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Water On Mars

Rust never sleeps...on Mars

Another article about whether there were ever oceans on Mars, the colour may be meteor dust, not rust.

Ties in with Rynner's post about the missing carbonates.

Full New Scientist article at:

http://www.newscientist.com/news/news.jsp?id=ns99994120

Red planet's hue due to meteors, not water

18:28 04 September 03


Why is Mars red? The generally accepted explanation that liquid water rusted its rocks may be wrong. Lab experiments that mimic the environment on Mars suggest that the planet's reddish hue came from a dusting of tiny meteors falling on the surface. The result is fuelling the debate about whether Mars was ever hospitable to life.

The mineral that gives the planet its colour is a reddish iron oxide. Until now, astronomers thought that it probably formed in a chain of chemical reactions as iron in rocks dissolved into pools and rivers on the warm young planet. The iron oxidised, precipitated, and was then blown all over the planet.

But Albert Yen of NASA's Jet Propulsion Laboratory in Pasadena, California, began to doubt this after the Mars Pathfinder mission reached the Red Planet in 1997. The mission revealed that there is more iron and magnesium in Martian topsoil than within its rocks. This suggests the minerals actually came from the small, metal-rich meteors and dust particles that constantly fall onto Mars, says Yen. Calculations suggest they deposit five centimetres of surface layer every billion years.

If that is the case, Mars might not have been so wet after all. To test whether this topsoil would have needed water to oxidise and turn red, Yen exposed metallic iron to ultraviolet light, simulating sunlight, in a chamber containing gases similar to the Martian atmosphere at temperatures as low as -60 °C.

Red iron oxides started to form within a week. No water was necessary, Yen told this week's meeting of the American Astronomical Society's planetary science division in Monterey, California....

Yen does not claim water never flowed on Mars - the planet's networks of dry valleys and channels are good evidence that it did, he says. But flowing water seems to have played only a small role in weathering the surface.....
 
Ice ice baby!!!

Europe probe detects Mars water ice

Friday, January 23, 2004 Posted: 1421 GMT (10:21 PM HKT)



(CNN) -- The European orbiter Mars Express detected ice at the Red Planet's south pole, mission officials at Darmstadt, Germany, said Friday.

NASA's Mars Odyssey, also an orbiter, confirmed water ice at the north pole, along with dry ice -- frozen carbon dioxide -- in 2002. It picked up signs of hydrogen at the south pole, the first indication that water ice might be found there.

Mars Express confirmed Odyssey's suspicions about the south pole.

"We have already identified water vapor in the atmosphere," scientist Vittorio Formisano said. "We have identified water ice on the soil on the south polar caps."

Mars Express headed off for the fourth planet on June 2 specifically to look for water. It carried with it the European Space Agency's rover, Beagle 2, but that craft was never heard from after its expected Dec. 25 landing.

Express, however, attained its final operational orbit in the last week and has continued its scientific mission. Express made an unsuccessful attempt to contact Beagle 2 earlier this month when it passed near the rover's landing site

http://edition.cnn.com/2004/TECH/space/01/23/mars.water.ice/
 
evidence of water "unequivocally" shown

http://news.bbc.co.uk/1/hi/sci/tech/3524275.stm

Mars rocks once 'water drenched'


The rocks are being studied intensively by Opportunity
Nasa says its Mars rover Opportunity has shown unequivocally that the Red Planet had the right conditions to support life some time in its history.
The rover has revealed the rocks at its landing site were once in contact with substantial amounts of liquid water.

"These rocks were modified in liquid water and may have been precipitated in water," said scientist Steve Squyres.

Opportunity has been studying the local geology at a location called Meridiani Planum since its landing on 25 January.

Professor Squyres, the principal investigator on the rover's science payload, said his team had been engaged in a fine analysis of a section layered bedrock at the landing site.

"For the last two weeks we've been attacking it with every piece of our hardware and the puzzle pieces have been falling into place," he told a special news conference at the US space agency's headquarters in Washington DC.

"Were these rocks acted upon, were they altered by liquid water? The answer to that question is, definitively, yes."

Rich in sulphur

He said there were several key lines of evidence to support the conclusion.

These included the rocks' physical appearance. Their cross-bedding, the presence of small spherules and indentations all pointed to water modification.

The rover's instruments also detected high levels of sulphate salts which on Earth would normally form in water or, after formation, be highly altered by long exposures to water.


Nasa has two rovers on opposite sides of Mars
"The only way you can form such large concentrations of salt is dissolve it in water and allow the water to evaporate," said mission scientist Dr Benton Clark.

In particular, the rover found jarosite, an iron sulphate mineral which suggests an acid-rich lake or hot-spring environment might have existed at Meridiani Planum.

"The purpose of this mission was to go to Mars and see if it had habitable environments," said Professor Squyres.

"We believe at this place on Mars for some period in time... this was a ground water environment that would have been suitable for life. That doesn't mean that life was there. We don't know that."

Rock return

The scientists still have to show the rocks were originally laid down by minerals precipitating out of solution at the bottom of a salty lake or sea - that they were formed like the water-derived sedimentary rocks found on Earth.

Nasa's scientists said it was not possible to say when the wet environment at Meridiani Planum existed.


Nasa believes the spherical granules have a watery origin
Neither the Opportunity rover, nor its twin, Spirit, is equipped to date rocks.

"The best way to get at the age is going to be to bring some of this stuff back," said Professor Squyres.

And Nasa officials believe a sample return mission should now be a priority.

"One of the pathways of exploration... is to undertake perhaps the most challenging robotic science mission we could imagine to another world - and that is to return pieces of Mars to Earth," said Dr Jim Garvin, the lead scientist for Mars and the Moon at the space agency's headquarters.

"These first results are a good compass point that says 'we know a good place go and get Mars, figure it out on site like we're doing and bring it home to all those [Earth] labs'."

He said a future mission could involve a rover that scoured the surface for interesting rocks which it then took back to a mothership for despatch to Earth.

Opportunity and Spirit are controlled by a team of scientists and engineers working out of the Jet Propulsion Laboratory in Pasadena, California.

Spirit touched down in Gusev Crater on the far side of Mars to Opportunity on 4 January. It is investigating an area which scientists think may once have held a lake.
 
some comments on NASA's announcement about water on Mars

To all:

The announcement, by NASA, that it seemed Mars once held oceans of water will, likely, be a matter of great attention, for many. However, the approach to the entire "Mars water" situation demonstrates some unpleasant, even denigrating, facets of what is being called the "scientific method", these days.

The way the entire matter has been addressed is to assemble information that is considered interpretable as that Mars once held water. To be sure, the means used can yield information. However, an important provision in “traditional science” is that everything be viewed “within a context”, that is, as part of a larger universe, both spatially and temporally. Those interested in the question of water on Mars, however, seem to have hitched their star only to whether any evidence of liquid water, in the past, could be found. No other aspect of the situation is discussed, anywhere. Indeed, it is pretended that there are no other points to be addressed!

But, in fact, there are many significant points contingent on the discovery that water once flowed freely on Mars.

Among the most important, where did this water go? To raise the issue of Mars once having water is to automatically invoke the idea of its having left. And that brings up the matter of where it left to! What would be considered an authentic version of “traditional science”, not the glitz-ridden ersatz that seems to be filling the periodicals, these days, would have done! The idea of Mars once having water wouldn’t be complete without such considerations as where it went! Those questions are embarrassingly conspicuous by their absence!

Those disinterested in anything even approaching the more legitimate form of “traditional science” would simply brush this off with a cursory and diffident: “It evaporated.” In fact, this seems to have been mentioned in some articles. But that still leaves the issue that, once water evaporates, it doesn’t disappear! It goes somewhere else! That’s demonstrated in the cycle of weather on earth! But there seems no sign of the water that once was supposed to have formed oceans on Mars!

Pushed to it, some may hazard such suggestions as that it left the planet’s atmosphere.

Actually, in the face of the lack of any water visible now on the planet, that would seem a theory they would be forced to!

But that raises even more important questions. However, if the question of where the water went may seem an unlikely point for those obsessed with only the most immediate to notice, much less approach, the follow-up points to the issue of the fate of Mars’ water seem utterly beyond the possibility of quick address by them.

Because the idea of missing oceans on Mars raise genuinely thorny issues about the concepts defining the development of planets!

Among other things, at least according to standard theory, Mars wasn’t just plopped into place at time 0, and permitted to develop from then on. What is seen happening now can be described as an aspect of what has dominated Mars throughout its history.

Those who concentrate only on the victory of having discovered that liquid water once flowed on Mars, forced to an answer of where the water went, likely will suggest that it escaped into space. They will, apparently, reliably invoke Mars’s lesser mass and, therefore, smaller gravity. Even in the colder area of the solar system where Mars now sits, they could assert, the planet’s gravity will have been too small to maintain any water for very long, especially considering the extremely low atmospheric pressure. Water, they will declare, would readily boil away into space, over long enough periods of time. And, measures up to 4 billion years, as the time since the oceans supposedly covered Mars, are, evidently, being bandied about.

This raises the question, though, of how Mars could ever have had oceans!

If it’s too small to have held water, how could it have maintained enough water to form oceans? In conventional theory, as Mars formed, and was, supposedly, bombarded by comets, carrying water to its surface, it was smaller and hotter than it is today! Not only will it not have as much, or as little, gravity as it has today, any water on its surface would have been far hotter, and, therefore, more likely to escape to space, than water in later ages! And it almost certainly didn’t have enough atmosphere to hold water in the liquid state, either! What is more, any water delivered by comets will have been provided, likely, in small amounts, relatively speaking, over extended periods of time, so there would have been no sudden influx, either, of water, onto the planet!

Whole swaths of conventional theory are utterly at odds, evidently, with the idea of liquid water in bulk ever having been on Mars’ surface!

Of course, you could suggest an alternative that could involve water in bulk having existed on the planet’s surface. But it will, essentially, require the equivalent of “starting Mars at time 0”. If, it can be suggested, some alien race landed on Mars, finding it the closest to their natural surroundings - even including planet earth - they may have set about “planet-forming” Mars, by a massive, but quick, bombardment with comets, to bring water to the planet’s surface! Once they left, for whatever reason, they may have left Mars to its own devices, which set the evidently inexorable process of water loss into operation.

Being an introduction of water in a manner not consistent with standard planetary development methods, and the time of its introduction being after Mars had cooled, this would have a greater likelihood of forming at least a temporary ocean there! In fact, if the past existence of oceans is proved, this theory may be the only one, in at least modest agreement with “traditional science”, that can be applied to explain it! The assertion that water once flowed on Mars may, in fact, legislate for the existence of other life in the universe! And you don’t need to see the aliens to “establish” that they were there; you only need the footprints of a being to know that it passed that way!

An ancillary point can, perhaps, be introduced, here.

A commonality for those who push for life having once been on Mars are orbital photographs of eminently enigmatic structures on the planet’s surface. The Cydonia “face” is, apparently, only a sample! Many are represented as “pyramids”, “cities” and “traveling tubes”. To pursue this appropriately, however, a degree of understanding of the appearance of structures from orbit can be useful. There are a number of sites that, apparently, provide photographs from orbit of places on earth. Pictures of the pyramids, for example, can be easily obtained. Comparing them with photographs of the surface of Mars can be said to be unavailing. The pyramids on earth are quite sharp and geometrically correct. The structures on Mars, however, do not necessarily seem to show any geometric precision. It can be suggested that they were on Mars for very long, that the winds of the planet may have sand-blasted them, and that they may, largely, be buried by sand and dust. To be sure, the pyramids are only about 4,000 years old, and, if suggestions are correct, life may have persisted there only until about 4,000,000,000 years ago! Any structures built then could have suffered greatly by exposure to the atmosphere, in that time.

However, another point may be derived by looking further on the Giza plateau, beyond the pyramids. Situated, there, too, is the Sphinx. That massive structure is far from overly geometrically precise. Without extreme exactness, it can almost be interpreted as a non-geometric formation. If there are no signs of precision in the enigmatic structures on Mars, they may all be sculptures of sorts!



Julian Penrod
 
Where did the water go?
Where do you think Noah's flood came from? :devil:
 
Well, first step was to find out if there had been water. Now we can start trying to find out where it went.
 
You're forgetting that when Mars had water, it probably had a thicker atmosphere as well and lost both, simultaneously, over millions of years - BTW it's possible to have an atomosphere consisting mainly of water vapour - we're talking geological time scales not boiling off water like steam from a kettle.

Furthermore, we don't know if all the water is gone, some is probably locked up in the polar caps, much could be in a permafrost layer deep under the surface - that's for another mission to find out.

As to where there water came from, some probably came from later cometary bombardment, a lot would have been there when the planet originally accreted (if you accept current ideas off planetary formation) from a halo of dust and ice in around the sun. Billions of tonnes was probably boiled of before the planet cooled, billions of tonnes could have remained.

Again we're talking deep time and scales beyond our everday experience.

IMO the things on Mars are weird-looking natural formations. People tend to forget that although Mars is smaller than earth, because so much of the Earth's surface is covered with water, the visible surface of the Earth is about the same as the visible surface of Mars. Also a lot of the Earth's surface is covered by vegetation and to a smaller extent artefacts: with Mars you've got naked geology, so the chances of seeing unsual features are higher.

Also, I can't imagine any artifical structure being recognizable as such over a 4 billion year time scale, even with much slower erosive and geological processes they'd have be ground away. I suppose something might endure on the Moon if there were no major meteorite impacts on the site, but on not on Mars where even now there's weather.

If those things are structures, they were built and abandoned a lot more recently.
 
As Mars cooled down, volcanic activity died away. With no volcanic activity, the water that was left was not replenished at a fast enough rate to keep up with loss of vapour into space.

Earth is different to Mars - it's closer to the Sun, and hence warmer, and has a particularly large moon that causes tidal effects. Hence, this planet still has volcanic activity, and lots of water. I'm pretty sure there was a thicker atmosphere and lots more water on Earth at some point in the past, but a lot of it has boiled away into space.
 
planetary science

venus lost its water because it was too hot.
mars lost its water because it was too light (low gravity)
earth is the third bowl of porridge.

J. Penrod's critique is rather specious. The whole thing is explained in my planetary science textbook. i can dig it out if you like?
 
Re: planetary science

sninik said:
...J. Penrod's critique is rather specious....

Agree with you there. Does seems to be a bit of an element of creating a mystery of something that's adequately explained (possibly not right in all details, but we live and learn).

I think there's a set-up for an Ares-forming theory going on.
 
Water loss from Mars

It certainly seems likely that Mars had a lot of water at some point; if I may, I would like to give a little prehistory of Mars, given the evidence available before the Spirit and Opportunity landings. Any or all of this essay could be shown to be wide of the truth depending on the results of the current investigations, so don’t take it too seriously…

Mars formed from the material in the solar nebula and reached its present size by 4.6 billion years ago (gigayears ago; Gya) ; the amount of water on the early planet is unknown, but there are two main options; either Mars had a similar amount of primeval water to the Earth, or it may have had somewhat less; much of the early waterin this region had become bound into bodies known as planetary embryos, and if Mars encountered fewer of these objects it may have started out significantly drier.

The evidence from Spirit and Opportunity seems to indicate that water was relatively plentiful in the early period, so we now have to consider where this water has gone.
The first age of Martian history, from 4.6 Gya to 3.8 Gya has been labelled the Noachian period; the atmosphere, mostly CO2 and nitrogen was perhaps six times as thick as that on Earth today. Liquid water was possible in these conditions, despite the fact that the early Sun was as much as 30% less bright. So there may have been seas, and there are many water-associated features in Noachian period terrain. The core of Mars was still hot enough for a magnetic field at that time, so the effects of solar wind and hard UV on the atmosphere were lessened.

However there were many impacts during the Noachian; 200+ craters larger than 5km per million km^2; this was one reason for atmosphere (and water) loss- impact erosion.
Because of Mars’ lower gravity, the effect of large impacts was to expel volatiles into outer space; the fraction that exceeded escape velocity never returned. (This will have to be accounted for in any terraforming project which involves volatiles crash-landing on Mars- if the impacts are too energetic, the volatiles will escape to a greater or lesser extent).

A second mechanism for Martian atmosphere loss was hydrodynamic escape; the early planet still contained a lot of the primeval hydrogen from the solar nebula; this will have been expelled by volcanic outgassing as it rose through the semimolten interior; a lot of hydrogen in the atmosphere would make it less dense, so the whole atmosphere would swell, and gases of all kinds would be driven off at the top of the swollen atmosphere; another way of looking at it is that hydrogen quickly boils off, but drags some of the other atmospheric components with it.

By the end of the Noachian, when impacts became less frequent and the magnetic field disappeared as the core cooled down, the atmosphere was down from 6 atmospheres to 0.06 atmospheres; liquid water would no longer have been possible.
Now the magnetic field had gone, the solar wind could rip away at the top of the atmosphere; this very variable effect is sometimes known as sputtering.
Additionally the hard UV from the early Sun (although the sun was less bright, it was smaller and hotter- so more UV) could strip water in the atmosphere into oxygen and hydrogen by photolysis; the hydrogen would escape, dragging other gases with it; the oxygen would combine readily with the rocks of Mars, forming sulphates, haematite, perhaps carbonates.

By these processes, impact erosion, hydrodynamic loss, sputtering and photolysis, the atmosphere of Mars eventually reached its current level of 0.006 x Earth’s. However the water loss will have been drastically reduced once the atmosphere was no longer thick enough to produce a greenhouse effect; when it got too cold the water will have turned to ice, which is much less volatile. In fact is is quite possible that much of Mars’ water is still there; as ice it would be incorporated into the rock as part of the solid matrix, or far underground as liquid water; the surface is freeze dried, and evidently very salty, though chorine seems to be scarce- the salts are mostly sulphates… but the loss of water to surface sinks seems to have been a major mechanism of water loss from the surface. One estimate says that half of the water left at the end of the Noachian is still there.

In other words, much of the water may still be there, buried deeply. During the later Martian periods, the Hesperian and Amazonian, it seems that combinations of orbital cycles and axial tilt have periodically brought liquid water to the surface; it may be possible to achieve this by artificial means, particularly using positive feedback mechanisms, and bring Martian water to the surface again.
 
Re: Water loss from Mars

Eburacum45 said:
It certainly seems likely that Mars had a lot of water at some point; if I may, I would like to give a little prehistory of Mars, given the evidence available before the Spirit and Opportunity landings.
...
Yes, yes! But, where's the OIL?

There must be some evidence of oil bearing strata up there. The sooner Barsoom Crude comes online, the sooner the wheels of industry can start turning again! Dick Cheney's old company, Harkonnen, must surely be on the case already?

Come on, show us the money!

:D
 
Has it ever ocured to you that one of the reasons for the (supossed) silence about living organisms in Mars is based on commercial interest? I was thinking, what would groups like Greenpeace say if there´s life in Mars right now? They would want its ecology protected and would be against any destructive explotation of martian natural resources. And that would not be a very nice thing for all those companies and groups of interest in the U.S. government. They could try to hid all evidence about life in Mars, in order to keep it secret enough time, at least until the explotation and terraforming processes in Mars kill all native life and they can sell real state and Mars made products.

Okay, now, seriously, what do you think?
 
Mars had water.
It's gone. Probably evaporated. Some in the ice caps.

Was it supposed to stick around, hovering outside the planet, waiting for us to come to it?


As an analogy, is Io (the moon) too small to have volcanos? Why does it have volcanos then? Io disperses its lava directly into space, btw. And to my knowledge, the lava hasn't stuck around waiting for us. :)
 
Is it just me, or does the whole big show NASA put on to announce "oh there was water by god!" seem like an ENORMOUS cop-out? Honestly, who DIDN'T already know that there was liquid water on Mars? This is something that's been established time and time again. There was no reason for NASA to hype that up as much as they did.
 
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Interesting news...

WASHINGTON, March 23 (Reuters) - NASA's Mars rover Opportunity is parked by the shore of what used to be a salty martian sea, scientists reported on Tuesday.
"We think Opportunity is now parked on what was once the shoreline of a salty sea on Mars," said Steve Squyres, principal investigator for the science payload on Opportunity and its twin Mars exploration Rover, Spirit.
Scientists have long seen signs of liquid water on Mars, and the rovers' mission was to investigate areas believed to have been covered with water long ago. If there was water, theorists believe, there might have been life on the Red Planet, Earth's next-door neighbor.
This is the first time, though, that scientists have concrete evidence -- new data from the rovers' analysis of the Mars rocks themselves -- that water might have flowed on the martian surface.
"This dramatic confirmation of standing water in Mars' history builds on a progression of discoveries about that most Earthlike of alien planets," said Ed Weiler, NASA associate administrator for space science.
"This result gives us impetus to expand our ambitious program of exploring Mars to learn whether microbes have ever lived there and, ultimately, whether we can," Weiler said in a statement.
The Mars rovers can do more than take pictures and beam them back to Earth. They also carry three different scientific instruments that can analyze the composition of various rocks and a grinding tool that can drill down under the surface.
Opportunity has been roving across the seemingly barren martian surface since January and is now working with rocks that were once covered with a rippling saltwater sea, the scientists said.
STANDING WATER
Opportunity's controllers plan to send it out across a plain toward a thicker exposure of rocks in the wall of a crater to see if they can find more evidence of standing water.
So far, scientists point to patterns in some finely layered rocks that indicate they were shaped by ripples of water at least 2 inches (5 cm) deep and possibly much deeper. This water was flowing at a speed of 4 to 20 inches (10 to 50 cm) per second, according to John Grotzinger, a member of the rover's science team.
The patterns come in distinctive smile-shaped curves characteristic of water's impact on rock, rather than wind erosion, he said.
Opportunity's current location might have been a salt flat when these rocks were forming, and might have been occasionally covered by shallow water and sometimes dry. On Earth, this type of environment can have water currents that produce the ripples seen in the Mars rocks.
The rover has also detected chlorine and bromine at the site, and the presence of these materials also suggests a martian salt flat that occasionally was underwater.
Scientists reckoned the rocks at the site had -- at the very least -- soaked in mineral-rich water, perhaps underground water, after they formed. But increased assurance that bromine was present strengthens the case for flowing water on Mars' surface.
 
The Frog said:
Mars had water.
It's gone. Probably evaporated. Some in the ice caps.

Was it supposed to stick around, hovering outside the planet, waiting for us to come to it?


As an analogy, is Io (the moon) too small to have volcanos? Why does it have volcanos then? Io disperses its lava directly into space, btw. And to my knowledge, the lava hasn't stuck around waiting for us. :)

And a virtually unlimited supply of volcanic material in it's interior then, I presume?
 
lordshiva said:
And a virtually unlimited supply of volcanic material in it's interior then, I presume?

Don't remember the last time I heard of a non-stop-eternal-lava-spouting volcano, but if that's the case, then yes, it must be gnomes inside.
 
Dead Sea: Saltwater on Mars

Story

Dead Sea: Saltwater on Mars

[ THURSDAY, MARCH 25, 2004 02:17:24 AM ]

WASHINGTON : Mars was once a much warmer, wetter place, with pools of saltwater that sometimes flowed across the surface, scientists reported on Tuesday.

Analyzing findings from sedimentary rocks explored by the rover Opportunity, the scientists said the rocks now appeared to have formed under a shallow bed of softly flowing water near a shoreline not, as formerly seemed possible, through seepage from underground. It was the first concrete evidence that water might have flowed on the Martian surface, and it provided new hints that life may have existed there.

“We think Opportunity is now parked on what was once the shoreline of a salty sea on Mars,” Dr Steven W Squyres of Cornell University , principal investigator for the science payload on the Opportunity and its twin Mars exploration rover, Spirit, said at a news conference here at NASA headquarters.

“If we are correct in our interpretation, this was a habitable environment,” Dr Squyres went on. “It’s a salt flat. These are the kinds of environments that are very suitable for life.”

He said there was still no evidence that life existed at the site, and the Opportunity does not have the instruments to hunt for microscopic fossils. But rock formed from sediments from evaporating standing water, like those at the site, “offers excellent capability for preserving evidence of any biochemical or biological material that may have been in the water,” he said.

Dr Edward Weiler, Nasa’s associate administrator for space science, said that when researchers first announced on March 2 that the Opportunity had found rocks that formed in the presence of water, there was some indication that the water pooled on the surface. But to be sure that they were interpreting the data correctly, Dr Weiler said, they sent it to several outside experts for review before Tuesday’s announcement.

One of those scientists, Dr David Rubin, a sedimentary expert with the US States Geological Survey, said he was shocked when he received the Mars pictures from Nasa. “I was astonished,” Dr Rubin said. “They looked like sedimentary deposits found at a beach on Earth.”

(NYT News Service)
 
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replies to responses

To all:

It's apparent that the point I was trying to get across has not been perceived. I keep being informed that Mars doesn't have an atmosphere because it has leaked off into space, over time. I am aware of the suggestion that Mars' atmosphere escaped over time, as a result of solar heating, and Mar's low gravity.

But that is not the point I was making!

I was saying that the condition of having a large, long-lasting ocean is not compatible with the description for the development of Mars!

In order to have an ocean, Mars will have had to have had a significant atmosphere. And, for the ocean to have done what is attributed to it, Mars will have had to have had that atmosphere for a very long time. But that means that, whatever acted to deprive Mars of an atmosphere must not have been working then as it is now. But it also suggests that whatever caused Mars to lose its atmosphere, essentially, just started up.

When Mars was being formed, it was very hot, certainly too hot for liquid water to remain on the surface, but, almost certainly too hot, too, for gases to be held by the light gravity of the planet. Significant atmosphere build-up does not seem to have been likely to occur until after the planet cooled. In other words, Mars will have been in a condition very close to what it is, today, except that it will have a thick atmosphere and oceans of water. For a long time, the atmosphere will have remained stable, and the oceans will have persisted. Persisted for the apparently many hundreds of millions of years it took to build up the evidence of mineral deposition that is claimed, today. And it, likely, did occur for many hundreds of millions of years, maybe even more than a billion years. This can be considered likely, since signs of the supposed presence of the oceans persists to today. In general, it takes as long to remove signs of a physical process as it takes to produce them. So the length of time wind abrasion has been working against the signs of the ancient oceans, likely, has not lasted longer than the oceans themselves lasted. This could suggest that the oceans persisted for up to two and-a-half billion years or more! And all this time, the atmosphere of Mars remained, evidently, quite stable and dense.

Then, things suddenly changed, and Mars' atmosphere leaked away.

Some suggest that the end of volcanism on Mars led to the leaking away of the atmosphere. Volcanoes, presumably, provided carbon dioxide, sulfur dioxide, and so on, into the atmosphere, replenishing what may have been leaking away, over time, previously. It was the volcanoes, supposedly, that kept the atmosphere constant on the planet, during the time it had its oceans. When volcanism stopped, the atmosphere started bleeding into space, lowering pressure, and causing the oceans to boil away.

Placing it all on volcanoes, though, has distinct disagreements with the facts.

Titan, the satellite of Saturn, has a diameter of about 3,200 miles, about three-fourths of Mars'. Yet Mars has a surface pressure of about 6.7 millibars, while Titan's pressure is about 1.5 bars, one and-a-half times that of earth! Titan's atmosphere is more than two hundred times as dense as Mars'! Yet Titan shows no sign of volcanism.

Many will be tempted to say that Titan is not in the same type of situation as Mars. Titan is at least six times as far from the sun as Mars, so the solar heating is not as strong as Mars feels. But Titan is, likely, affected by radiation, trapped in the magnetic field of Saturn.

But Venus is just as anomalous, in terms of its atmosphere. About the same size as earth, Venus is about 30% closer to the sun, yet has a pressure of 90 bars, 90 times earth's! And Venus has no sign of volcanism for much, if not most, of its history, either! Wherever it got its atmosphere from, it does not seem to have needed such wholesale volcanic activity to maintain it! Even though it is less than half Mars' distance from the sun!

So lack of volcanic activity cannot be represented as the explanation for Mars' atmosphere having leaked away. Which means that the reason for Mars having retained an atmosphere long enough to develop and maintain oceans still needs to be recognized.



Julian Penrod
 
I'm not quite sure what your point is. I' not sure wht there needs to have been a rapid change in Mars' atmosphere. If the atmosphere leaked away slowly then the seas could have gradualy shrunk in the same way that the Caspian ans Salt Lake Utah have. Mars may gain a thicker atmosphere at certain times - during periods of volcanic activity then slowly loose it again.

As for Venus. I understood that that planet showed lots of signs of vulcanism - but has non of the processes of subduction that remove cabon dioxide from Earth's atmosphere.
 
The Martian seas, if they existed, were all gone before 3.8 billion years ago (although the precise timescale is being revised all the time); these seas might have been quite large, or only sulphurous lakes.

it was only possible for seas/liquid water to exist while the atmosphere was dense, and originally it seems to have been denser than the present atmosphere of Earth. But over the course of a few hundred million years this atmosphere was lost, and so the water could no longer exist as liquid at the surface; a large proportion seems to have disappeared into the crust, while therest was lost to space.

To recap, Mars did lose its water long ago, but was wet for many millions of years.

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Io is constantly heated by tidal flexing, so is constantly replacing its own surface with lava- a little of the mass of this moon is lost with each eruption, but there is plenty of this moon left before it evaporates completely.
 
Assumptions are all we really have in this case. There are laws of physics so we can narrow down what likely happened to the surface water on Mars. But remember there are ancient oceans and lakes on Earth that have disappeared. We don't assume that some unknown force caused Earths ancient oceans to disappear so why think that of Mars.
We are relying on the same type of rock data to prove existence and disappearance of water on both planets.
 
For water to remain a liquid a certain amount of atmospheric pressure needs to exist.

Once Mars atmospheric pressure reached a certain point, all the remaining seas and liquid water would boil off and escape as gases.

I imagine Mars continually lost atmosphere and water, until a point was reached, and the seas boiled off quickly (geologically speaking).

Sorry if this has been said.
 
I was just trying a thought experiment:

If you dumped a large body of water onto Mars as it is it would begin to evaporate. After a while there would be enough water vapour in the atmosphere to maintain the oceans. As the water vapour was slowly lost due to low gravity and water molecules being split into hydrogen and oxygen the oceans would evaporate to maintain the atmospheric pressure until they were all gone. The hydrogen would be lost into space, the oxygen would react with iron in the crust of Mars.

I'm not sure how long such a process would take.
 
Any atmosphere we give Mars would be lost fairly rapidly in geological terms; over a period of several million years.

How long do you want to live there?

If the answer is 'a lot longer than that'
then I would recommend one of our handy-dandy Worldhouses to prevent atmosphere loss...

http://www.orionsarm.com/civ/Worldhouses.html

or you can just keep importing water from the outer solar system- eventually you will lose it all, which would be a shame.
 
Is that a puddle at the bottom of the pic, or just flat super fine sand ?
 
Jack Ruby said:
Is that a puddle at the bottom of the pic, or just flat super fine sand ?

It's difficult to tell with the available information. However, if you look closely the substance in the 'puddle' appears to be translucent. I.e. It seems you can see the side of the puddle through it.

There appear to be JPEG compression artefects visible in the 'puddle' which doesn't help to figure out what we're seeing.
 
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