Mars lost all of its (surface) water presumably due to solar wind, and thus never had time to evolve complex life. Earth would have faced the same fate were it not for the fact that the Moon collided with us at some distant point in time, surrendering its iron core to ours. Now, our Rare Earth has an unnaturally large active iron core, resulting in an unnaturally efficient magnetic field which is able to protect our waters from being blown away by Sun.
Just wondering, what would have stopped the Earth from having enough iron on its own in the first place? If the Moon could have that much iron, the Earth could as well have had it without needing to mix with the Moon, they're made from the same original matter after all.
The OP mispoke. It wasn't the moon that collided with earth, but another planet around mar's size. As a result of the collision the the core of that planet combined with the earth and the crust and parts of the mantle were ejected and coalesced into the moon.
I think the point still stands though, right? The moon is only 1% the mass of the Earth so if we had all that extra crust it wouldn't make our crust to core ratio so off that we couldn't have an atmosphere.
Read TSiege's correction again, it wasn't a (bad numbers) 1000T planet being impacted by a 10T object, it was a 500T object (earth) being impacted by a 500T object (now also earth) and ejecting a 10T object (now moon) from the debris.
Without the event we'd have a planet even smaller than mars!
I guess the question is rather than having 2 planets of 500T each form then collide, couldn't a single 1000T planet have formed from the same material?
I think the answer is yes, but the only way you get the dynamo of our core(thus strong magnetic field) is that collision, but that's just my fuzzy understanding from occasional reading over the years.
According to the article below, the impact may have started the magnetic field by mixing the core. It doesn't mention anything about "adding more iron" being in itself more significant. I wonder if the OP is half-remembering a distorted version of this theory.
One might be inclined to attribute the amount of good luck to devine intervention, but to this I would say: If the conditions on our planet would not have allowed for higher life, nobody would have been there to ask themselves why the conditions were slightly off.
It's not that the water "blew away" in the solar wind, it's that the atmosphere did, taking the water vapor in the atmosphere with it. This is a very gradual process, which would happen on Earth too, if not for the magnetic field.
I don't know that the collision with the moon is the secret here or not. I think it's complex.
Mercury has no magnetic field, and no meaningful atmosphere like we'd understand it. Venus has a minimal magnetic field, and is covered in hot dense CO2 layer because the solar wind blew away all the hydrogen and continues to blow away the atmosphere. The Earth has a much stronger magnetic field that has protected our oxidized hydrogen, and good evidence points to the giant impact hypothesis.
I have very little reason to believe life evolved in Earth or even in Mars for that matter. The more likely scenario is that there’s rocks floating around everywhere that have spores of life throughout the galaxy ready to seed a suitable planet in geologically instantaneous timelines. That will explain the extremely rapid emergence of life on earth initially while it took a few billion years to evolve any further. In which case if Mars had flowing water at some point it likely also harbored at least single cell life.
Source: biologist but not specializing in evolution.
But you only introduce an unnecessary extra step in the same theory. Life still had to evolve somewhere, just that now it had to embark onto interstellar trip.
But instead of having a single planet generating random molecular combinations to roll for proto-DNA, you have billions or more. Life would have to evolve extremely commonly for it to be more probable to evolve by itself on any specific planet than on literally any planet which then encouters an event causing panspermia.
But alas, that's an external observer viewpoint. It's important to note that it does not say that life is more probable to have evolved somewhere else than Earth (since we have an effective sample size of 1). It only says that the extra step introduced in the panspermia theory does not have a negative probabilistic impact, on the contrary.
It's a big question as to why life started on Earth as soon as it did, pretty much as soon as it was even possible.
That could be because life is very easy to start if conditions are right. In which case it's quite likely to have started on early Mars too, and we should expect to find at least simple life all over the place.
The other possibility is that it didn't start on Earth, and was seeded from somewhere else.
The big question is how local regions of low entropy that exhibit metabolism and replication (ie. life) came into existance out of inanimate matter. Where it happened is secondary.
Why not add more steps? The aliens¹ brought microbial life on an interstellar ship and seeded it. A lot better chance than riding out for a few million years on a piece of rock! See, it's approximately on the same trailing end of unlikely as panspermia, but I fancy this one more.
1. How exactly are these spores of life getting into asteroids and being pinged around the Universe? The mechanism seems absurd to me. Earth is teeming with life, but outside of our explorations I believe none of it escapes our planet at all.
2. The life that would reach us would be already specialised for whatever environment it came from, and I would imagine would result a lower amout of variety, since it's already a successful species. But on our planet we have a massive amount of variety, which I believe points more to a bootstrapped start where competition was less intense, and odd things could develop, which were later outcompeted (see the Cambrian explosion).
Disclaimer: Not even a biologist, but I'm more willing to accept that life started and evolved here. Of course that might all be cast in doubt if we detect masses of life on asteriods or metoerites, but the first attempt at that seems to have come up with nothing so far.
Collisions? Large enough collisions eject large amounts of rocks into space. A good fraction of rocks ejected from earth would have some viable single cell life inside it, all you need are some cavities in them that don’t reach insane temperatures during this process, which is very possible for big enough rocks.
Remember that while you deal with insane numbers on the space side, viz. it’s emptiness, the number of planets etc., you’re meeting an insane adversary with biology as well. The number of cells in a single piece of sand in this planet is insane. The number of particles we might eject if there’s a catastrophic event from earth is insane. Anyone who worked on biology would know how hard it is to keep things truly sterile. I’m just extending it to outside space as well.
As for the conditions being too specific, while it’s true, I don’t see many outrageous combinations you can commonly observe in planets in the galaxy so I’m not sure if that’s a big deal breaker.
NASA proved in the 70s that some microorganisms survive atmospheric rentry. In fact, they could not possibly be killed by any means known to man, except for some enormous cosmic event with very powerful radiation / cosmic rays. This was done to question the idea of it being "safe" or not to travel in space or other planets, if it is possible to "scrub" our ships clean and avoid bringing germs with us. Apparently thats not 100% possible, some critters survive space and the harshness of re-entry just fine.
What makes you think panspermia is more likely than abiogenesis?
The only data point we have suggests the evolution of eukaryotic cells and multicellular life is simply less likely than abiogenesis. There are plenty of hypothesis to explain why that might be the case.
Rovers are not the most effective tool for searching for fossils, especially microscopic fossils that can’t be seen from a distance on camera. They’re just the most effective tool we can send at the time we sent them. But a rover is only slightly more effective than just sending a dude with a buggy and a child’s beach kit.
Many, many single-purpose rovers can be sent in the place of a human mission with no risk to human life. There is no scientific justification for sending humans on a science mission, it's mostly just adventurism.
I think I'd feel better about the suggestion for a manned mission if it talked about 1) what value a human would offer in collecting samples and analyzing data over a robot 2) how that value would compare to mass of air, water, and food as well as life-support systems and radiation shielding; the additional fuel and oxidizer to move the mass of the crew and supporting systems 3) the ethics of sending someone capable of doing this important research to their probable deaths rather than an unmanned mission and 4) the cost-benefit to funding this versus other non-space exploration efforts.
What also gets to me is that clearly people have done this cost-benefit analysis before - people that know a lot more about the topic than me. It lacks humility to ignore their reasoning (see https://spacenews.com/independent-report-concludes-2033-huma...).
Highly doubt this, but I am no expert. A human is just very flexible and the rovers up there look super complicated while only been capable of very simple tasks. A lot of scientific progress happened because somebody took a risk, not in the name of adventurism, but in the name of science.
Interesting. Indeed the wording is not great but a human would get the idea :-) I did notice that quite a few times when i write that i want space exploration and expansion it gets downvoted. So there may also be a crowd that thinks we should solve all problems on earth before going to space, as if thats possible or achievable.
A batch of those people roll through every space related post and downvote things, but then the tide shifts later in the day. I'm pretty sure the vast majority of the users here are strongly in favor of getting humanity into space
> I'm pretty sure the vast majority of the users here are strongly in favor of getting humanity into space
How do we turn this into a meaningful political movement? My strongest pro argument in a political context is resource security and not having to rely on adversarial states. Economically, it means and endless supply of sources we need to build our increasingly complex devices. Also jobs. I see this as an existential benefit for advanced societies. But how do you bring this is front of average joes with the same intensity as current issues.
> These days, there seems to be nowhere left to explore. Victims of their very success, the explorers now, pretty much, stay home. Maybe it's a little early- maybe the time is not quite yet- but those other worlds, promising untold opportunities, beckon. Just now, there a great many matters that are pressing in on us that compete for the money it takes to send people to other worlds. Should we solve those problems first, or are they a reason for going? Our planet and our solar system are surrounded by a New World ocean: the depths of space. It is no more impassable than the last. - Carl Sagan
Man, that's an interesting idea.. I just figured the financial prospects of being first to access unlimited wealth would be plenty of motivation to get us to space
I feel like space investments are a lot more valuable than most of the stuff politicians care about nowadays, though, so I'd be interested to support a movement like that
If the most compelling recent hyopthetical solution to the Fermi Paradox is correct [0], finding anything other than a totally sterile Mars would be very, very bad news for humankind.
> The water which supplies the farms of Mars is collected in immense underground reservoirs at either pole from the melting ice caps, and pumped through long conduits to the various populated centers. Along either side of these conduits, and extending their entire length, lie the cultivated districts. These are divided into tracts of about the same size, each tract being under the supervision of one or more government officers.
> Instead of flooding the surface of the fields, and thus wasting immense quantities of water by evaporation, the precious liquid is carried underground through a vast network of small pipes directly to the roots of the vegetation. The crops upon Mars are always uniform, for there are no droughts, no rains, no high winds, and no insects, or destroying birds.
> The crops upon Mars are always uniform, for there are no droughts, no
> rains, no high winds, and no insects, or destroying birds.
Presumably the are still seasons, cloud or dust storms, and wind. Possibly also variations in supplied nutrition and water pressure, maybe even water impurities and minerals. Radiation fluctuations might lead to crop variance as well.
We live in truly amazing times. In a few years NASA may succeed in sending probes from Mars to Earth and we may get evidence for past or current life on Mars.
In 10 or 15 years if Starship works out we may be able to send scientists to Mars.
I'm a fan of the hypothesis that life on Earth came from Mars - will be very interesting to see how it develops as we study Mars.
Mars is smaller and cooled down before Earth. That means it had liquid water while the Earth was still too hot. Therefore, it's possible that life first appeared on Mars, and was later transferred to Earth on a meteorite.
Interesting. How would a meteorite pick something up in one planet to carry it to another planet? I'm presuming that the hypothetical meteorite does not originate in Mars.
A big enough meteorite impacts Mars hard enough to blow up bits of the latter beyond escape velocity, those bits then float in space for a long while then some may end up being captured in Earth's gravity well all the while evading Moon's one, and if big enough maybe becoming meteorites themselves over here.
It's kind of a mind boggingly huge billiard game.
With a bit of luck, life was somewhere around the initial impact, a couple bits of life survive blast energy, cold of space, radiation exposure, passage of time, atmosphere entry, and impact, and finally feel cozy enough on the new rock to replicate.
Now, the metagame is to assign numbers to all of that, and compare that to the odds of molecules assembling themselves into spawning life locally by itself. Also the latter must have happened somewhere first anyway, the question mostly being which of it is it for Earth.
This seems incredibly far fetched but the time scales are galactic, and so it kind of looks like it happened a few times over but we're not quite sure yet:
It’s beyond obvious that water flew as rivers in Mars at some point, and looks like there’s some water there even now!
Even life, is there any reason to think there WASNT some microscopic life there at some point? I doubt anyone thinks there’s viable life there even now (though one can’t 100% exclude the possibility).
It’s like everyone kind of already knows these are the likely facts but we keep using these as scapegoat questions to fund more missions for rovers etc. Instead, wouldn’t it be better if we are honest to oursleves and find things we actually want to do? Like get some people there? Which again, more than the science is just about the accomplishment itself.
I’m genuinely curious about places like Europa. I’m not at all curious about digging more Martian dirt and doing increasingly insignificant geology on a dead planet.
I would argue that the main thing holding us back is the lack of funding. NASA's entire budget can't even compete with Meta's R&D department, so they have to take small steps. Investigate Mars, try to get people back on the moon (Artemis), and go from there.
Eventually we'll get to a point where we can explore Europa properly and we can send people to Mars, and all that, but it's going to take time. Without enough funding, things just take a lot of time.
You have it backwards. NASA is actually really good at exploring other stuff in our solar system. They have sent probes to all kinds of places, recently direct imaging Pluto with New Horizons.
Their budget is actually absurdly large. The problem is they are mandated to engage in vanity projects like Artemis, which don't do anything to contribute to science at all.
>Even life, is there any reason to think there WASNT some microscopic life there at some point?
We have no clue about how likely it is for life to emerge or how it happens, so we can't really tell. Maybe we're on the only planet with life in the universe.
Finding proof of life on Mars would completely change that equation.
Science is the difference between "everyone kind of already knows" and proven facts. Don't confuse a hundred years of Martian sci-fi with actual scientific discoveries about Mars.
Not being snarky but that is what Science is supposed to be. Unfortunately, it has mutated to the more warm & fuzzy "everyone kind of knows." Case in point, it should be "trust the data" but instead we get "trust the experts." The irony? We all know expertise in humans is fleeting.
So agree, but the logistical challenges for even landing a probe on somewhere like Europa or Enceladus are far greater than landing somewhere as inert as Mars. Jupiter has an incredible magnetic field, we'd need to somehow land on the moon (which is a challenge in itself due to the potential for 30m spires of ice), drill through the surface ice and possibly through multiple subsurface oceans til we reached a layer that had geothermal vents.
Also while I agree with you that it's very likely that there was microscopic life on Mars at some point in the past, considering that finding evidence of life on other planets would be one of, if not the largest discovery in human history, I think it's important to keep going until we confirm it.
>There has long been debate in the scientific community about whether Mars had an ocean in its low-elevation northern hemisphere, Cardenas explained. Using topography data, the research team was able to show definitive evidence of a roughly 3.5-billion-year-old shoreline with substantial sedimentary accumulation, at least 900 meters thick, that covered hundreds of thousands of square kilometers.
I feel like the announcement that bodies of water have been found on Mars has been made every few years since the late 19th century. You'll have to drill into the details to learn what they actually found.
