Mars Phoenix solves two mysteries with one ion

By Phil Plait | September 6, 2010 7:00 am

marsphoenixIn the late 1970s, NASA landed two probes on the Martian surface. The Viking missions were designed to scoop up surface material and examine it for indications of life.

What was expected was for the missions to detect organic compounds: carbon-based molecules like amino acids that make up the building blocks of life. Instead, the results they got were disappointing. Instead of organics, they found compounds of chlorine like chloromethane and dichloromethane, which were interpreted as contamination from labs back on Earth (from cleaning fluids!).

perchlorateHowever, in 2008, the Mars Phoenix lander did its own scooping, and found something unexpected: perchlorate. This molecule is made up of one chlorine atom and four oxygen atoms (ClO4) and has the interesting property of being very reactive with organic molecules. It’s found naturally on Earth, too.

What’s so very interesting about this is that recently, scientists took samples of soil in Chile, added perchlorate, and then analyzed those samples in the same way Viking did. Guess what they got?

Yup: chloromethane and dichloromethane.

So what does this mean? Well, it would solve the Viking mystery! The chemicals the Viking landers detected more than 30 years ago may have been the result of organics in the Martian soil reacting with naturally occurring perchlorates. That would explain why there were no organics, as well as the chemicals they did find.

Mind you, this does not mean Mars has life. But it does mean that if organic molecules are on Mars — and we expect them to be; for one thing they’re commonly found in meteorites on Earth, which would hit Mars as well, and many organic compounds are created relatively easily naturally — then they may get zapped by perchlorates.

So it’s still possible that Mars may have the precursors for life on or near its surface, but not likely where perchlorates are hanging out. If perchlorates are common this may make it less likely for us to find complex organic molecules. But we should note that the presence of chloromethane and dichloromethane implies that organic molecules did once exist there!

Again, this doesn’t mean life, but it does mean that conditions on Mars were once able to support the presence of organics. The search for life, extant or extinct, on Mars is like a giant jigsaw puzzle, and one more piece has been placed in it. There’s still perhaps a long way to go, but every step gets us a little closer.

Image Credit: NASA/JPL-Caltech/University of Arizona, Wikipedia Commons

CATEGORIZED UNDER: Astronomy

Comments (47)

  1. jeromeclemente

    thats cool. we need a big leap to discover one of the universe’s deepest secrets. thats why we need to explore mars, more than technology, we need political will. go phil, nice article

  2. kevbo

    So where (and when) did the perchlorate come from? Is it, relatively speaking, a newcomer? Or would it have been around long enough ago to have toasted any organics back when water might have been around?

    I guess rather than simply ask, I should do sum thinkin an readin….

    OK, from wiki:

    “In 2006 a mechanism for the formation of perchlorates was proposed which is particularly apropos to the discovery of perchlorate at the Mars Phoenix lander site. It was shown that soils with high concentrations of natural salts could have some of their chloride converted to perchlorate in the presence of sunlight and/or ultraviolet light.”

    Post-water it is! (and the read on wikipedia on perchlorates is pretty interesting. go on – try!)

  3. Adam

    Thanks for posting this Phil,

    I’ve always suspected the “contamination theory”of the viking mission wasn’t really contamination. Just scientists unwillingness to publish something so groundbreaking, without repeated confirmation.
    I’ve repeatedly told friends that there is more to the amino’s on Mars, and we’re up for a big discovery. I was a little nervous when the phoenix didn’t pick anything up immediately.

  4. Gary Ansorge

    If the perchlorates result from UV, then Europa or Titan may have a much better chance (due to distance from Sol and thick, protective atmospheres)of retaining amino acids detectable to our instrumentation.

    Now, all we need is a nuc powered space craft to transport and land a multi ton robotic explorer and begin the search.

    I am SO anticipating the demise of religiously based antipathy to life beyond this earth(this is not to imply that ALL religious people have such antipathy, just the nutters,,,).

    ,,and the solution to the Fermi Paradox?

    1) we’re property, so no one is allowed to drop in and say hi.
    2) Who owns us? Probably a gene salesman,,,as in, “get your survival genes here. Developed and tested for 10 million years in the harshest and most competitive life environment known.”

    Gary 7

  5. Messier Tidy Upper

    Well done Phoenix rising to the challenge again! ;-)

    That awesome little probe may be gone – buried and crushed beneath the snows of Mars but it certainly isn’t forgotten. 8)

    I did read somewhere (one of the popular science mags, forgotten which) that this chemistry was postulated along with the suggestion that the Viking tests not only found life – they killed it too as a result of miscalculating this martian chemistry. D’oh!

    @4. Gary Ansorge :

    …the solution to the Fermi Paradox?
    1) we’re property, so no one is allowed to drop in and say hi.
    2) Who owns us? Probably a gene salesman,,,as in, “get your survival genes here. Developed and tested for 10 million years in the harshest and most competitive life environment known.”

    Except I doubt our environment is anywhere near the harshest and most compeditive out there. That violates the principle of mediocrity and we know of potentially harsher environments and planets that have possibly have life or at leats semi-plausible speculations of life.

    Serious suggestions have been made for life in the upper cloud layers of Venus, of life in the oceans of Enceladus, of life on the surface of a sun-like star, in nebula and even the surface of a neutron star. How much is SF and how much actually in existence is another question but still.

    Besides if we’re property (nice idea that!) then are we a good investment? Are we “maturing” and rising in worth like aging wine or devaluing ourselves like a second hand car at a demolition derby? How can we (or they?!) know if we’re not evaluated periodically? ;-)

    What use are we as property? Entertainment? Storage? Food? Lab rats? All the above? Something else entirely?

  6. Happy Camper

    Am I the only one who thinks that we are way past due to launch Mars sample return missions?

  7. Pat

    I always assumed the solution to the Fermi Paradox is that the universe is freaking huge. The Andromeda galaxy next door could hold an interstellar empire and we might not detect a hint of it for another few million years. With all the galaxies out there, what are the chances intelligent life is all clustered in conveniently close proximity?

  8. Gary Ansorge

    5. Messier Tidy Upper

    Granted, Earth isn’t the most difficult ecological environment(life on the sun? Guess you’ve read Sundiver by David Brin???) but from the standpoint of competitive survival of DNA based organisms, it’s pretty harsh.

    Data storage is one possibility, something else entirely is more likely. Food; not at all likely. Easier for an advanced civilization to grow meat with exotic textures, flavors, etc in a vat. Entertainment? Yeah. I love Monty Python too.

    Intelligence is one thing(we already have some very “intelligent” AI expert systems), sentience is perhaps quite another. I have a feeling many humans fall far short of the latter,,,but we’re getting there.

    Something else entirely? Perhaps the biggest problem with a civilization that’s been around for several million years, is ennui and breeding for complacency( as in, jail all the aggressive, survival prone problem folk, leaving only the acquiescent ones to breed. Good for social stability but very bad for the long term survival of the species). We need controlled aggressiveness to enable us to survive in the face of the unexpected. After all, the universe is quite good at presenting challenges and it really seems at times that it is oriented toward killing us.
    Most humans will persevere and try to survive in the face of overwhelming odds. Those who had such survival genes are the reason we’re still here. Had they been wimps, we’d not be sitting here today. I often wondered(as a kid) why those faced with overwhelming pain and sorrow kept on keeping on. I think it’s genetic,,,and those genes might be of great value to a really old species. Might be the only thing that would keep them from just lying down and becoming extinct.

    Gary 7

  9. Messier Tidy Upper

    @6. Happy Camper :

    Well there is one planned in case you hadn’t already heard :

    http://en.wikipedia.org/wiki/Mars_Science_Laboratory

    &

    http://marsprogram.jpl.nasa.gov/msl/

    As for way past due, I think its way past due that we had people on Mars – & given its 2010 ( http://en.wikipedia.org/wiki/2010:_Odyssey_Two ) – orbiting Jupiter too! We’re way behind schedule if you ask me. ;-)

  10. John Sandlin

    One wonders how these results might affect future plans for colonization. Doesn’t sound like Martian soil will make good garden soil.

  11. Messier Tidy Upper

    @ 10. John Sandlin :

    Actually, if I’m remembering correctly, the Phoenix tests led early on to one of its scientists saying you could grow asparagus quite well in Martian polar soil as studied by that lander. Of course the frost and chill temperatures generally might make things a little hard, not to mention the thin air and reduced sunlight with extra strong UV but still .. ;-)

    @ 8. Gary Ansorge :

    (life on the sun? Guess you’ve read Sundiver by David Brin???)

    Yes indeed – & Ben Bova’s Venus (part of his Grand Tour series) :

    http://en.wikipedia.org/wiki/Venus_(novel)

    and Fred Hoyle’s The Black Cloud :

    http://en.wikipedia.org/wiki/The_Black_Cloud

    plus Olaf Stapledon’s Nebula Maker and Stephen Baxter’s Flux :

    http://en.wikipedia.org/wiki/Flux_(novel)

    Robert Forward’s Dragon’s Egg and more among my faves. Love Monty Python too. :-)

  12. John Sandlin

    With all due respect to Fermi and his paradox, I tend to think along the following lines:

    For the complex technology we use, and even more complex technology of the hypothetical aliens, several iterations of star birth and, more importantly, spectacular death were required to create all the heavy elements. So the first stars had no rocky planets but began the process to create the needed materials. How many iterations would that take? I have no idea – perhaps it’s quite a long while. So perhaps for a few billion years, the universe was insufficiently dirty for technology.

    Life in general probably exists all over the place now, but we can note in our own planetary history the frequency of life being nearly wiped out in planet-wide events and note that our experience is likely not unique, so the process toward a technological civilization is also slow due to having to restart periodically. So perhaps another few billion years, no one is smart enough for technology. Then there’s the question of being able to divert disaster once technology becomes possible. A planet killer asteroid in the next few dozen years would put an end to us. A technological civilization would need to survive its birth.

    I think Fermi under estimated the resources required to launch galactic probes to all corners of the universe and the superior technology required to make probes that would last the millions or hundreds of millions of years it takes to cross the vastness between stars. Each of these mechanically perfect probes (how else could they last the ages) would need to be mining, refining, refueling, repairing, manufacturing robots – and huge. Mine the comets and asteroids for resources to send out the next wave of probes. To what end?

    Like our own governments, the desire to send the probes would likely meet resistance and need justification. What would be the benefit? No, better to spend the resources locally would be the typical response. Just look at our own space programs.

    Unless there are unexpected breakthroughs in physics that change rocket technology, every thing needs fuel to speed up and slow back down. You can either, as our probes have been doing, just barely exceed the local escape velocity so that the fuel required to slow is minimal but travel times are immense or travel times are short by reaching incredible velocities but huge amounts of fuel are required to speed up and slow down (and by short we mean the travel times are still immense).

    So, why aren’t there alien space probes all over the universe? Economics.

    Perhaps they are crawling all over the universe, we’ve only been interesting for the last few microseconds (galactically speaking), give them time to notice us. But I bet they’re still at home working on maintaining their own survival locally.

  13. Gary Ansorge

    12. John Sandlin

    As I’ve contended before, despite the Principle of Mediocrity, we may just be the “special ones” who are the first to get this far, technologically speaking.

    If we ARE the first of the Ancient Ones, I feel really sorry for those late comers. By the time they get to space, we’ll own it all.

    ,,,or at least, BP will,,,but I’m sure we’ll be really wise, as we exploit the galaxy.(snark)

    Gary 7

  14. John Sandlin

    I agree on the Principle of Mediocrity, Gary. Even if everyone were essentially the same, some one still has to be first. I’m not inclined to argue that we are – but certainly I allow for it. Like I said with my “few billion years” notes, maybe it just takes 13.7 billion years to create a baby technological civilization like us.

    Even if we aren’t first, maybe we’re in the first few millions of such civilizations and no one had the time. Of course, that assumes that in these first few millions someone has the gumption to try.

  15. Gary Ansorge

    14. John Sandlin

    “Gumption” is probably the exact right word for this. My Son contends that virtual reality is probably the real reason we’ve not been visited. Everyone in those “other” techno civilizations is quite happy to live in a “perfect” environment and have no desire to go anywhere.

    I hope he’s wrong but I’m not inclined to bet against him(He’s a LOT smarter than me).

    Gary 7

  16. HvP

    Gary and John,

    C’mon, we all know that the Earth is simply the largest computer ever built, commissioned by mice to use a biological algorithm to find out the ultimate question for the meaning of life, the universe, and everything.

    (um, did anyone notice that big yellow thing in the sky?)

  17. Chris Winter

    So is this partial vindication for Gil Levin, or final falsification?

    AIUI, in the Viking experiments, the organics were added to the Martian soil. Thus, in his Labeled Release experiment, the “soup” added to the soil was oxidized by perchlorates, generating the carbon dioxide which the experiment detected.

    http://www.gillevin.com/

  18. samsam

    Gary, John

    Progress in physics seems to indicate that reality is further and further from what our monkey brains think reality is.
    Any civilization that has learned enough to achieve effective interstellar travel may have decided that traveling through 4-D spacetime just doesn’t offer very many interesting sights.

    Not trying to sound mystical here, but 100 year old quantum mechanics is pretty weird. What will we find in the next 100?

    Samsam

  19. Happy Camper

    @9. Messier Tidy Upper :

    Just a little background so you can understand where I am coming from. I am old enough to remember hearing the first sputnik on my dads ham radio. I can also remember watching the echo satellite pass overhead. I was inspired by watching the grainy black and white TV broadcast of Freedom 7 putting Alan Shepard into space. Later I watched the Apollo launches from my front porch and worked in the aerospace industry.

    I am disappointed with the space program overall and have about the same position as Dr. Robert Zubrin of the Mars Society. The shuttle (although pretty neat)never really lived up to its promise of being a low cost solution to space flight. Instead it became the most complex and expensive flying machine ever built not mention most complex and expensive spacecraft. I would have guessed that we would have been on Mars at least 25 years after Apollo. In the mid 70’s I would have thought that we would have moon bases by now and even a Mars base. The fact of the matter if we had devoted 10% of the defence budget we would likely be very close to those ideals. But there is no political will to get these things done.

    Now the Viking landers were launched in 1975 if my memory serves correct and a sample return mission would have been possible within 10 years of that had there been the will to do so. I have known about the Curiosity mission for several years now and looks like a very capable design (about 15 years late) but there is nothing like returning a sample. Not only do you get a rock or soil back but it also works as a technology demonstrator.

    I am in favor of a robust manned and unmanned space program. Unfortunately it appears far too many people are anti science and are more interested in looking to the good old days rather than looking to the future.

  20. Mike Mullen

    Well if we are ‘behind schedule’ Viking probably played a large part in that because their results took a lot of the momentum out of Mars exploration. They essentially pointed to a dry, dead world and at the time nowhere else outside of Earth seemed a likely candidate, not exactly inspiring for future exploration.

  21. Anders Feder

    Phil, as I read it, it is not that it is “not likely” to find organics where perchlorates “are hanging out”. The perchlorate doesn’t react spontaneously with the organics. Rather, it was (hypothetically) the specific Viking experiment itself that caused the perchlorate to react and thus destroy the organics when it heated the soil and its perchlorate/organics content.

    MSL will have other ways to examine the soil in which this destructive reaction should not occur. This means that it is now fair to expect that MSL will find organics – they are not necessarily as rare on the surface as has been thought for 30 years.

  22. os

    Awesome news, in fact i’ved just arrived from the conference held by the leader of the investigation, Dr. Rafael Navarro Gonzalez from of the National Autonomous University of Mexico, Dr. Peter Smith of the Phoenix mission and Christopher P. McKay.

  23. Tyler Durden

    @#19, Happy Camper:

    Sadly I’m forced to agree with your statements in regards to the Shuttle. It is (was? well, soon enough we can refer to it past tense) the most complicated piece of technology ever built… sadly, most of that was overkill. It was not at all the vehicle we needed to construct a working infrastructure in Earth orbit. Complexity sometimes just means more things to go wrong.. and simple and stupid is sometimes the most effective tool for the job.

    The shuttle was a poor compromise between scientists and politicians – Congress demanded a reusable vehicle, so NASA delivered.. despite the fact that mostly un-recyclable vehicles could have done the jobs needed cheaper, and had the advantage of being able to adapt the design for those vehicles as technology improved and the tasks needed evolved.
    But it’s difficult to convince a politician that it’s cheaper and more effective to burn many tons of steel in the atmosphere than it is to build a reusable ship.

  24. Nigel Depledge

    Anders Feder (21) said:

    Phil, as I read it, it is not that it is “not likely” to find organics where perchlorates “are hanging out”. The perchlorate doesn’t react spontaneously with the organics. Rather, it was (hypothetically) the specific Viking experiment itself that caused the perchlorate to react and thus destroy the organics when it heated the soil and its perchlorate/organics content.

    MSL will have other ways to examine the soil in which this destructive reaction should not occur. This means that it is now fair to expect that MSL will find organics – they are not necessarily as rare on the surface as has been thought for 30 years.

    Chemistry still happens at low temperatures – the reactions between perchlorate and whatever organics there are will still occur at -20 or -40 °C but will be orders of magnitude slower than in the Viking expt. However, the products of that chemistry might be different, for reasons that I can’t think of a way to share in less than three paragraphs.

  25. Nigel Depledge

    @ Tyler Durden (23) –

    Don’t forget the military input into Shuttle’s specifications. Had it been left as a small launch vehicle rather than the monster it became, it may not have needed the ET and the SRBs.

    Of course, it would not then have been able to launch missions like Hubble, so there may have been more resistance to the orbiting observatories.

  26. Dunc

    the process toward a technological civilization is also slow due to having to restart periodically.

    Umm, no. Technological civilisation is not the “target” of evolution. Before we came along, life on Earth was not progressing towards anything – it was just muddling along (as it still is). If it wasn’t for those mass extinctions, we’d still have one of the previous stable ecosystems which did not feature technological civilisation.

    Then there’s the fact that we’ve been around in our current form for a very long time, but only developed our current technological civilisation recently. The ancient Greeks (or many others) could have developed all of the technology needed for the Industrial Revolution, but they didn’t.

    Neither the evolution of a species capable of developing technology, nor the actual development of that technology once such a species has evolved, are certain, or even particularly likely.

    To put it in terms of the Drake equation, both fi and fc are probably quite a lot smaller than 1. It quite possible that L isn’t very big either.

  27. Bob

    is there any new photos of the viking landers
    has the Mars Reconnaissance Orbiter taken photos of them?

  28. Gary Ansorge

    26. Dunc

    Granted, neither sentience nor technology are the “point” of evolution, they’re just patterns of mass/energy that happen to be successful at sustaining themselves.

    I believe it was the Greek Hero who built the first steam engine(ok, it was a ball of copper, heated over an open fire, that spun from steam vents). Unfortunately, it was the Greek ideal of intellect being superior to experimentation that guaranteed his experimentalist approach would not be acceptable to his fellows. There is a bias in the middle east toward getting ones hands dirty(experimental, actually building something), as in “Gentlemen don’t work for a living. They just provide supervision.” Romans weren’t so restricted, thus they became known as the builders of roads but they weren’t particularly oriented toward a theoretical understanding of processes. It took another millennium for someone(a Sufi mystic in Persia), to delineate the scientific method, which combined those two disparate approaches to knowledge. It took another half millennium for the law(as in protection of intellectual property rights) to allow individual inventors to profit from their labor. THAT’S when the industrial revolution took off. We had to get so many different things right before we could get a techno. civilization off the ground, I’m occasionally amazed we managed to do it at all.

    So, yeah, there may be a lot of intelligent, sophisticated species out there that just never managed to get all those ducks lined up.

    Gary 7

  29. John Sandlin

    @ 26 Dunc: I know full well that evolution doesn’t have a point or plan. Perhaps I left too many words out trying to fit an already long comment to a smaller space. It does seem likely that a species that develops technology will have an advantage over species that do not. So while not inevitable, technology is likely.

    First, however, you have to have the raw materials, no matter how intelligent your species.

    Then you have to survive.

    We may be one of the first. There is no paradox.

    Finally, we may not survive long enough to be first, either.

  30. Jamey

    @Pat – #7 – Sorry, but you’re *badly* underestimating growth rates. It comes down to the old question about algae in the pond – one algae the first day, doubles every day, pond’s half-full on day 29. When is the pond full? Hint – it’s not day 58. And day 31, you’re looking at 2 ponds (galaxies?) worth of algae.

    Any realistic growth rates, assuming some kind of interstellar transportation (even if it never makes better than 1/1000th of c) results in galaxies filled in a few million years, and the next galaxy over shortly there after.

  31. SLC

    Re John Sandlin @ #29

    A necessary, but not sufficient, condition for the rise of intelligence and hence technology is encephalization. There is evidence for a selection advantage for encephalization from the fact that the Cretaceous dinosaurs were more encephalized then their Jurassic forebears and that todays’ mammals are more encephalized then the mammals of 50 million years ago.

  32. John Sandlin

    A little back of the envelope math – just on travel time to cross the galaxy from our position 75,000 light years from the farthest edge (very roughly) shows the following:

    @c travel time is 75,000 years
    @0.001c travel time is 75,000,000 years
    @voyager speed (~16km/s) travel time is 1,395,000,000 years

    These would be the best rate numbers to fill the galaxy – assuming negligible failure rates for the probes. Regardless of the replication rate, you still have travel time. These are the numbers for average velocity and assume the time to build new probes at each new system is insignificant compared to travel time.

    Travel time to the Andromeda Galaxy
    @c travel time is 2,500,000 years
    @0.001c travel time is 2,500,000,000 years
    @voyager speed travel time is 46,500,000,000 years
    That’s just to get there.

  33. We haven’t been contacted by extraterrestrials yet because they’re all too busy updating [Alien]Book with their latest exploits on their home planet(s). :)

    Joking aside, I think Mars has a lot more to say. Missions to Mars excite the crap out of me. I really loved watching the coverage of Phoenix landing a couple of years ago. Hearing the speeds, altitudes and various key events. That was one happening control room. It was by far more exciting than any sporting event (save game 7 of the 1992 NLCS Braves vs. Pirates :D )

    I could watch space stuff all day!

  34. amphiox

    Slightly off topic here, and I’m not a chemist, but it occurs to me to wonder if, given that perchlorate is such a powerful oxidizer and so reactive, if it is abundant enough, could it be used as a source of fuel/energy for say a Mars mission to use to synthesize rocket fuel for their return trip, or for Mars colonists to use? A readily available fuel source that’s literally dirt cheap on Mars would go a long long way for the economics of Mars exploration.

  35. amphiox

    It has also occurred to me that the Fermi Paradox focuses primarily on the travel time between stars. But a technology capable of interstellar travel may not actually be all that interested, from an engineering/economic point of view, in planets. Which is to say they could be traveling from star the star widely, but be staying out in the Oort Clouds and Kuiper Belts harvesting the organics and volatiles they need from comets and dwarf planets and powering themselves with fusion (even assuming that their biological requirements are as stringent as our own). There would actually be a disincentive for them to waste the energy to descend deep into the stellar gravity wells to go to planets like Earth in any great number.

    While it is certainly plausible if not likely that they would be interested in planets like earth scientifically, such an interest would in fact motivate them to be discrete – they would spend most of their effort observing us with telescopes, and what expeditions they do send for direct visitations would be expected to be small and well hidden.

    Which brings up the question that if such activity were occuring in the Oort Cloud or Kuiper belt or therearounds, how likely would we be to detect it with our currently available astronomical techniques and instruments?

  36. amphiox

    Neither the evolution of a species capable of developing technology, nor the actual development of that technology once such a species has evolved, are certain, or even particularly likely.

    While I agree with the general principles in the rest of this particular post, I must point out that trying to use any probabilistic arguments with our current state of knowledge is actually not valid.

    The point is “[+/-not] particularly likely” with respect to what? What is the denominator of your (Technological Intelligence)/N for your probability assessment? All the data we can muster by studying life on earth and human history can only apply to N as number of species. And of course we know that this probability is very low.

    But for the question of extraterrestrial technological intelligences, we need to know what N is for number of planets. Any planet with an earth-like biosphere should be expected to produce trillions and trillions of species occupying trillions and trillions of every-changing niches over a habitable lifespan of several billion years. So even if the likelihood of intelligence per species is minutely low, from the point of view of the lifespan of an entire planetary biosphere, the probability could still easily approach unity (or not – all we can say is that our current experience is 1/1.)

    So what is the sequence of preadaptions/mutations that lead to technological intelligence? How many different ones are there (is the path that led to humans on earth the only way or not)? How likely are these events to occur? What are the environmental conditions in which these adaptions likely to be favored and preserved by natural selection and how commonly do they occur? Are there conversely environmental conditions in which intelligence/preintelligence might actually be disadvantageous and be selected against, and how likely are they to occur? And all of course, on a per planet basis.

    We can’t say anything intelligible about probability until we know the answers to these questions, and we can’t actually know without finding another intelligent technological civilization.

    Even finding primitive life elsewhere in our solar system won’t actually provide useful information for this probability assessment. Because if we do so, we might expect that many solar systems ought to have many worlds with conditions similar to places like Europa, Enceledas, Titan, and Mars, where life might arise but the habitability period of the world is too short, or the environments too marginal, to allow for the development of complex intelligent life, but we won’t be able to discern from that evidence alone, how likely a planet like earth (“like” earth in the sense that it is capable of producing and supporting an intelligent lifeform, rather than strictly similar to earth in environment/history/etc, as we don’t actually know how many different types of planetary environments/histories are actually capable of supporting the development of an intelligent lifeform) is, per solar system.

    The denominator issue just changes from N planets to N solar systems.

    Basically, no rigorous probability argument of any kind, for or against, can be made without finding at least one other technological civilization. Doesn’t mean we shouldn’t try to make such arguments, since the process generates useful information and questions, but we need to always be cognizant of the limitations inherent in the exercise.

  37. Daniel

    IMHO calling the Sun “Sol” is really nerdy… ;-))

  38. Nigel Depledge

    John Sandlin (29) said:

    It does seem likely that a species that develops technology will have an advantage over species that do not. So while not inevitable, technology is likely.

    This looks like a non-sequitur to me.

    Assuming techology in general gives a species as a whole an advantage, then whenever such technology arises, its use will spread through the population.

    However, this tells us nothing about how likely it is for a technological society to arise in the first place.

    For instance, tehcnology requires that the developers have big brains, and big brains come at a huge cost in energy, so a perfectly reasonable argument can be made against it being likely. Ultimately, we just don’t know. Our sample size is 1.

  39. Nigel Depledge

    Amphiox (36) said:

    So what is the sequence of preadaptions/mutations that lead to technological intelligence?

    Broadly, the following are necessary:
    Ability to plan;
    Ability to cooperate;
    Ability to communicate;
    Ability to manipulate;
    Ability to remember / learn.

    How many different ones are there (is the path that led to humans on earth the only way or not)?

    We have no idea. In fact, we may not have much of an idea about how to begin to answer that question.

    How likely are these events to occur?

    Independently, they are not all that unlikely – we see many examples in species on Earth (Chimps, dolphins, Caledonian crows etc.).

    Taken together, however, we have only one example so we can’t comment about likelihood or otherwise.

    What are the environmental conditions in which these adaptions likely to be favored and preserved by natural selection and how commonly do they occur?

    Don’t overlook the possibility that there may be multiple possible combinations that favour these kinds of adaptation.

    Are there conversely environmental conditions in which intelligence/preintelligence might actually be disadvantageous and be selected against, and how likely are they to occur?

    Well, the large brain comes at a large cost.

    If you take humanity’s other compromises and adaptations, we’re quite ill-suited to surviving when separated from our communities, so if a disease were to wipe out most of humanity then it might be difficult for the survivors to maintain our position as the dominant vertebrate on Earth.

    But that’s just speculation, really.

    And all of course, on a per planet basis.

    We can’t say anything intelligible about probability until we know the answers to these questions, and we can’t actually know without finding another intelligent technological civilization.

    Broadly, I agree.

    The development of intelligent, social apes able to manipulate tools and plan cooperatively is an historical accident on Earth, and we have little idea of how it came about.

  40. Nigel Depledge

    Amphiox (34) said:

    Slightly off topic here, and I’m not a chemist, but it occurs to me to wonder if, given that perchlorate is such a powerful oxidizer and so reactive, if it is abundant enough, could it be used as a source of fuel/energy

    IIUC, perchlorate is more stable than molecular oxygen, so is therefore a less useful oxidiser. It’ll also be heavier because of the chlorine.

  41. So does this go any way to solving the wider question of methane on Mars? I know very little about chemistry but could the methane be a product of the dichloromethane and chloromethane being produced on Mars?

  42. Nigel Depledge

    @ Christian Polson-Brown (42) –
    I don’t think it does.

    IIUC, chloromethane and DCM are products of chloride radicals reacting with hydrocarbons or other organic molecules. The chlorine – carbon bond is pretty strong, making for some quite stable compounds.

    By way of comparison, chlorocarbons and CFCs on Earth are very long-lasting (for all practical purposes, they are inert in the lab) until they reach the upper atmosphere, where they are photolysed by UV.

  43. @43: Nigel Depledge

    Awesome, thanks for the info.

    The whole methane on Marsh thing is IMO on of the most exciting questions in science at the moment. It would have been a let down if this was the answer…

  44. Brian Too

    @32. John Sandlin,

    I’ve long thought that the way to conquer this problem, is to create a fully automated, self-replicating probe. They would need some kind of system to share data (thus allowing information to propagate back and forth as they travel). You would also need a growth control mechanism to stop them from overwhelming galaxies and consuming all available resources.

    The idea is that you have inevitable losses as the probes travel. It doesn’t matter in totality however, because there’s a fleet of them and some level of losses are acceptable. They spread in a random fashion and thus some always return “home”. Every probe is built to have curiosity about every other probe, so if they are in proximity, they meet and share data.

    The real hard problem, I suspect, is that you might have probe evolution happening over long periods of time. They might divergently evolve and become unable to interface with each other. Also, they might start to require data storage, communications, fuel, or operational lifetime needs that far outstrip the original design. Ergo, probe evolution might be an operational necessity!

    It would take a visionary development project to create. The effort would take millions of years to even begin to pay off. However once you create the original batch of probes, they take the work from there on.

    I’ve got a feeling someone has written a sci-fi story along these lines already (Star Trek: TMP doesn’t really count as V’ger was a one-off).

  45. Zach

    @45 Brian Too

    Your probe idea has been explored by the series Lexx (http://en.wikipedia.org/wiki/Lexx)

    Unfortunately I cant remember the plot, but the growthrate of the probes got out of control and they did indeed attempt to consume all the resources in the galaxy. (citation needed)

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