in these minerals then it looks biological,” said lead author Dr David Wacey from the University of Western Australia. “There are ways to get the same signature without biology, but that generally requires very high temperatures. So when you put together the light isotope signature with the fact the pyrite is right next to the microfossils – just a couple of microns away – then it really does look like there was a whole sulphur ecosystem there,” he reported to BBC News.
So what does this discovery have to do with Mars? In its northern hemisphere is a region called Nili Fossae which photographically bears a strong resemblance to Australia’s Pilbara region – home to Strelley Pool. With a huge amount of clay minerals documented, Nili Fossae just might be the ideal place for US space agency’s Curiosity-Mars Science Laboratory rover mission to begin a search for early Martian life forms. But don’t get too excited just yet… The study on a remote planet is going to prove even more difficult than here on Earth.
“Some of the instruments we used can fill a whole room, but some of them can be miniaturised,” said Dr Wacey. “A rover could narrow down the targets but then you’d really have to bring samples back to Earth to study them in detail.”
Scientists leading NASA’s Mars rover team have selected “Spirit Point” as the name for the spot where the “Opportunity” Mars rover will arrive at her next destination – Endeavour Crater. The site was named in honor of the death of the “Spirit” Mars Exploration Rover, which NASA recently declared has ceased all communications with Earth.
Spirit’s passing comes after more than six highly productive years roving the surface of the red planet as humankind’s surrogate. NASA concluded the last attempt to communicate with Spirit in a transmission on May 25, 2011.
“First landfall at Endeavour will be at the southern end of Cape York [at Spirit Point],” Steve Squyres told me. Squyres of Cornell University, Ithaca, N.Y., is principal investigator for the rovers. Read tributes from the Spirit rover science team below.
In memory of Spirit, the last panorama she snapped on Sol 2175 in February 2010 was featured on Astronomy Picture of the Day (APOD) on May 30, 2011 and is the lead image here. The photo mosaic was created by Marco Di Lorenzo and Ken Kremer and shows some of the last scenes that Spirit ever photographed.
Endeavour’s massive rim consists of a series of ridges. Cape York is a 400 foot wide (120 meters) rim fragment at the western edge of Endeavour. Opportunity should reach “Spirit Point” before the end of this year, 2011.
“Spirit Point” was chosen as the site at Endeavour to commemorate the scientific achievements of Opportunity’s twin sister “Spirit”. Endeavour Crater was determined to be Opportunity’s long term destination nearly three ago after she departed the environs of Victoria crater.
“The Initial exploration plan will be decided when we get closer. The [science] priorities will depend on what we find,” Squyres added.
Since August 2008, the blistering pace of Opportunity’s long overland trek of about 11 miles (18 kilometers) has brought the golf cart sized robot to within about 2 miles (3 kilometers) of the rim of the humongous Endeavour crater – some 14 miles (22 kilometers) in diameter. Endeavour is more than 20 times wider than Victoria crater and by far the largest feature the Opportunity will ever explore – see route maps below.
“Spirit achieved far more than we ever could have hoped when we designed her,” according to Squyres in a NASA statement. “This name will be a reminder that we need to keep pushing as hard as we can to make new discoveries with Opportunity. The exploration of Spirit Point is the next major goal for us to strive for.”
The imaging team of Marco Di Lorenzo and Ken Kremer created a series of Spirit photomosaics from publically available images to illustrate the location and hazardous nature of Spirits final resting place – which fortuitously turned out to be a scientific goldmine revealing new insights into the flow of liquid water on Mars billions of years ago.
The western rim of Endeavour possesses geological deposits far older than any Opportunity has investigated before and which may feature environmental conditions that were more conducive to the potential formation of ancient Martian life forms.
Spirits last transmissions to Earth took place in March 2010, before she entered hibernation mode due to ebbing solar power and succumbed to the likely damaging effects of her 4th Martian winter.
Spirit was closing in on her next science target, a mysterious volcanic feature named Von Braun, when she became mired in a sand trap named “Troy” on the outskirts of the eroded volcano named “Home Plate, just about 500 feet away. See our mosaics.
Unable to escape and absent of sufficient power to run critical survival heaters, Spirit experienced temperatures colder than ever before that probably crippled fragile electronics components and connections and prevented further communications – although no one knows for sure.
NASA’s twin rovers Spirit and Opportunity have been exploring the Martian terrain on opposite sides of the red planet since the dynamic duo successfully landed over 7 years ago in January 2004.
Both robots were expected to last just three months but have accumulated a vast bonus time of exploration and discovery in numerous extended mission phases.
*** Several top members of the rover science team kindly provided me some comments (below) to sum up Spirits achievements and legacy and what’s ahead for Opportunity at Endeavour.
Ray Arvidson of Washington University, St Louis, Deputy Principal Investigator for the rovers:
“Spirit’s last communication with Earth was in March 2010 as the southern hemisphere winter season began to set in, the sun was low on the horizon, and the rover presumably stopped communicating to use all available solar power to charge the batteries.
Von Braun was one of the two destinations Spirit was traveling to when the rover became embedded in soft sands in the valley to the west of Home Plate.
Von Braun is a conically-shaped hill to the south of Home Plate, Inner Basin, Columbia Hills. Goddard is an oval-shaped shallow depression to the west of von Braun and was the second area to be visited by Spirit. Both von Braun and Goddard are suspected to be volcanic features.
During Spirit’s six year and two month mission the vehicle acquired remote sensing and in-situ observations that conclusively demonstrated that the ancient Columbia Hills in Gusev Crater expose materials that have been altered in water-related environments, including ground water corrosion and generation of sulfate and opaline minerals in volcanic steam vents and perhaps hydrothermal pools.
Together with its sister rover, Opportunity, the Mars Exploration Rover Mission, was designed to “follow the water” and return data that would allow us to test the hypothesis that water was at and near the surface during previous epochs.
Opportunity is still exploring the evidence in Meridiani for ancient shallow lakes and is on the way to outcrops on the rim of Endeavour crater, a ~20 km wide crater that exposes the old Noachian crust that shows evidence from orbital data for hydrated clay minerals.
These two rovers have performed far beyond expectations, unveiled the early, wet history of Mars, and have made an enormous scientific return on investment.”
Steve Squyres of Cornell University, Ithaca, N.Y., Principal Investigator for the rovers:
“Our best hope for hearing from Spirit was last fall. When that didn’t happen, we began a long, careful process of trying every possible approach to re-establishing contact. But it slowly became clear that it was unlikely, and I personally got used to the idea that Spirit’s mission was probably over several months ago.
Once that right front wheel failed, Spirit’s days were numbered in that kind of terrain. It wouldn’t have made any difference if we had tried to move Spirit sooner. We were very lucky to have survived as long as we did.
One of the lessons learned is to try to keep the wheels from failing.
It’s very sad to lose Spirit. But two things have softened the blow. First we’ve had a long time to get used to the idea. Second, even though Spirit is dead, she died an honorable death. If we’d lost her early in the mission, before she accomplished so much, it would have been much harder. But she accomplished so much more than any of us expected, the sadness is very much tempered with satisfaction and pride.
The big scientific accomplishments are the silica deposits at Home Plate, the carbonates at Comanche, and all the evidence for hydrothermal systems and explosive volcanism. What we’ve learned is that early Mars at Spirit’s site was a hot, violent place, with hot springs, steam vents, and volcanic explosions. It was extraordinarily different from the Mars of today.
Opportunity is heading at high speed for the rim of Endeavour Crater. First landfall will be at the southern end of Cape York. She should be there in not too many more months.
It hasn’t yet been decided where Opportunity will attempt to climb up Endeavour… we’ll see when we get there.
The phyllosilicates are a high priority, but the top priority depends on what we find.
I hope Spirits legacy will be the inspiration that people, especially kids, will take away from Spirit’s mission. I have had long, thoughtful conversations about Spirit with kids who have had a rover on Mars as long as they can remember. And my fondest hope for Spirit is that somewhere there are kids who will look at what we did with her, and say to themselves “well, that’s pretty cool… but I bet when I grow up I can do better. That’s what we need for the future of space exploration.
Spirit existed, and did what she did, because of the extraordinary team of engineers and scientists who worked so hard to make it possible. It’s a team that I’m incredibly proud to have been a small part of. Working with them has been quite literally the adventure of a lifetime.”
Jim Bell of Arizona State University, lead scientist for the rovers Pancam stereo panoramic camera:
“It is with a bittersweet sense of both sadness and pride that NASA announced the official end of the mission for the Mars Exploration Rover Spirit.
The Spirit team has seen the end coming since communications were lost with the rover in March 2010. Mission engineers made heroic efforts to reestablish contact. In the end Spirit was conquered by the extremely cold Martian winter and its two broken wheels, which prevented its dusty solar panels from pointing toward the Sun.
But what a mission! Designed to last 90 days, Spirit kept going for more than six years, with the team driving the rover almost 5 miles (8 km) across rocky volcanic plains, climbing rugged ancient hills, and scurrying past giant sand-dune fields. It eventually spent most of the mission near the region known as Home Plate, which is full of layered, hydrated minerals.
Data from the rover enabled dozens of scientific discoveries, but three stand out to me as most important:
Hydrated sulfate and high-silica soils in the Columbia Hills and around Home Plate.
These minerals, and the environment in which they occur (Home Plate is a circular-shaped, finely layered plateau that may be the eroded remains of a volcanic cone or other hydrothermal deposit), tell us that at some point in the past history of Gusev there was liquid water and there were heat sources — two key ingredients needed to consider the area habitable for life as we know it.
Carbonate minerals in some of the rocks within the Columbia Hills.
Carbonates were expected on Mars, if indeed the climate was warmer and wetter in the past. However, their detection has been elusive so far. Indeed, the Spirit team had to work hard to uncover the signature of carbonates years after the rover made the measurements. As the analysis continues the results for Mars in general could be profound.
An incredible diversity of rock types, from all over Mars, that Spirit was able to sample in Gusev crater.
Some of the rocks appear to be from local volcanic lava flows or ash deposits. But others have likely been flung in to the area over time by distant impacts or volcanoes, and a few even appear to be meteorites, flung in from outer space. Spirit’s instruments provided the team with the ability to recognize this amazing diversity, and thus to learn much more about Mars in general, not just Gusev in particular.
Spirit also helped us test an experiment: If we put all the rover’s images out on the Web for everyone in the world to see, in near real-time, would people follow along? They did!
I wonder if, maybe 10 or 15 years from now, I’ll meet some young colleagues who were turned on to space exploration by being able to check out the latest Spirit images from Mars from their classroom, or living room, every day when they were a kid. That would be extremely satisfying — and a great testament to the power of openly sharing data from space exploration missions like Spirit’s.
Meanwhile, Opportunity continues to rove on to city-size Endeavour crater, where orbital measurements have identified, for the first time in either rover’s mission, the signatures of clay minerals in the crater’s rim. Clays are also formed in water, but in less acidic, perhaps more life-friendly water than the sulfates that Opportunity has been mapping thus far.”
Rob Manning, Jet Propulsion laboratory, Pasadena, CA., Mars Rover Spacecraft System Engineering team lead
“Although Opportunity has proven her endurance, Spirit was the one we struggled with the hardest to get what she earned. Suffering from late repair and modification, a blown fuse in her power system and with possibly damaged circuits, she was very late getting out the door and onto the pad in Florida.
Unlike Opportunity, whose Hematite-laden Meridiani destination had been established long before launch, Spirit was launched with a great deal of uncertainty on where she would find herself on Mars. Would it be the flat and safe plains of Elysium? Would the intriguing but rough ancient Gusev crater with what appears to have been an ancient river flowing into a giant but now dry lake?
If Opportunity failed to get on her way to Mars, would her destination become Meridiani? Would Spirit have also been as lucky to find herself bouncing into a tiny rock-outcropped crater as Opportunity had?
Only after the successful launch of Opportunity followed by further successful rocket and airbag tests to confirm that the landing system design would work in the rougher terrain inside Gusev crater allowed us to seal her fate and her permanent home.
She would go Gusev and test the Gusev lake hypothesis. Sadly the surface of Gusev where she came to rest revealed a meteor impact-tilled lake of ancient lava. Any signs of ancient water lake beds and other fantastic discoveries would have to wait until she surmounted many more obstacles including summiting a formidable hill her designers never intended her to attempt.
Spirit, her designers, her builders, her testers, her handlers and I have a lot to be thankful for.
That NASA, the congress and the public were willing to trust us with this daunting feat is perhaps a statement about the persistent spirit of discovery that remains in all of us.
Data from the Mars Reconnaissance Orbiter suggests that there could be habitable environments underground on Mars – in the past, and perhaps even today. Scientists discovered evidence of long-sought-after hydrothermally altered carbonate-bearing rocks which were once deep within the Red Planet, exposed within an impact crater. “Carbonate rocks have long been a Holy Grail of Mars exploration for several reasons,” said Joseph Michalski from the Planetary Science Institute. He explained that on Earth, carbonates form with the ocean and within lakes, so the same could be true for ancient Mars. “Such deposits could indicate past seas that were once present on Mars. Another reason is because we suspect that the ancient Martian atmosphere was probably denser and CO2-rich, but today the atmosphere is quite thin so we infer that the CO2 must have gone into carbonate rocks somewhere on Mars.”
This unique mineralogy was spotted within the central peak of a crater to the southwest of a giant Martian volcanic province named Syrtis Major. With infrared spectra from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), planetary geologists detected the hydrothermal minerals from their spectroscopic fingerprints. Visible images from the HiRISE camera (High Resolution Imaging Science Experiment) on board MRO show that the carbonates and hydrated silicate minerals occur within deformed bedrock that was exhumed by an ancient meteor impact that poked through the volcanic upper crust of Mars.
The carbonate-bearing rocks were once likely about 6 km (about 4 miles) underground. The carbonate minerals exist along with hydrated silicate minerals of a likely hydrothermal origin.
While this is not the first detection of carbonates on Mars, Michalski said, “This detection is significant because it shows other carbonates detected by previous workers, which were found in a fairly limited spatial extent, were not a localized phenomenon. Carbonates may have formed over a very large region of ancient Mars, but been covered up by volcanic flows later in the history of the planet. A very exciting history of water on Mars may be simply covered up by younger lava!”
The discovery also has implications for the habitability of the Martian crust. “The presence of carbonates along with hydrothermal silicate minerals indicates that a hydrothermal system existed in the presence of CO2 deep in the Martian crust,” Michalski says. “Such an environment is chemically similar to the type of hydrothermal systems that exist within the ocean floor of Earth, which are capable of sustaining vast communities of organisms that have never seen the light of day.
“The cold, dry surface of Mars is a tough place to survive, even for microbes. If we can identify places where habitable environments once existed at depth, protected from the harsh surface environment, it is a big step forward for astrobiological exploration of the red planet.”
Michalski and co-author Paul B. Niles of NASA Johnson Space Center recently published the results in a paper titled “Deep crustal carbonate rocks exposed by meteor impact on Mars” in Nature Geoscience.
Is there life on other planets? That has been a question raised from the early beginnings of science fiction. The notion was scoffed at as pure mind play for dreamers and the occasional grifter selling rides to the Moon. At least it was until we were able to reach into space and discover new facts and gather new intel.
The possibility of life on Mars(outside sci-fi books) had been proposed as early as the 1950’s, but there was no real way to prove or disprove the theory until the launch of Mariner 4 in 1965. The spacecraft was able to return the first photographs of the planet’s surface. The news was all bad for those who had hoped for signs of life on the planet. The surface was too extreme and desolate for any type of known life form. The Voyager probes found radiolabeled carbon dioxide, but no organic molecules. Those results give mixed signals and are inconclusive at best. The results have been used to support the possibility of a microorganism named Gillevinia straata.
The Phoenix lander touched down on the Martian surface in May of 2008. The lander dug a trench on the area of the northern pole. No bacteria was found but the samples did contain bound water and carbon dioxide. The most positive evidence of life in the Martian past are meteorites from the planet. 34 exist and 3 show signs of microscopic fossilized bacteria.
Another viable possibility for life on other planets would be those similar to Gliese 581c. These planets are within the habitable zone(for human life) of their main sequence star. These planets appear to have a temperature that would allow liquid water and atmosphere’s that seem spectroscopically close to Earth’s. The information that is needed would detail the greenhouse effect on these planets. If that was available, we would be able to determine suitability for human life.
All of our efforts to answer the question ‘Is there life on other planets?’ are based on finding life that is similar to that on Earth. That is a typically arrogant line of research. Where is it written that the Earth type of life form is pervasive?
We have written many articles about the possibility of life on other planets for Universe Today. Here’s an article about the life on other planets, and here’s an article about life on Mars.
If you’d like more info on the search for life on other planets, check out the NASA Astrobiology Institute Homepage, and here’s a link to NASA Planet Quest: Finding Life.
Exobiology (same thing as astrobiology) is about life in space (on other planets, and moons; in other solar systems): where it is, what it is, how it started, and how it evolved (all studied scientifically, of course). Because the origin of life right here on Earth, and its early evolution, is essentially unknown, and because of the distinct possibility of similiarities with the origin (and early evolution) of life elsewhere in the universe, exobiology includes research into abiogenesis (and early, and extreme, life on Earth).
Exobiology is very much a multi-disciplinary field, drawing on biology, chemistry, geology (and planetary science), physics, and astronomy.
Because we have a sample of just one – life on Earth – it is difficult to make anything but the most general decisions on what lines of exobiology research are likely to be productive (keep in mind that null results can, of course, be quite productive). Conservatively, looking for planets like Earth in orbit around stars like the Sun (in age as well as mass, metallicity, etc), and looking for clues for fossil life in planetary environments like those found today on Earth (e.g. early Mars) seem better options than investigating possible silicon-based life (to take just one example).
As the number of exosolar (or extrasolar) planetary systems known continues to grow, quickly, discovering the prevalence of Earth-mass planets, in goldilocks orbital zones, seems like a good idea … so today we have the Kepler mission and COROT.
Less conservatively, the discovery of life around black smokers and sites like Lost City (not to mention entire ecosystems within crustal rocks … several km beneath the surface) sparked interest in the possibility of life in Europa, on Titan, even Enceladus (life – albeit rather simple life – we now know does not need to depend, ultimately, on the Sun’s (or another star’s) radiant energy … think chemolithoautotrophs).
Did you know that NASA has an exobiology branch? Check it out! Duke University’s Chemistry Department has an interesting Introduction to Exobiology you might find interesting too.
Multiple missions have been sent to Mars with the hopes of testing the surface of the planet for life – or the conditions that could create life – on the Red Planet. The question of whether life in the form of bacteria (or something even more exotic!) exists on Mars is hotly debated, and still requires a resolute yes or no. Experiments done right here on Earth that simulate the conditions on Mars and their effects on terrestrial bacteria show that it is entirely possible for certain strains of bacteria to weather the harsh environment of Mars.
A team led by Giuseppe Galletta of the Department of Astronomy at the University of Padova simulated the conditions present on Mars, and then introduced several strains of bacteria into the simulator to record their survival rate. The simulator – named LISA (Laboratorio Italiano Simulazione Ambienti) – reproduced surface conditions on Mars, with temperatures ranging from +23 to -80 degrees Celsius (73 to -112 Fahrenheit), a 95% CO2 atmosphere at low pressures of 6 to 9 millibars, and very strong ultraviolet radiation. The results – some of the strains of bacteria were shown to survive up to 28 hours under these conditions, an amazing feat given that there is nowhere on the surface of the Earth where the temperatures get this low or the ultraviolet radiation is as strong as on Mars.
Two of the strains of bacteria tested – Bacillus pumilus and Bacillus Nealsonii – are both commonly used in laboratory tests of extreme environmental factors and their effects on bacteria because of their ability to produce endospores when stressed. Endospores are internal structures of the bacteria that encapsulate the DNA and part of the cytoplasm in a thick wall, to prevent the DNA from being damaged.
Galletta’s team found that the vegetative cells of the bacteria died after only a few minutes, due to the low water content and high UV radiation. The endospores, however, were able to survive between 4 and 28 hours, even when exposed directly to the UV light. The researchers simulated the dusty surface of Mars by blowing volcanic ash or dust of red iron oxide on the samples. When covered with the dust, the samples showed an even higher percentage of survival, meaning that it’s possible for a hardy bacterial strain to survive underneath the surface of the soil for very long periods of time. The deeper underneath the soil an organism is, the more hospitable the conditions become; water content increases, and the UV radiation is absorbed from the soil above.
Given these findings, and all of the rich data that came in last year from the Phoenix lander – especially the discovery of perchlorates – continuing the search for life on Mars still seems a plausible endeavor.
Though this surely isn’t a confirmation of life on Mars, it shows that even life that isn’t adapted to the conditions of the planet could potentially hold out against the extreme nature of the environment there, and bodes well for the possibility of Martian bacterial life forms. The LISA simulations also indicate the importance of avoiding cross-contamination of bacteria from Earth to Mars on any scientific missions that travel to the planet. In other words, when we finally are able to definitively test for life on our neighboring planet, we don’t want to find out that our Earth bacteria have killed off all the native lifeforms!