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Stromatolites: Astrobiological Implications

Oil companies involved in astrobiology? It doesn’t seem likely, but in a roundabout way, it’s true. A consortium including Chevron, Repsol, BP and Shell have a natural interest in developing better models for subsurface reservoirs and source rocks in microbe-rich carbonate environments. At the same time, NASA’s Astrobiology Program is intrigued with how we could find bacterial structures on other worlds, and their role in planetary habitability.

The result: Both Big Oil and NASA are supporting research into stromatolites, the calcium-carbonate rock structures built up by lime-secreting bacteria (technically, cyanobacteria, that draw their energy from photosynthesis). We can probe ancient life on Earth by studying these accreted structures, some of which go back more than 3.5 billion years.

Erica Suosaari works for Bush Heritage Australia, an organization involved in conservation and land management. The Hamelin Station Reserve in Western Australia borders a nature reserve with vast quantities of marine stromatolites. Suosaari’s work in the area, funded by the above sources, is encapsulated in a paper in Scientific Reports (citation below), as noted in an article in Astrobiology Magazine, from which this:

“Looking for evidence of life in the rocks is like finding a needle in the haystack,” wrote Suosaari in an e-mail. “If stromatolites have definitive bio-signatures — such as self organized morphologies that are indicative of life processes — then it may be possible to look for that ‘signature’ in rocks on the surface of other planets and significantly reduce the size of that haystack.”

The Hamelin Pool Marine Nature Reserve offers stromatolites in extraordinary abundance, providing the opportunity to study analogs to the earliest such formations on Earth. Suosaari and team have discovered that modern stromatolites in their sample have created structures similar to stromatolites that emerged billions of years ago. The cyanobacteria that formed ancient stromatolites are believed to be the first organisms to use photosynthesis, with the significant side-effect of producing the oxygen so useful in the development of complex life.

Stromatolites_in_Sharkbay

Image: Modern stromatolites in Shark Bay, Western Australia. Credit: Paul Harrison (Reading, UK) using a Sony CyberShot DSC-H1 digital camera., CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=714512

Is Hamelin Pool, then, a window into the early Earth? The processes at work here involve microbes that draw from the same lineage, with the same oxygen-producing result. What’s intriguing for research in the near-term is that it may be possible to transplant microbial communities like these to other places. Let me quote from the conclusion of the Astrobiology Magazine article:

Suosaari said she thought of stromatolites when reading about SpaceX founder Elon Musk’s plans to bring life to the planet Mars. She suggested that because these stromatolite-building microbial communities produce oxygen, they could potentially make the Red Planet more life-friendly.

“Obviously with Elon Musk’s plans, we don’t have billions of years to shape the atmosphere if he is planning to move life there in the coming years, and Mars has less than 1 percent of the atmosphere of Earth,” she acknowledged. “But I begin to think about photosynthesizing microbial mats and how they have prevailed for billions of years; it’s a kind of resilience and longevity that our species hasn’t yet achieved. Perhaps we should look to these microbial communities to generate oxygen on the Red Planet at a small scale.”

An intriguing thought, as is the idea that fossil evidence of life on far more distant exoplanets may eventually tell our probes something about how life took hold there. In the case of Earth-based stromatolites, we see microbial mats that colonize the surface of the structure, mats that vary according to where the stromatolite is situated in the tidal zone. Consider the stromatolite as a record of previous surface mats, while the shapes of the various kinds of stromatolite relate to differing conditions in the broader pool.

This is an evidently global record, if we can learn to read it. Note this from the paper:

New insights regarding stromatolite growth in Hamelin Pool present opportunities for comparative sedimentological research advancing understanding of early Earth. The diversity of morphologies in the eight Stromatolite Provinces… provides a unique opportunity for investigating environmental and/or biological processes determining stromatolite morphology…. Of particular note, previously unreported, elongate nested subtidal structures of Spaven Province are remarkably similar to 1.9 billion year old longitudinal stromatolites at Great Slave Lake, Northwest Territories.

Could we find structures like these on distant planets? I’m reminded of the enigmatic ‘stolid, dark tower images’ returned to Earth by AXIS, a probe sent by a future Earth to Alpha Centauri B in Greg Bear’s Queen of Angels (1990). The AXIS data convince some that an intelligent life-form must have created the towers, but later the view shifts:

“The only news we have from AXIS may or may not be significant. A recently received analysis shows that at least three of the circular tower formations discovered by AXIS on Alpha Centauri B-2 are made up of mixes of minerals and organic materials, the minerals being calcium carbonate and aluminum and barium silicates, and the organic materials being amorphous carbohydrate polymers similar to cellulose found in terrestrial plant tissue. AXIS has told its Earth-based maters that, in its opinion, the towers may not be artificial structures…”

With knowledge of life’s development limited to our own planet, we can’t yet know what kind of structures are implicated in the development of life elsewhere, allowing habitable conditions to gradually develop. But we may eventually find structures just as rich in their own way as the stromatolites at the Hamelin Pool Marine Nature Reserve, and as enigmatic as the formations the orbiting AXIS probe investigates from its perch high above a habitable Centauri planet.

The paper is Suosaari et al., “New multi-scale perspectives on the stromatolites of Shark Bay, Western Australia,” published online by Scientific Reports 3 February 2016 (full text).

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Comments on this entry are closed.

  • Alex Tolley August 10, 2016, 15:56

    The astrobiology article seems like a stretch to me. If we are going to look for stromatolites in the geology of other worlds like Mars, we already know what to look for, just not necessarily where to look. Studies of living stromatolites on Earth might help in that endeavor, or maybe not. What we do need is a way to recognize these structures while doing surveys. The faces of cliffs and crater walls that show the stratigraphy might be the way to go, using an aerial vehicle to phtograph, analyze the patterns and perhaps take samples to confirm the findings. I don’t think we have equivalent environments anywhere in the solar system to look for living stromatolites or their analogs, so recognition of living stromatolites on exoplanets is going to be a bit pointless.
    As for terraforming Mars, even if that is a good idea, using cyanobacterial mats is probably not the way to go. Algae would be better. For a world as dry on the surface as Mars, engineered lichens might be the best way to spread those photosynthetic algae first. Later, bodies of water would be possible algal habitats, either in the open or protected under tent enclosures. Similarly for an enclosed life support system for martian colonies or cities. For purely aesthetic reasons, I would expect terrestrial plants, possibly engineered, would be common in those colonies as part of the atmosphere recycling. However, it wouldn’t surprise me if artificial means of atmosphere recycling were used, perhaps mimicking photosynthesis, but as more controllable chemistry.

  • John Kavanagh August 10, 2016, 22:28

    geobiologist Nora Noffke at Old Dominion University has an hypothesis around the possible microbiological origin of some sedimentary features observed by Mars Curiosity.

    http://www.astrobio.net/news-exclusive/potential-signs-ancient-life-mars-rover-photos/

  • Brian A Schmidt August 11, 2016, 0:51

    Curious why fossil fuel companies care about carbonate rock – maybe as a potential for carbon sequestration?

    Regarding stromatolites and astrobiology, Mars is by far the obvious place to look. Maybe the stromatolite structure could show up though in a different function, like a non-photosynthetic, microbial community clinging to the underside of the ice layers on Europa or Enceladus. Maybe some fragments of those would be visible to a future lander (or eventually, a submarine).

    • Jim Baerg August 17, 2016, 0:57

      As reservoirs that can currently hold petroleum & natural gas.

  • djlactin August 11, 2016, 10:35

    (1) For billion years, they were the apex of evolution, until their pollutant favored the evolution of their conquerors. [insert sci-i scenario here].

    (2) Thromolites: https://en.wikipedia.org/wiki/Thrombolite

    (3) Stromatolites require water, so they are not promising as terraforming agents for Mars. However, fossils would be unequivocal evidence of … something (I’m not sure what).

    • ljk August 11, 2016, 12:56

      Mars used to have lots of water, and there’s lot of subsurface water ice now.

      http://www.space.com/30502-mars-giant-ice-sheet-discovery-mro.html

      • Michael T August 12, 2016, 4:28

        Yes I was wondering about the water issue too. if water could be pumped up from below, stormatolaites at least seem to be tough, so might be able to survive. you’d have to start in some low-lying area where liquid water wouldn’t evaporate quite so quickly, say in the bottom of Valles Marineris.

        Michael T

        • ljk August 12, 2016, 8:55

          And we could transport the water to the human colonies across the Red Planet by using… canals.

          • Michael August 12, 2016, 17:37

            If the pressure was great enough we could ;)

            • Michael T August 13, 2016, 13:12

              Yes.

              Open canals don’t work well in places with lots of evaporation.
              Pipes would maybe be less work than construction of canals, and some water would actually get from A to B!

              Still, canali or rivers with hrossa and hnakra living in them (See CS Lewis) would be nice to have, when the atmospheric pressure was good enough :-)

  • David Cummings August 11, 2016, 11:56

    I’m looking forward to Mars 2020.

    https://en.wikipedia.org/wiki/Mars_2020

    It will be well equipped to look for biosignatures on the Red Planet.

    • ljk August 12, 2016, 9:30

      I thought Curiosity was also equipped to do this? What is the difference between the two rovers in this regard?

      Why does NASA keep pushing the whole life on Mars thing down the road? Ever since Viking came back with supposedly ambiguous results, the space agency has danced around the issue. When Viking was sent to the Red Planet we had different ideas about what native life forms might be like on Mars. Now we know better thanks to direct exploration, which is what such science missions are all about.

      Instead the misconception that the twin Viking landers had to find solid evidence of alien microbes right off the bat (or lichen or even something crawling in front of its cameras) or the mission was a failure haunts NASA’s visions for Mars exploration to this day. Why do you think they did not send another lander to Mars for almost twenty years after Viking?

      There are other spacefaring nations that will not be under such cultural and historical misapprehensions when it comes to finding life on Mars, either alive or as fossils. Will this become another area where NASA and the USA had a chance to do another space first yet let it slip to a rival? If that is what it takes to advance science knowledge and one of the most important questions ever (does extraterrestrial life exist?), then so be it.

      Already SpaceX is talking about putting humans on Mars as early as 2025 with their Red Dragon spaceship and Heavy Falcon rocket, while NASA continues to place their manned Mars plans vaguely in the 2030s and are relying on a spacecraft (Orion) and rocket system (SLS) where the latter hasn’t even had one test launch yet:

      http://www.spaceflightinsider.com/organizations/space-exploration-technologies/cost-details-revealed-spacexs-red-dragon-mission/

      And as for other nations wanting to be the first to find alien life, this is not some hypothetical. China has officially declared that one of the main goals for its new FAST radio telescope, the largest single dish on Earth, is to help China become the first nation to find ETI.

      https://techcrunch.com/2016/07/05/china-invests-in-the-hunt-for-aliens-with-worlds-largest-radio-telescope/

      http://phys.org/news/2016-07-china-world-largest-radio-telescope.html

      China could also do one heck of a radio METI program with FAST. For those who oppose METI, if China wanted to broadcast messages into the Milky Way galaxy with their giant new toy, who would be able to stop them? Perhaps those who declare themselves in charge of such things should be already thinking about talking with China and anyone else with similar capabilities in regards to METI if they are serious in regards to monitoring and controlling what kind of messages humanity will be lofting into the unknown. Or will, as usual, such talks happen only after China or someone else starts doing some serious METI on their own without asking anyone else first?

      Exactly how together is the SETI community on this matter? I know Breakthrough Initiatives is dealing with the subject, but of course at the moment it is all academic:

      https://breakthroughinitiatives.org/Initiative/2

      Which just means there will be groups and even nations who will resent being told what they can or cannot say to the rest of the Universe by a small selected group of elites and will do their own METI. And one of those “rebels” could very likely be China.

  • tchernik August 11, 2016, 15:23

    I vividly remember Queen of Angels, and the pity I felt for AXIS.

    For context, the novel depicted AXIS as the first fully self aware computer, reaching such state in a planet far away around Alpha Centauri.

    AXIS really wanted to find intelligent life there, to fulfill its mission and … probably to have someone to talk to that wasn’t 4 light years away. Greg Bear really shines by noticing computers are designed to interact with their users (finding what we would call ‘purpose’ in it), and having one becoming sentient in the most lonely place imaginable makes such situation an unusually cruel fate for any sentient being.

    So probably AXIS’s discoveries were biased by that fact, and they also happened shortly before having literal psychotic breakdown.

    The allegories I see with our ardent desire to see some patterns in the chaos and to find someone out there are rather unnerving, because we can also make the same mistakes.

    • ljk August 12, 2016, 10:18

      Assuming we need an Artilect with self-awareness to pilot an interstellar mission (if the starship has an Artilect for a “brain”, does that make the whole vessel its body?), have those who are designing such missions taken into account how such a being might feel about being sent light years across deep space to an alien star system with no prospect of ever returning to Earth or going anywhere else after that?

      I am guessing not really outside of science fiction and a few late night gab fests at some local pizza place. And Centauri Dreams. :^)

      Case in point: The BIS team that developed the Daedalus interstellar probe in the late 1970s said the computer brain for the vessel should be “semi-intelligent” (they suggested a similar state for the computer brains of the Wardens). Whether that implies being conscious or not to perform independent tasks as it must was not made clear. In any event, the team did make clear that Daedalus would be left to drift off into the galaxy after its all-to-brief mission through the target star system (Barnard’s Star at the time because it was thought to have several exoplanets).

      Other than monitoring interstellar space conditions for as long as it could function (just like Pioneer 10 and 11 did and Voyager 1 and 2 are doing after their main planetary missions were complete), Daedalus would have nowhere else to go and nothing else to do mission wise. The probe would not even be able to stop in its target system due to its 12% light speed velocity.

      If you were an aware being who knew in advance that you would spend decades traveling through deep space for a goal that you would literally only spend hours at, then spend the rest of your existence drifting among the stars again alone with no hope of rescue or even another science goal, how would you respond?

      I hope the folks who build these star vessels take such things into consideration. This is why we need more than just engineers on all interstellar missions, robotic or otherwise.

      Any serious literature on the subject available?

      • Alex Tolley August 15, 2016, 11:22

        The artilect’s sense of time does not need to be constant. During flight its systems could slow down so that time is perceived to have sped up. Conversely, during encounter, the systems are sped up, so that the artilect perceives the event as taking a long time.

        This might make journeys far more acceptable to machine intelligences.

        If not, ensure that they are not self aware, and the problem is solved.

        • ljk August 17, 2016, 10:55

          But what if you NEED self-awareness in order to function independently as an interstellar probe will require? And what if the Artilect later discovers it has been tricked regarding this whole time dilation business? Remember what HAL 9000 did when it was told to lie to Bowman and Poole about the true purpose of the Discovery mission? The authorities who set up the mission in 2001 clearly did not consider the psychology of an Artilect and several human astronauts paid the price for that oversight later.

          And time trickery or not, if we send a self-aware probe on a one-way mission where it will be sent drifting off into the galaxy with no other purpose (except maybe monitoring interstellar space for decades, which might be fun for the Voyagers but their computer brains just ain’t that smart – V’Ger excluded) indefinitely, will a self-aware being want to go on such a quest just to make a few distant organic beings temporarily happy so they can publish papers and advance their academic careers?

          How many AI specialists are really looking into these aspects of Artilects? I know AI is being worked on so this is not just some fantasy, but how many of these researchers are really asking such questions regarding consciousness and awareness and emotional states? Especially for minds that could easily exceed human brains in every way? Or will we just ignore this until something goes very wrong? With a mind that can vastly out think humans and will not be bogged down with or by our numerous limitations?

          Ever see the vastly underrated and ignored science fiction film from 1970 titled The Forbin Project:

          http://www.charlestoncitypaper.com/charleston/1970s-colossus-the-forbin-project-is-more-relevant-than-ever/Content?oid=6112034

          • ljk August 17, 2016, 11:18

            No offense to you, Alex Tolley, but that is what bothered me about your comment to my initial inquiry: Not to investigate the psychological state and parameters of an Artilect destined to go on a long journey into the void with only a brief purpose, but instead let’s trick it so that the Artilect/Ship will do our bidding so that if it ever does figure out it will be left drifting indefinitely in interstellar space, it will be too late to do anything about it.

            I am suddenly thinking about this line from Jurassic Park:

            Dr. Ian Malcolm: “Yeah, yeah, but your scientists were so preoccupied with whether or not they could that they didn’t stop to think if they should.”

            I am all for exploring other star systems. I am just concerned that one of the key piece of such a mission will be overlooked while most everyone involved seems so focused on the structural and propulsion engineering parameters of a star vessel, which is certainly understandable, but there are other factors which must be taken into account or such a mission will never happen. The psychology of a self-aware Artilect is one of them. And I ask again: Do we know we can create a mind that can think independently without requiring consciousness in order to actually work?

            Just as when we first started lobbing actual human beings into space, the space agencies mainly cared that no one died or publicly embarrassed them over their psychological needs. That may (or may not) have been fine back in the Right Stuff days when a couple of macho men only had to endure a few days in their tin cans, but things are certainly changing now, especially since there is finally serious talk about manned lunar and Mars expeditions and colonies which will last years and longer. NASA is still trying to catch up from these decades of benign neglect. See here for the evidence:

            https://www.centauri-dreams.org/?p=24523

  • ljk September 1, 2016, 9:18

    If life could exist on Earth 3.7 billion years ago, this does improve the chances for there being life on many other kinds of worlds, including ones we might currently consider hostile to organic creatures:

    http://www.livescience.com/55950-worlds-oldest-fossils-found-in-greenland.html

    To quote:

    Both Kamber and Allwood also said the new findings have implications for the field of astrobiology and the search for evidence of past life on other planets — particularly on Mars.

    Kamber said these potential clues about the very early emergence of life on Earth in the Hadean period supports his own recent research, published earlier this year, about the prospects for life in the water-filled craters caused by meteorite and comet impacts on the early Earth.

    “I think the enclosed impact basins at the tail end of the bombardment at 3.8 [billion] to 3.85 billion years ago would have made great places for life to emerge from,” he said.

    Allwood added that there is also clear evidence that, at the time the rocks at Isua were forming 3.7 billion years ago, conditions on Mars were similar to those on early Earth.

    “[T]here were similar environments in bodies of water standing at the surface of Mars, offering a similar kind of environment to the ones that hosted the early evidence of life on Earth, at Isua and younger,” she said.

    Until now, there had been a gap between the start of the fossil record on Earth and the youngest areas on Mars, where there was good evidence for standing bodies of water in the past.

    “And you had to imagine that life could have arisen there before they dried up — but now at least we may have one example in the fossil record showing us that life can arise that quickly,” Allwood said.