I’ve been burned by NASA announcements before (remember “arsenic life”?), but this one sounds like it is genuinely important. There’s evidence of liquid water on the surface of Mars right now.
Liquid water runs down canyons and crater walls over the summer months on Mars, according to researchers who say the discovery raises the chances of being home to some form of life.
The trickles leave long, dark stains on the Martian terrain that can reach hundreds of metres downhill in the warmer months, before they dry up in the autumn as surface temperatures drop.
Images taken from the Mars orbit show cliffs, and the steep walls of valleys and craters, streaked with summertime flows that in the most active spots combine to form intricate fan-like patterns.
It’s nothing more than a thin, feeble trickle that appears seasonally, but the spectroscopic evidence says there are also salts in there. Hey, that’s enough! Life will find a way! I’d be willing to bet that there is some kind of single-celled life struggling along in these recurring slope lineae.
Send probes now! Mars has just become biologically interesting!
Wow, The Guardian actually had a science reporter who understood science!
It’s rare to see a story say what was known before, and what’s incremental piece is actually new. We’ve basically known for a decade that there is flowing water today on Mars (the MGS “nearly a decade ago” was preceded by other evidence IIRC). This study is just extra evidence.
Oh fuck, that looks goooooooooood!!
The fact that the trickles are stained seems to me to be particularly promising. Obviously not conclusive, but promising…
There must be a conspiracy theory in there somewhere.
Or something about ID.
Just liquid water on contemporary Mars?
Psh.
i thought they were going to announce something really cool, like this major coup by the Smithsonian Air & Space Museum, announced last april.
Just want to add that the first picture in the guardian article is so cool. I know it’s old technology at this point, but the fact that we can so accurately reconstruct what it would look like to stand there (and even virtually walk around) just based on overhead satellite images and geodesy blows me away.
Correct: it raises the chances. Before, our priors should’ve been that the chances were somewhere in the neighborhood of “super-duper-extremely-tiny.” Now they’re “very, very tiny.” Maybe that’s a big difference, but so what?
Not if there isn’t life there. Things which don’t exist don’t find ways.
Liquid water and salts (toss in a few more ingredients if you like) isn’t actually enough for abiogenesis, is it?
Seriously? You think the odds are better than 50% now, which is how you’d stand to win with this bet? Or do you mean that previously you might have guessed it was 0.000001%, but now that’s something more like 0.001% or even 1%?
I’d expect that if there were microbes on Mars, they might prefer to be wherever the water is coming from, rather than sliding out onto the dreaded surface, which is cold and dry and full of UV radiation that breaks apart organic molecules.
(I was at astronomy camp in high school when these things were first seen, and we watched the press conference as a group. I remember there was speculation if this was liquid water, ice or some non-water process.)
@consciousness razor;
We don’t know yet, do we?
I’d be willing to bet a dollar if the US treasury gave me one-trillion:1 odds. Hell, probably one-million:1 odds.
It’s all in the odds.
@consciousness razor,
But you don’t need abiogenesis to occur under current conditions, you just need previously generated life forms to have evolved along with the changing conditions. From what I understand Mars has changed drastically over the past 4.6by, so the relevant question re: abiogenesis is whether the conditions existed at some point in the past for life to arise (or, perhaps, if the conditions existed for life that arose elsewhere to survive).
Still seems like a longshot, but if life did arise on Mars, there’s at least a possibility that it’s still clinging on.
Well, we really don’t know how probable abiogenesis is, under any conditions. Its occurrence on earth might have been extremely unlikely, or darn near inevitable. So I honestly have no priors on this.
I doubt those criteria are sufficient. But you’re right that we don’t know. This is why you would be giving any odds in the first place: because we’re not so certain about some fact that offering the very high odds (that the sun exists, for instance) would just seem perverse.
The burden of proof should be on PZ for saying that it’s enough. But we don’t know that.
What’s the pay off supposed to be in the case at hand? Being excited or interested that life exists on another planet? That’s not a reason to believe that’s true, or a reason to be confident that you’re making a “good” bet that will be useful to you in the form of making predictions about future observations.
We’re talking about odds in the sense of a piece of evidence, which we didn’t know about before, raising (or lowering) the probability for believing a fact: that there’s life on Mars (or there’s not life on Mars). The new evidence is that there is liquid water, and I agree this evidence raises the odds. It doesn’t mean we should ignore what the actual odds are — after they’ve been raised by the evidence to some degree — when describing our knowledge, what is probably true, what we should probably believe, what we should predict, what this new evidence explains or doesn’t explain, etc.
If you use such things as a guide, to say that now the planet’s “biologically interesting,” so for instance we should invest in researching it, it doesn’t follow that because odds are better now (by some indeterminate amount) the pay-off is now good enough to justify such research. It may be that the odds are still too small to justify things like that. You’re moving in the right direction if the odds improve, but you’re not necessarily there yet at your destination.
We could probably build a lander with a drill that could go down a few meters on one of these things, to see if it hits subsurface water. Mars Insight is landing in 2016 with a drill that goes down 5 meters as part of experiments to determine the heat flow in Mars’ interior, and it’s doing it on a Discovery Program-level budget ($425 million plus the launch cost).
@Becca Stareyes
Same here. I’d be shocked if we found any surface evidence of life or organics, especially with those perchlorates being ubiquitous in the soil. We need to go deeper below the surface.
Now more than ever, it is imperative that terrestrial life not be allowed to go to Mars. Leave the investigation to antiseptic robots.
Even if it turns out there is some form of life on Mars, would that actually be evidence of abiogenesis? Or is it possible that any life from Mars could be hitchhikers from Earth? Maybe some sort of meteor impact kicked up some Earth bacteria into space, which were dormant before they eventually crashed onto Mars.
@consciousness razor, #11:
I wasn’t seriously talking about betting. It’s just that you said “50%” but lots and lots of betting happens where laying a bet doesn’t mean you think that something is 50% probable. And yet… without any odds mentioned (and there weren’t in the comment to which you responded) we commonly take a comment about “willing to bet” as if it means “p > 0.5”. So I threw in some whimsy, some fun, some, perhaps, flippancy.
Not flippancy targeted at you – just at the frustrating difficulty of responding to something as vague as “I would bet” and the frustrating tolerance for imprecision in a culture that sustains a phrase as vague as “I would bet”. Thus it’s meant to be targeted at me as much as you, since I share equally in that culture.
OTOH, if anyone has a spare trillion laying around and wants to offer one-trillion:1 odds to a single bettor of a single dollar, I’ll scare up the dollar lickety-speedo.
@futurechemist, #14:
Well, obviously at this point it’s possible that IF we find life that such life MIGHT be the result – in whole or in part – of life lifted off earth during an impact event, then carried to the surface of mars inside a meteorite*. Likewise it might be that any Mars-life might be descended only from living things that trace their ancestry back to an abiogenic event on Mars.
But that doesn’t mean figuring this out is hopeless: Mars-life may not employ DNA or RNA (though for all we know, it might be the only way life can reproduce with energetic and information efficiency, for all we know there might be many other ways as well…) or might employ different amino acids that are different from anything known on earth, etc. It would be very, very difficult to prove that those kinds of life never existed on earth at any point, but there’s probably a lot of work that can be done to make one hypothesis much more likely to be correct than another.
================
Would it be a meteorite? I mean, technically when a small rock is flying through space in a manner that is not regularly orbiting any local object (even if it does orbit the galactic core and/or even if it gets carried around something else that the galaxy as a whole orbits) it has become a meteor…and I’m told by reliable sources that a meteor doesn’t become a meteorite until it touches the earth.
Fine, you’re being flippant or whimsical, but to be accurate, PZ did say a bit more than that. I wasn’t only responding to “I’d be willing to bet.” Really, clarification would be enough for me, hence my annoying questions. It could easily be read as p>0.5, thus it’s now (but not before?) biologically interesting enough to send probes. Or it could be read a lot of different ways. Maybe there’s no real source of disagreement. That’s the sort of stuff my comment was intended to sort out, not to act as a rebuttal but because I do take his thoughtful perspective as a biologist and a scientist seriously (but not too seriously, especially if he’s not being thoughtful). Would he please say something a little clearer or more detailed about it — something along those lines.
My priors about Martian life were not previously so high that “liquid water exists on Mars” is enough to change my mind about it. It’s still not something I think is true, and I would not change my betting against it, in that sense.
I guess it’s a little more justification for sending probes to actually find it, if there is any, but not so much to make a real difference. I already thought Martian probes are fairly worthwhile to some extent (but certainly not a top research priority), even though I don’t think we’re likely to find any life with them. They’re worthwhile because, done properly, you could obviously learn a lot of interesting things about the planet in the process, even if you don’t end up finding life on it. That hasn’t changed for me either. Did it really change for PZ, or has not much changed? That seems like a reasonable question to ask.
More than arguably being interpretable that way as a specific mathematical statement, it’s easy to see it as an empirical prediction given the facts we now know, about what we’re likely to observe. So, you’d like to be doing at least a little better than chance, perhaps a lot better. If a psychic or a coin-flip can beat you at this game, it wouldn’t seem like your evidence is very good. Then, presumably, you wouldn’t be very comfortable concluding “now this is really interesting, so we should send a bunch of expensive probes to Mars!”
Crip Dyke, Right Reverend Feminist FuckToy of Death & Her Handmaiden @16
I’d go with that in an even easier way: it does not necessarily rely on lifting out ot an impact event. Fungi spores and bacteria are making their way out of the atmosphere at their own unfortune, but at least it is thought that spores can survive in outer space conditions. So while highly improbable to hit Mars from Earth, it is just a matter of time and number of unfortunate space migrants.
Lasting whenever you’re a lucky hit is another interesting question. Water and salts are not enough even with enough love. You would need sugar to sweeten your life or alcohol to forget about it. At the very end, maybe aldehydes for housekeeping. Even for fungi.
Cervantes @10
Sure, but it changes somewhat when there are organics. And organics seem abundant in space, or say may more abundant than thought at first.
I have a friend I disagree with in an amazing fashion: he thinks abiogenesis is highly improbable and then evolving intelligence is almost certain. I think abiogenesis is rather quite probable and certainly frequent, but evolving intelligence isn’t. Say for endless discussions… :-)
@CR
Sorry to step on your toes, CR. I didn’t quite realize that you were looking for more seriousness in this post & thread than I was, and my damn tone-of-type interpreter is on the fritz.
@Okidemia
I love having you and your knowledgeable, generous brain around these threads.
I really don’t know anything about surviving outer space, but you should know that I now have proof that seeds can survive airmail! This go-round seems to be more propitious than the last.
“Not if there isn’t life there. Things which don’t exist don’t find ways.”
Of course, by this reasoning life could not have arisen on Earth either. Presumably an unfortunate choice of phrasing.
Crip Dyke, Right Reverend Feminist FuckToy of Death & Her Handmaiden @21
Good! It’s not fruiting time now, we would have had to wait for another round. Not only seeds germinate, ideas too, but I’m writing as soon as I get out of dengue fever (well, maybe that’s just a bad flu).
Else spores surviving in space also made their way to cranky ideas, such as mushrooms being aliens trying to communicate with us, and Illuminati(on) fashions… :-)
Liquid water on Mars? Now expecting the next probe to be sent by Nestlé …
There may be some evidence of water on Mars but there is tons more evidence of wet blankets being present on FTB.
Crip Dyke… @ # 16: … when a small rock is flying through space in a manner that is not regularly orbiting any local object … it has become a meteor…and I’m told by reliable sources that a meteor doesn’t become a meteorite until it touches the earth.
Your reliable sources have it right, but they neglected to mention that before a space rock gains “meteor” status by entering the atmosphere it must content itself with mere meteoroid status.
Didn’t NASA already admit to blowing decon on one of the probes they sent to mars? So there’s probably a few earth critters up there anyhow.
@Pierce R Butler, #26:
Arrrrgggh.
You are correct, of course. Thank you.
Oh, and there was a New Yorker cartoon about the meteor/ite distinction that I’ve loved forever, but I can’t find online with a google search.
It’s just a simple line-drawing of a kid holding a rock (was it smoking? glowing? I can’t reliably remember…) but looking crestfallen when the adult in the room says:
You look again at the kid’s hands – maybe there’s a catcher’s mitt? Something to protect those hands? But no. Just hands. And you just start to laugh uncontrollably (or at least I did) as you think, “How the heck did this fiery-hot rock end up in this kid’s (unharmed!) hands without the rock ever hitting the ground?”
Anyway, I’ve remembered that part of the distinction ever since. If only there was a companion cartoon of little Billie in a pressure-suit with a gibbous earth rising in the background over the cratered landscape as the adult says, “Technically, Billie, it’s still a meteoroid until it touches the atmosphere…”
But that’s not funny, really. At least not in the bizarrely improbable sense of the first cartoon.
So I’ll just go on forever forgetting about the meteoroid/meteor distinction, as if I had no special education in astronomy and planetary sciences.
Sigh.
Knowledge is so cool. Why can’t I just be knowledgeable about everything, ever? Is that so much to ask?
@Marcus Ranum
The standards for the Viking Landers weren’t as tight back then as they are now IIRC, so if one of them ever cracks open it could kick some Earth spores into the Martian environment (personally, I don’t think they’d survive, and any Martian life would muscle them aside with ease).
There’s also Mariner 9, which is in a decaying orbit and will crash down upon Mars in 2022. If we’re lucky, it will burn up in the atmosphere and destroy any potential spores. If not, well . . .
The amount of dissolved salts must be quite high, to get the degree of freezing point lowering that seems to be occuring (although, in summer, at the equator, it can apparently reach at least 25 degrees C, no need for freezing point lowering for water to be liquid then.) But, earth has environments that are quite salty (I don’t know how they compare) in which bacteria live. I don’t know about abiogenesis in such high-salt conditions, the reaction chemistry would be very different, but I would think that something could happen.
Then, the salts they mention are perchlorates and chlorates, I don’t know in what percentages of the whole or what else may be present. Both of those, however, can spontaneously oxidize organic molecules, even explosively. Another barrier for abiogenesis to get around. But again, perhaps perchlorates and chlorates are not the majority of the salts present.
If perchlorates oxidize organic compounds, then that gives a metabolic pathway. The critters would need some way to eat!
Okidemia: a spore that floats out of the atmosphere and catches a solar-sail ride to Mars would enter the Martian atmosphere at high speed (multiple km per second) and just burn up, wouldn’t it? I’m moderately certain it would need a rock to hide in if it wanted to survive the trip.
I just thought of something weird. Any life that survives a space probe clean room is going to be some incredibly hardy stuff, selected for it by the pressures of humans doing their damnedest to kill it – meaning it’s worst kind of life to accidentally contaminate Mars with. So you wouldn’t you want your spacecraft to be contaminated with much more fragile microbes that displaces the hardy stuff back on Earth before you launch? The relatively fragile microbes will drop dead from the radiation and possibly the Martian environment on the surface.
Yes, perchlorates can oxidize organic compounds. The problem is that perchlorates are kinetically stable compared to the downstream (chlorate, chlorite, and hypochlorite) oxychlorine compounds, so that the control necessary for biological systems would be extremely difficult, if not impossible, to achieve.
numerobis @32
Outside my prediction ability… :)
I’m not sure about space kinetics, that’s beyond my skills. Certainly spores are not expelled from the atmosphere so they possibly are not travelling at high speed. (kinetics is conservative, right?). But then, I don’t even know about their longevity. Just the hypothesis of panspermia naturally occuring is plausible. We don’t know if it’s actually working. (yet?). Also, it might depend as to how spores are reaching the atmosphere: not every one will get frontward, we can think of some getting slowly caught after catching up orbitally. Just saying, I have no idea.
@consciousness razor
Why would you drag abiogenesis into this?
It’s much more likely that you’re going to find ancestors from organisms that were most successful many hundreds of millions of years ago when Mars was much more conducive to life.
Wherever the energy is coming from, they need escape velocity relative to Earth, if they’re not going to crash back into it. That’s around 11 km/s from the surface, slightly less from the upper atmosphere, and it would slow gradually as Earth keeps “pulling” on it.
This would be an obvious reason to think they’re probably not going to leave in the first place, so the whole plan should be scrapped. What made them accelerate so much, if they’re not firing rockets? But if they can escape at all, then there’s not much choice about what that entails. Any low-speed floating or drifting away from Earth will be counteracted by its gravity.
They would be pushed somewhat by the solar wind. Mars is farther from the Sun than we are, so that would be a positive contribution (don’t know, maybe not much), assuming they’re taking a relatively direct route. If their trajectory is toward the Sun, that would only make things worse.
To do it right, you need to know Mars’ motion at the time of arrival, which is constantly changing as it’s orbiting. If they snuck up “behind” Mars as it was moving away from them, that would lower the speed compared to the alternatives. But no matter what, even if they were somehow planted some distance away and started out stationary relative to Mars, it’s attracting them, so they’d accelerate toward it until they reach its terminal velocity, which is fairly high because the atmosphere is so thin. So, I guess burning up in the atmosphere would be less of a problem than you might think if you were assuming Earth-like conditions, but it’s still a problem. Having a nice big rock protecting you would help a bit, but that may not be enough either.
Because that’s necessary.
The most likely option is that we don’t find any organisms. And we can’t be very sure about how life-conducive it was. Indeed, we just now found liquid water. How much do you think we really know about what Mars was like hundreds of millions of years ago, and how much of it is highly speculative?
Even if it was a really friendly place for a reasonably long period of time, the chances seem pretty good to me that life still doesn’t emerge there. What else (if anything) does life need besides liquid water and salts? That was my question, and I sincerely do not know the answer. I doubt anybody does.
The possibility of life on Mars is very interesting, and liquid water makes it that much more possible.
So long as our probes and satellites don’t pick up evidence of huge cannon like structures, Cylinders or Tripods we’ll be fine…
Any life we find on Mars was either introduced there by contaminated probes in the last 40 years or it evolved. Mars is on the wrong side of the gravity well for matter to get there from Earth. We can just barely do it once every two years with the most powerful rockets we have.
We actually do know quite a bit about Mars’ past climate and geology, and there were probably a few hundred million years early on where it would not have been grossly hostile to life. Then it lost its planetary magnetic field, then most of its atmosphere. My guess is that any life that persists does so buried deep in the soil or the neutron flux would probably kill it.
I really want PZ to answer CR’s question. because I had the same reaction to the “i’d be willing to bet” statement.
@Consciousness_razor
The naked assertion here is that something relatively rare is involved besides flowing water, based on what if i may ask?
An energy source. Does the sun provide enough energy to allow life to form on Mars? Also, if it’s even vaguely earth-like life it needs carbon but that shouldn’t be a problem.
There’s an easier way to solve this issue than debating it though, or at least a more certain way: Send another probe with equipment to search for life. Any earth like DNA/protein based life will probably be due to probe contamination but if you find something that uses a different set of macromolecules that would be endlessly cool.