A Soggy World ... Maybe! - Looking at a Globe of Mars

Shaun Barrett · 2002-01-21 01:23:14

It seems that almost every article you read about Mars is based on the same premise, that Mars was once warm(er) and wet. The main problem with this hypothesis being that there seems to be no way to model an early Mars with enough atmosphere and enough insolation (solar input) to get the surface temperature above zero.
You can imagine a 5 bar atmosphere of CO2 soon after accretion of the planet, which would provide a nice cosy greenhouse effect .... IF there were enough heat coming in from the sun for the atmosphere to trap! But then you have to contend with the "dim young sun" problem. (I know, I know ... it sounds like an item on a chinese menu!) This refers to the fact that 3 to 4 billion years ago, the sun was only putting out about 70% of its present heat and light. Even today, with 43% of the insolation Earth gets, Mars is a very cold place. When you factor in the 70% output, early Mars was only getting 30% of the warmth we are basking in today.
If you suddenly throttled back solar output arriving here on Earth today to just 30% of the norm, we would be plunged into the mother and father of an ice-age from which we would never recover. So, even with that 5 bar CO2 atmosphere we conjured up, it still seems impossible to produce a climate on early Mars which could be deemed anything but freezing cold!
Exotic solutions have been put forward to try to get around this difficulty, including a dense cabon-dioxide atmosphere with high-altitude clouds of CO2 crystals. According to theoretical models, this would be a very effective "blanket" for Mars which would keep the surface warm enough for liquid water to exist. The only drawback being that Mars would have been continuously overcast for many millions of years.
It seems to me that making up exotic theoretical models in an attempt to explain the data, probably means that you have the wrong data or that you have the right data but not enough of it!
Then there's this guy Hoffman from Australia! He thinks Mars was never warm and wet. He maintains that it was always bitterly cold and bone-dry and that its surface features, so reminiscent of water erosion, were caused by floods of liquid CO2 mixed with rock and dust! No water necessary. And he must have developed this idea to a significant degree, too, because at one seminar he apparently had more than half the "watery Mars" advocates doubting themselves.
But then again, I have a magnificent globe of Mars which I bought on the net from "Sky and Telescope". It is a topographical globe, color-coded to depict the relative height of the terrain, with the high ground in shades of orange and red and the lowlands in green and blue. It is based on the most recent Mars Orbiter Laser Altimeter (MOLA) data and is therefore highly accurate. I would recommend it to anyone with an interest in Mars.
The point of all this is that when you look at this globe with its valleys, channels, and flood-plains, it just screams "WATER"! Large areas look 'smudged', just like a sand-castle that has been washed over by a wave! Craters in the northern basin have breached walls and highly eroded rims; some appear to be so buried in sediment as to be almost too feint to see. The whole planet gives every indication of having had water on its surface. And I don't mean some paltry amount of water! I mean the whole place must have been awash with it!! Buy,steal, or borrow one of these globes and have a really good look at it; I think you'll have to agree we're talking about millions of cubic kilometres of good old H2O here! Not liquid CO2. If it looks like a duck, waddles like a duck, and quacks like a duck; chances are it is a duck! And when you see this globe, you'll be able to TASTE the water on Mars!
So where does that get us? Back to square one. I know Mars had to be warm and wet; maybe it even had extensive precipitation for lengthy periods in its history. But how do we explain it? Could Mars' internal heat have somehow contributed to a warmer climate? Could there have been more powerful greenhouse gases in the early Martian atmosphere?
As to the fate of all that water, I'm afraid much of it has been lost to space. But not all of it. There may still be enough in vast aquifers to create lakes and even small seas if the surface were warmer and the air denser. Stand by for more data from Mars Odyssey which, a few weeks ago, may have found hints of large quantities of water under Vastitas Borealis.
Can anybody add to this Post and maybe enlighten us all as to this vexed question of water on Mars?

RobS · 2002-01-22 00:28:59

Alas, I have not followed the research in detail for about 20 year, but I gather that a "cold wet Mars" model is also being considered by many people. The large outflow channels could have been formed not by a single flood of a few days, but a constant flow of ground water over many years that freezes as it flows, choking its own channel with ice and therefore forcing it to make the channel wider. That's an argument some have made. A few outflow channels appear to flow uphill, which is possible under a glacier. There appear to be eskers on Argyre Planitia, which are channel deposits formed under a subglacial river.

So it may be that in the first billion years or so, Mars was close to freezing, but usually below. Volcanic activity was much greater than today, with millions of square kilometers being repaved by basalt flows. The flows brought heat to the surface as well as water. So water accumulated in the regolith partly as vapor perculating upward, partly as snow (it may have snowed; this would explain the few gullies that appear to come from meteorological sources) and when volcanic activity occurred in an area vast quantities of permafrost melted, oozed out their water, sometimes gushed out their water. Some of the Mariner Canyons were filled with lakes; the horizontal strata of lakebed deposits seem to be visible in some pictures. As Mars aged, the volcanic activity decreased, more and more water and air escaped into space, and the episodes of water flow and even precipitation grew less and less.

A billion years or so from now, when the sun is 40% brighter than today, Mars may have a brief renaissance, then the atmosphere leaks away at a faster rate and we have a "warm dry" Mars model instead!

-- RobS

Alexander Sheppard · 2002-01-23 11:15:33

40% brighter? Are you sure? I thought it was more like 10%. Mabye 40% after the sun has almost reached red giant stage, but not in a mere billion years...

RobS · 2002-01-23 12:18:39

I'm not sure whether it is 40% or 10%, but I was surprised to read something recently that said the Earth could face runaway greenhouse effect and head toward a Venus-like future in a mere billion years. I wonder whether 10% would do that. But I am not sure what the projection of future brightness increases is. Thanks for asking.

RobS

Shaun Barrett · 2002-02-27 06:57:30

Yes, I read the same thing about Earth being heat-sterilised in a billion years.
I was amazed, too, because when you consider that life has existed here for some 4 billion years, only having 1 billion to go doesn't sound like much! It's like Earth is in old age already.
But, lately, I'm sure I heard somewhere the opinion that life on Earth had maybe 3 or 4 billion years to go before the sun becomes too hot. Someone has to be making mistakes with their arithmetic! But who is wrong?
Incidentally, according to one source, when Earth becomes unlivable, Mars should be quite pleasant for roughly 500 million years. That should give us ample time to put an atmosphere around Ganymede or Europa! Then, of course, there's always Titan!

AndyM · 2002-02-27 13:18:42

It may be besides the point, but I don't think you can say that life has existed on Earth for 4 billion years. What most of us would call life has only existed for the past 600 million years. Prior to that point, we only have evidence of single cells and they didn't develop a nucleus until about 2 billion years ago.

Shaun Barrett · 2002-02-28 05:07:15

I sympathise with your point of view. It's difficult to get enthusiastic about 3.5 billion years worth of nothing more exciting than mats of blue-green algae! And, when you put it your way, we're not even half way through the reign of macroscopic multi-cellular organisms; an altogether more optimistic way of looking at it!!
But then again, if life is rare and precious, I guess we really need to acknowledge even the earliest and most primitive life-forms; uninspiring though many people would rate them. And that heat sterilisation event is just so final! It seems like an obscenity to contemplate the end of a planet as beautiful as this one; at least in terms of its life-nurturing ability.
So I'm hoping the 3 billion year people have got it right and that the 1 billion year people wouldn't know accurate arithmetic if it jumped up and bit them on .... a really tender spot!!
If anyone out there knows the real truth about the sun's projected evolution, and how much time life on Earth has left, could you please enlighten us?
:0

Phobos · 2002-03-01 18:39:38

Personally, I'd find it fascinating if there turned out to be blue green algae, or just a few alien bacteria burrowing around on Mars. If it exists on both Mars and Earth, then the possibility is very good that life is a common occurance throughout the rest of the universe. It would be especially interesting to see how different the life on Mars would be from Earth life. Would it have DNA sequences like we do? Would it use ATP as a power source? We could see a totally new way in which life
can arise and operate.

rgcarnes · 2002-03-02 18:59:53

Phobos may have hit upon a very important aspect of life, even cyanobacteria, which might be on Mars.

It seems that each of our cells, human cells, contain organelles called mitochondria. These things contain DNA and we all inherit our mitochondrial DNA from our mothers. This DNA does not take part in the sharing and shuffeling of genes during sexual reproduction, and we all seem to have, according to the sources I've read, the same mitochondrial DNA.

What makes this especially interesting, is that the structure and form of the mitocondria are almost indestinguishable from cyanobacteria. The thought is that some time in the development of higher life forms some strain of cyanobacteria were incorporated as essential organelles within each cell.

Would alternate developments be available on Mars?

I realize the life aspect of the original topic seems to have taken over, sorry if it's inappropriate.

Rex G. Carnes

Phobos · 2002-03-03 16:32:12

If we find life that's very similiar to ours on Mars, it might lend credence to the theory that life was transferred from Mars to Earth or vice versa. Even though I think such events are far fetched, I'm hoping that if we do find life on Mars that it turns out to be organized much differently than Earth's life so there will be no question that life started independently on both planets.

Shaun Barrett · 2002-03-04 06:58:33

If they did find indigenous Martian life with a wholly independent origin, you can bet the "greenies" would be out in force (perhaps rightly) to ban any further interference from Earth with the Martian biosphere.
You could kiss goodbye to any further manned missions, and don't even think about terraforming!! Mars would be declared the first planetary national park; but NO TOURISTS!!
No, the last thing we need is exotic alien life on Mars. You probably know my views about life on Mars by now from other posts and replies I've made. So you know I have virtually no doubt that Martian life will be closely related to Earth life; having shared the same origin.
I admit, Phobos, your Martian life would be much more interesting than mine. But I want Mars terraformed; not turned into a museum!

RobS · 2002-03-05 17:36:34

To follow up on two minithreads in this discussion:

1. I read somewhere about a year ago that we don't have to worry too much about the earth heating up so much that it becomes sterilized because the process occurs so slowly, we can use an asteroid and a zillion series of gravity assists to move the Earth (and Mars) into orbits more distant from the sun. As you may know, space craft get gravity assists all the time from planets, causing them to speed up or slow down, and the planet to do the opposite (much less noticably, because of the planet's enormous mass). A large asteroid--perhaps 50 miles across--could be put into an orbit that passes between the Earth, Jupiter, and Saturn periodically, stealing speed from the later two and giving it to earth through carefully crafted gravity assists. Quite clever. We'd need to move the Earth a lot, but we have a billion years to do it.

2. Regarding Martian and Earth life. Considering that thousands of tons of Mars have been blasted into space and landed on Earth, and hundreds of tons of Earth have been blasted into space and landed on Mars, over the last few billion years, for all we know, life may have originated on Mars and got transported here by a meteor impact. It is possible we are Martians and that when we visit Mars, we will find ancient, primitive cousins in some steam vent. It is also possible that life originated in Venus first, was sent to both the other two worlds by asteroidal impacts, and then was wiped out on Venus. We may never know, but finding life on Mars with substantial biochemical similarity would be indication something was transported somewhere, and Mars will have older rocks than the Earth, so it may tell us whether life originated there or not.

But we have to send people there to do this research; it'd take robots a hundred years.

-- RobS

Adrian · 2002-03-06 07:35:52

The idea of moving Venus or indeed any planet using gravity assists is relatively new and I actually came across a thread on rec.arts.sf.written about it - here's the top of the thread, and some interesting comments by Geoffrey Landis.

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#1 2002-01-21 01:23:14

Re: A Soggy World ... Maybe! - Looking at a Globe of Mars

#2 2002-01-22 00:28:59

Re: A Soggy World ... Maybe! - Looking at a Globe of Mars

#3 2002-01-23 11:15:33

Re: A Soggy World ... Maybe! - Looking at a Globe of Mars

#4 2002-01-23 12:18:39

Re: A Soggy World ... Maybe! - Looking at a Globe of Mars

#5 2002-02-27 06:57:30

Re: A Soggy World ... Maybe! - Looking at a Globe of Mars

#6 2002-02-27 13:18:42

Re: A Soggy World ... Maybe! - Looking at a Globe of Mars

#7 2002-02-28 05:07:15

Re: A Soggy World ... Maybe! - Looking at a Globe of Mars

#8 2002-03-01 18:39:38

Re: A Soggy World ... Maybe! - Looking at a Globe of Mars

#9 2002-03-02 18:59:53

Re: A Soggy World ... Maybe! - Looking at a Globe of Mars

#10 2002-03-03 16:32:12

Re: A Soggy World ... Maybe! - Looking at a Globe of Mars

#11 2002-03-04 06:58:33

Re: A Soggy World ... Maybe! - Looking at a Globe of Mars

#12 2002-03-05 17:36:34

Re: A Soggy World ... Maybe! - Looking at a Globe of Mars

#13 2002-03-06 07:35:52

Re: A Soggy World ... Maybe! - Looking at a Globe of Mars

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