A huge ocean may formerly have covered nearly one-third of the Martian surface two scientists from the University of Colorado at Boulder suggest.

In Nature Geoscience today, Gaetano di Achille and Bryan Hynek report how they analysed data that imply Mars was once covered by a huge ocean of water. Their evidence is a range of dry river deltas and valleys all at a similar elevation, meaning that the rivers fed into a single, great, body of water. This supports the idea that what are now the northern lowlands of Mars could have supported an ocean and therefore a water/atmosphere cycle much like Earth's.

Twenty years ago scientists scrutinising pictures of the Martian surface claimed to recognize extensive shorelines and networks of river valleys and outflow channels feeding in the same direction. Other scientists using thermal physics considered that such networks were likely carved by the workings of a complete water cycle, fuelled by an ocean of water.

So much water on Mars for many hundreds of millions of years may have helped originate, develop and sustain life forms, fossils of which could remain to be discovered by visiting space scientists. Where is the water now? How much remains on Mars? Might a useful fraction remain frozen in the subsoil?

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Martian dinosaur fossils would be awesome. Just thought I'd add that.
Life on Mars has not been proven one way or the other.
While even a microbe would be great, I was just imagining the many wonderful things we could yet stumble upon once we began poking around ancient shorelines, now that we think we know the elevation of some shorelines. Never mind how ridiculous it is to expect an actual dinosaur on Mars.
It evaporated because Mars has too weak a gravity to maintain a thick atmosphere. In the early days, it was likely volcanism that kept the planet warm enough to sustain oceans, alongside perhaps a strong axial tilt making the poles melt. If any liquid water remains, it is locked in subterranean layers and probably quite salty. Lackaday, the volcanism has all but ceased, and the planet’s surface is a now a cold, dusty desert.
Recent information supplied by the Galileo probe has revealed the possibility of a life form on Saturn's moon Titan - one based on an acetylene, hydrogen respiration (C2H2 + 2H2 --> 2CH4 + energy ). There is a real possibility that life existed or is extant on Mars and the Jupiter moon Europa with its liquid oceans, beneath its icy shell, could also harbor life.
If any or all of those sites show the presences of life it will be one of the profound discoveries in science. Further, they will have a life coding system that is RNA/DNA based or some other chemical energetics that codes the life form. Either possibility will astounding.
I heard about that last week I think, the atmosphere implicating that it was being organically processed. It's sad how many slack jawed dull stares I get when sharing that info with people I know.
The dull see nothing unique in the new.
That life appeared on this planet within 100 million years of the planet becoming suitable for it suggests to me that life is ubiquitous in the universe. Yes, I am a panspermist.

I suspect that the odd collection of circumstances that had to come together for life to begin from inorganic chemistry probably did not happen on this planet; it is my view that life began elsewhere and spread to this one via bacterial spores or the like, deeply embedded in meteors, protected from interstellar radiation.

Since we have recovered bacterial life from spores embedded in salt strata that are hundreds of millions of years old on this planet, it is hardly a stretch to presume that protokaryotic organisms could have hitched a ride on a meteor in such a stable form, and made it to our little rock. And every time our rock gets blasted with The Big One and large chunks of it get blasted into space, we are possibly sending out what we have received (even though it will probably take another unlikely event to eject them from our solar system.

Each required event in the chain is unlikely in the extreme. But if you give them enough opportunities, eventually they will happen, and we ourselves are clearly the result of improbability times opportunities.

So yes, I think we will eventually find fossils on Mars. Maybe even existing life, if the search is long enough and persistent enough. Then there is the problem of the methyl sulfate on Venus that shouldn't be there. And I predict we will discover life on Enceladus and Europa, when we finally get there, too. Maybe even hydrogen metabolizers on Titan. My prediction is that we will discover life wherever conditions are hospitable for it - and eventually in the atmospheric signatures of a few exoplanets as well.

The big question is why, if life is ubiquitous, we haven't been visited. There are lots of possible explanations, but that is outside the scope of this reply, and I won't delve into that here. But I believe that we will soon discover that we are not alone - and the idea that we are somehow unique will eventually become as quaint as the idea that the earth is the center of the universe.

Reading what you wrote earlier, it dawned upon me that there's only one species in the whole universe, and that humankind is only a stage of that species (we're what a chrysalis is to an insect.) We just need to evolve to a protokariotic stage, which will allow us to colonize other parts of the universe thru panspermia. We are the visitors.
Where are they? The most likely answer is that no advanced civilization, if they are out there, have overcome the light speed limit. And the chance of a generational ship finding use is remote in the extreme.
Having said that, I'm reasonable confident that life is ubiquitous throughout the universe – the bulk of it probably microorganisms or primitive forms.
There's the Fermi Paradox as well to consider. Far before ever attaining the level of technology sophisticated enough for interstellar travel, a species will unlock the ability to destroy itself. So if intelligent life is common, there is a probability that they are all either not advanced enough to say hello, or they are all dead.

The opportunity and ease to wipe out one's own species is so very much more accessible before ever making the many steps beyond it to become an interstellar civilization, that one could say it's fairly probable that any that do transcend the Fermi paradox, will thankfully for our sake, be benign in it's behavior. For any that are not benign will probably end up destroying themselves if they've hostile inclinations.

That doesn't save us from million tentacled hyper spatial cephalopods though with an appetite for dimensional consumption and domination. I still think Hawking is paranoid.

I lay awake nights agonizing over them - even worse, what if L. Ron Hubbard was right .......We're doomed.
I do, however, think your right; any civilization with advanced technology that doesn't exterminate themselves will likely be non aggressive.



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