Ancient Mars was warm and wet, not cold and icy
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Thermodynamically expensive and wasteful when they could be usefully employed picking cotton.
When I read these articles I feel a bit sad that we will never know what was going on on Mars at that epoch. In C S Lewis's Out of the Silent Planet, an inhabited Mars is drying out and life there is drawing to a close as it is reduced to ever shrinking river valleys. The idea that something like that might actually have happened, but over 3 billion years ago, and that those billions of years more than physical distance separate us from what might have been our nearest living neighbours, does go some way to rub in how big the universe is in terms of our scale.
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ubercurmudgeon
Ars Tribunus Militum
How would you get them on board the rocket? Tell them that there is an enormous mutant star goat, and we need to raise their taxes by half a percent to pay for the hay to feed it?
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Well of course! Mars is a blood-red planet. As we all know, blood is hot and wet!
A cold and dry Mars would be more aligned with black bile.
Honestly, what are they teaching scientists these days?
Good to know that our future Martian colonists will have a source of fine china! May not have much call for paper sizing, though...
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The Noachian only lasted for a couple of hundred million years, and its seas would have been constantly disrupted by these enormous impacts. It doesn't look good for life! Yet the first signs of it on Earth are getting earlier and earlier as bio-marker signatures become easier to detect. Mars might actually be a better place to find the first signs of life, since it hasn't been completely reworked by plate tectonics and weathering the way the Earth has.
Somebody really has to get those samples back! SpaceX seems to be losing interest as the prospect of colonization recedes, and are now focusing on the Moon. I'm rooting for RocketLab's sample return efforts!
Somebody really has to get those samples back! SpaceX seems to be losing interest as the prospect of colonization recedes, and are now focusing on the Moon. I'm rooting for RocketLab's sample return efforts!
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Is that a river delta or an escarpment created by a lake that breached and suddenly drained? I didn't think that river deltas could create that type of feature.
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Just imagine that cellular life might began on Mars first and was delivered to Earth via martian rocks kicked of by meteorite impact. Heh, this way we would already be multi-planetary species 
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Deltas take different shapes depending on sediment load, depths and slopes. It doesn’t seem that different from birds foot deltas to me, for example this satellite image of the Mississippi Delta.
Edit to add
Rover images show clinoform geometry in cliff exposures, supporting the delta interpretion (Link to article in journal Science). Figure from article at scitechdaily.com. Looks like a load dominated Gilbert delta to me.
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The most recent work I’ve read puts the Last Universal Common Ancestor (LUCA) in the Hadean, over 4 Ga. If that is correct, life arose in similarly challenging circumstances on Earth, and survived the Late Heavy Bombardment. (Edited to correct spelling)
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Perhaps, instead of not understanding, you might look it up.
https://issnationallab.org/research-and-science/
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Whoa! It’s a giant step from a warm, wet environment, to a tropical one. Where did that come from at the end?
The problem is that every observation, which this study admits to, states that these wet periods were just thousands, to perhaps a few million years in length. Then they disappeared around 3.7 billion years ago. Really, that doesn’t give much time for life to appear.
The problem is that every observation, which this study admits to, states that these wet periods were just thousands, to perhaps a few million years in length. Then they disappeared around 3.7 billion years ago. Really, that doesn’t give much time for life to appear.
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Doesn't seem to have taken much time for life to appear on Earth, either.
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Even if Mars still had an atmosphere identical to Earth's you still wouldn't be able to live on the surface without shielding because Mars does not have a magnetic field. Colonizing Mars is a dumb idea unless you want to live under ground permanently, in which case it doesn't matter how cold it is or whether it has an atmosphere.
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One line of thinking is that the massive tsunami-scale tides of the early moon played a significant role in mixing minerals and whatnot into the oceans.
I don't think we fully understand the exact mix of critical ingredients behind Earth developing life, versus which ones were accidental.
Which is why it's such a profoundly interesting question whether Mars ever held life during its wet period.
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You're thinking about Venus. Venutians didn't take it seriously either.
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Early Earth also had a higher rotation rate, so a stronger internal dynamo and probably a stronger Coriolis force, affecting atmospheric storms and oceanic currents. Between that, external impacts, and volcanism/earthquakes, there was abundant energy available for mixing. I really don't see the Moon as a requirement for anything, although it certainly wasn't a hindrance. Right now, I'm not sure what conditions necessary for the origin of life that Earth might have possessed during the Hadean and that Mars would have lacked.
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Figures the new NASA crowd cancelled the return project. Afterall many of them believe humans magically appeared 5,000 years ago in that garden just like the earth is flat too.
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It is a delta with multiple avulsions, indicative of periods of higher than average flow. And at least one primary impact crater, indicative of a very bad day.
The shape is a classical bird's foot/fluvially-dominated delta, indicating that the rivers would carry the sediment to the edge of the lake and deposit it quickly. The sharp edges of the channels are probably due to that, though there may also have been some shaping by local currents. (There is also argument over whether this was a true bird's foot or a Gilbert delta with an extended apron of finer sediments). As Ceedave points out, it seems very similar to the Mississippi in style.
If you look carefully at the channels, you can even see the levees and some minor braiding.
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You have to zoom way in on the original image to see the diagnostic crossbedding, but is is so worth it. In addition, the poor sorting is suggestive of a very local origin for the rocks. I'm not as conviced about the Gilbert delta as the apron could have been formed later as end-noachian rains washed the fines out of the delta. It is worth noting that the apron is not entirely congruous with the channels.
Of course, shifting from bird's foot to Gilbert and back again is also a possibility as environmental conditions changed.
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When I hear about organic material that means they found oxygen, hydrogen, nitrogen and/or carbon. They are abundant on earth, and most of the rest of the solar system. But they don't mean "life".
There are a TON of factors here on Earth that make Earth a lot more unique than any planet or moon out there. I think the biggest among them is general stability in the environment over long periods of time. And by that I mean just the initial conditions. After the Theia/Earth impact that resulted in the moon, the Earth's rotation was stabilized so it mostly didn't precess as it rotated. It also had a LOT of water, and internal heat. And all of that led to a generally very long period of stability over most of the surface of the planet.
A billion years (give or take) later and that stability gave enough time for the chemical process that led to life to evolve into life and, eventually, over billions more years, to us.
Mars never had that stability long enough for life to form. Organic molecules may have formed, but they weren't the result of life. That just what the chemicals do when subjected to the environment they were in. Nor did they evolve into life. It just didn't have the necessary length of time in a mostly stable environment (among many other factors) for life to form at any level recognized as "life".
Something to remember about the search for life is that of all the life that ever existed on Earth, over 99% of it went extinct.
All because of comparatively MINOR environmental factors that made things hard on organic life in a world where organic life can actually thrive.
Or in simpler terms, you're never going cook a pot of stew if you keep throwing the pot against the wall. So, in the case of Mars, it likely had the pot thrown against the wall too often and didn't stay conducive to the formation of life long enough for it to have ever evolved. Organic chemical traces have to be complex enough to say, "this thing was alive once", and that's never happened so far. A small sample size for analysis is the only fly in the statistical conclusion ointment, but I'd be extremely surprised if life as we know it ever had a any reasonable chance of emerging on Mars, let alone sticking around long enough, and in enough abundance, to leave proof of is existence billions of years later.
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There are much cheaper and easier ways to remove people from society.
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We don’t have any knowledge on the effects of low gravity on humans, because we don’t have any data. Thanks to the ISS, we have an abundance of data on the effects of zero gravity on humans.
And thanks to all those years of ISS data, we have a good understanding of how zero gravity produces the various negative effects it has in the human body. And that gives some confidence that those negative effects will be far less in low gravity, if not eliminated entirely.
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This isn’t true. Mars certainly has higher radiation levels, but not so high that you couldn’t live on the surface before years with only minor health risks. NASA had a study around 2010 that predicted a 4% increase in lifetime cancer rates in a two year trip spent mostly in higher transit radiation levels.
Mars surface actually has radiation levels similar to some areas in Iran that have been populated for thousands of years without major health problems.
This is obviously simplifying a complex issue heavily. There are also cosmic rays that make it worse and habitat shielding can make it better, humans will wear heavy suits whenever outside, etc.
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You wouldn't be able to live on the surface of Mars because the average temperature is about the same as the coldest temperature at Oymyakon, generally claimed to be the coldest town on Earth. Typical cold spells in winter are around -110, 160K. Enjoy throwing your carbon dioxide snowballs, kids.
Consider how hazardous space walks are and extrapolate that to some sort of colony.
On the upside, wind chill factor is not very high. On the downside, the energy demands of keeping things adequately warm have to be met from somewhere. On Earth we didn't need to import fire, food, water or air in order to survive. On Mars, you have to start with adequate supplies in order to construct the means of getting more - and as we're currently struggling to get small payloads to the Moon, Musk's talking of Martian colonies in 20 years suggests he's been reading far too much pulp science fiction while high on ketamine.
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MilanKraft
Ars Tribunus Angusticlavius
"Yes," "yep," and "I am inclined to agree," based on what I've read.
In light of the recent self-replicating RNA article at Ars, it's certainly possible the precursors of complex life could've evolved on Mars. Or at a minimum, we should be optimistic enough to continue looking as our understanding of biogenisis improves. But anything beyond simple multi-cellular life on Mars seems unlikely, barring some unforseen major discovery later. And who knows how much later, given our current "space culture" and the people driving same.
Would love to believe we will return to a "more planetary rovers, more probes and research satellites, and more space telescopes" mode of operation vs. "Moonbase Grok at Trump Crater, sponsored by BlueChew-Origin and Pfizer Lunar-ceuticals, with a final word from Google Moonrocks space candy (we know they love portfolio diversification)"...... but I ain't holdin' my breath.
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Much of the water seems to be still there, just deep underground. Much harder to reach for us, but (simple) life could still be extant down there.
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Statistical
Ars Legatus Legionis
Earth atmosphere has more of an impact in reducing radiation on the surface than the magnetic field. Hell even the tiny atmosphere that Mars has today has a significant effect compared to deep space or the moon.
A magnetic field is a nice to have. It isn't essential for life either complex or single cellular.
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Tell them is tax free, no capital gains, and no gov regulations and that they can monetize anything they want while there and no one will stop or prevent them from doing anything they want with their money or land.
Then we just don't send anyone BUT them.
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