Mars atmospheric loss and lifetime

Terraformer · 2018-08-01 07:29:14

Current atmospheric loss to the solar wind is 100g per second. That's 8.64e3 kg per day, or ~3.2e6 kg per year. The current Martian atmosphere has a total mass of 2.5e16 kg. At current rates of outgassing, the Martian atmosphere would double over 10 million years.

Total losses to the solar wind over 10 million years: 3.2e13.
Total gains from outgassing over that time: 2.5e16.

Conclusion: though I wasn't expecting it, if Mars is left alone for the next 100 million years it will build up an atmosphere all by itself that's suitable for hardy surface lifeforms. More near-term, if solar stripping is the dominant loss mechanism, any atmosphere we put there should stay there over geological timescales. So we don't have to worry that terraforming using indigenous resources will simply rid Mars of it's precious volatiles.

knightdepaix · 2018-08-01 09:21:42

Terraformer wrote:

Total losses to the solar wind over 10 million years: 3.2e13.
Total gains from outgassing over that time: 2.5e16.

What is the rate of increasing luminosity of the sun? In many billions of year, the sun will become a red giant and likely engulf Earth. Before that Earth will have experienced a runaway evaporation of the ocean. To reply to your post, the OP can make a graph of a few lines and curves
1) loss of Martian atmospheric mass over time due to increasing strength of solar wind. Loss of mass over time is thus used as a scale for the increasing erosion by solar wind. (kg year-1)
2) gain of outgassing over time over temperature (kg year-1 K-1)
3) increase of sun luminosity over time
4) increase of radiation by sun on Mars over time
5) rate of warming by global warming chemical agents (perfluorocarbons, for example) (K year-1)

At some parts of the crossings of those lines and curve, the OP may find windows of opportunities to terraform Mars. Then the OP may suggest adding more chemical agents or less, or other measure to monitor the terraforming process.

However, reviving the Martian magnetosphere or creating artificial is assumed. Can the effect of shielding solar wind by artificial means be graphed?

Last edited by knightdepaix (2018-08-02 08:04:23)

Void · 2018-08-01 12:43:47

On this topic, I often have noticed conflicting extreme articles claiming various things.

For instance this, which appears to support Terraformers assertions:
https://phys.org/news/2017-12-mars-atmo … solar.html
Quote:

Mars atmosphere well protected from the solar wind
December 8, 2017, Swedish Institute of Space Physics
……
"Despite stronger solar wind and EUV-radiation levels under the early Sun, ion escape can not explain more than 0.006 bar of atmospheric pressure lost over the course of 3.9 billion years," says Robin Ramstad. "Even our upper estimate, 0.01 bar, is an insignificant amount in comparison to the atmosphere required to maintain a sufficiently strong greenhouse effect, about 1 bar or more according to climate models."

So, the idea is, since geology strongly suggests that a significant atmosphere was there previously, where did it go?
1) Lost to space (Not according to the attached article).
2) It went underground.
3) The great Bombardment stripped it away.
http://www.bbc.co.uk/science/earth/eart … ombardment
Quote:

About 4 to 3.8 billion years ago a period of intense comet and asteroid bombardment is thought to have peppered all the planets including the Earth. Many of the numerous craters found on the Moon and other bodies in the Solar System record this event.
One theory holds that a gravitational surge caused by the orbital interaction of Jupiter and Saturn sent Neptune careening into the ring of comets in the outer Solar System. The disrupted comets were sent in all directions and collided with the planets. These water-rich objects may have provided much of the water in the Earth's oceans.
The record of this event is all but lost on the Earth because our planet's tectonic plate system and active erosion ensure that the surface is constantly renewed.

But wait, if these comets added water to the Earth, wouldn't they have added water to Mars as well? Well I am not sure.

Mars possibly had Oxygen in it's atmosphere 3.8 billion years ago?
http://www.sci-news.com/space/article01 … phere.html
Quote:

“The implication is that Mars had an oxygen-rich atmosphere at a time, about 4 billion years ago, well before the rise of atmospheric oxygen on earth around 2.5 billion years ago. As oxidation is what gives Mars its distinctive color it is likely that the red planet was wet, warm and rusty billions of years before Earth’s atmosphere became oxygen rich,” Prof Wood said.

Not strong evidence that for instance the great bombardment caused Mars to have a vaporized Iron atmosphere and all the water and atmosphere boiled off. The impact that caused Hellas must have heated the place up, but that much? Don't know.

And the impactors for Earth were supposed to have brought water (Although apparently water was present on both Earth and Mars before that.

This article talks about a Northern ocean, but may not give time notations:
https://en.wikipedia.org/wiki/Mars_ocea … l_evidence

So, where did this ocean go if the solar wind and UV did not get most of it?

……

I see so much conflicting data and opinions. I don't know what to think about Mars.

……

Similarly the Trapist system has conflicting information.
https://en.wikipedia.org/wiki/TRAPPIST-1
We are continuously told that such a system would have planets which would be in deep deep danger of being stripped of their atmospheres by a very active magnetic solar wind from a Red Dwarf star.

But guess what? Too much water?
http://www.astronomy.com/news/2018/03/t … pport-life
Quote:

TRAPPIST-1 system may have too much water to support life
The planets around TRAPPIST-1 are estimated to be between 15 and 50 percent water by mass — Earth is only 0.02 percent.

Granted the outer planets may be surfaced by water ice, and so resistant to stripping to a degree, but what about the inner ones? How do you have 15% to 50% water planets, and a solar wind that should have stripped away the atmosphere?

…..

And then then there is our Venus. Why doesn't it have an exposed rocky surface like Mercury?

Last edited by Void (2018-08-01 13:27:14)

SpaceNut · 2018-08-01 17:38:58

Millions to Billions of years is not going to happen as that means acumilated energy over that time to make the process happen...and that needs to be in a decade to make a mars viable for life....

JoshNH4H · 2018-08-01 17:50:51

If this is the case, why doesn't Mars have a thicker atmosphere already? I would expect outgassing to slowly fall over time as solar wind erosion remains roughly constant, meaning the atmosphere should (?) have settled into some sort of equilibrium by now

SpaceNut · 2018-08-01 19:11:25

The comet that flew by disturbed the magnetic field and atmosphere but Maven was not ready to capture it all....

Terraformer · 2018-08-02 02:40:07

I don't know what's going on with the Martian atmosphere. Those figures are all from NASA, so surely someone there will have noticed the discrepancy by now? It's a shame Midoshi isn't here to tell us more about the MAVEN results...

Void has suggested that there's some kind of mechanism to keep the atmosphere near waters triple point. It's possible. Maybe the atmosphere increases until it can sustain liquid water, then the water carries dissolved CO2 into the rocks and locks it up as carbonates, or freezes as clathrates, or it gets bound to the regolith, bringing the atmospheric pressure back down again until the mechanism ceases. Most of the time Mars would be dry and cold, but for brief (100k years?) periods of time it would have running water and lakes.

louis · 2018-08-02 05:57:49

where do you get that outgassing figure from? Do you have a quote? I presume you mean it's a natural form of outgassing???

Terraformer wrote:

Current atmospheric loss to the solar wind is 100g per second. That's 8.64e3 kg per day, or ~3.2e6 kg per year. The current Martian atmosphere has a total mass of 2.5e16 kg. At current rates of outgassing, the Martian atmosphere would double over 10 million years.
Total losses to the solar wind over 10 million years: 3.2e13.
Total gains from outgassing over that time: 2.5e16.
Conclusion: though I wasn't expecting it, if Mars is left alone for the next 100 million years it will build up an atmosphere all by itself that's suitable for hardy surface lifeforms. More near-term, if solar stripping is the dominant loss mechanism, any atmosphere we put there should stay there over geological timescales. So we don't have to worry that terraforming using indigenous resources will simply rid Mars of it's precious volatiles.

Terraformer · 2018-08-02 06:16:40

It's in the links.

louis · 2018-08-02 09:58:52

It's not in the first link. For all I know it could be on the tenth regressive link! Can't you just give the quote...the only reason I'm interested is I've never seen this claim before, I thought it was the case that losses were still exceeding replacement.

Terraformer wrote:

It's in the links.

Terraformer · 2018-08-02 10:07:03

The first link gives the loss rate, the third link gives the claim that outgassing would double the existing atmosphere in 10 million years, and the second link gives the mass of the Martian atmosphere.

According to qraal, Mars has possibly had periods in the past of running water:

Abundant signs of climate change exist all over the planet – sudden floods of water as ice melts have formed rivers all over the planet. But then the warming ends and the planet chills. The suspicion is that temporary warmings increase trapping of carbon dioxide by dissolving it in water, thus an “Impact Summer” is followed inevitably by the return of the Endless Winter.

Perhaps we can engineer a life form to stop the atmosphere from being lost again this way. But if it's the explanation for where the outgassing went, then it bodes well for terraforming. Maybe. If the carbonates aren't too bound. I don't know how much energy we'd need to liberate a CO2 atmosphere from them, but if we're lucky we won't have to, due to enough being trapped as clathrates.

RobertDyck · 2018-08-02 12:00:42

The textbook "Terraforming: Engineering Planetary Environments" cites 2 papers. One estimates simply sublimation Mars dry ice will produce surface pressure of 200 mbar, the other estimates 300. Both papers were before MGS, I would like an updated estimate. But 300 mbar is enough. Absolute minimum is 170 mbar for a human being to walk on the surface without a pressure suit, a strong athlete/soldier/pilot/astronaut in his/her prime, fit, with high altitude training, and breathing pure oxygen. 300 is good for everyone. Plants can withstand 100 mbar as long as they have plenty of water.

Point is we don't need to decompose carbonates.

Last edited by RobertDyck (2018-08-04 04:57:16)

Void · 2018-08-03 20:09:24

I am not sure I understand where the information on outgassing is. Can you help?

…..

Beyond that however, I think I have a question on probability's.....

Terraformer said:
Quote:

I don't know what's going on with the Martian atmosphere. Those figures are all from NASA, so surely someone there will have noticed the discrepancy by now? It's a shame Midoshi isn't here to tell us more about the MAVEN results...
Void has suggested that there's some kind of mechanism to keep the atmosphere near waters triple point. It's possible. Maybe the atmosphere increases until it can sustain liquid water, then the water carries dissolved CO2 into the rocks and locks it up as carbonates, or freezes as clathrates, or it gets bound to the regolith, bringing the atmospheric pressure back down again until the mechanism ceases. Most of the time Mars would be dry and cold, but for brief (100k years?) periods of time it would have running water and lakes.

So let me have a run at it again, with an extended query.

The Question: What is your gut feeling on the probability that...
1) The human race is able to send probes to planets to examine them in much better detail, starting in the 20th century.
2) The theory of the solar wind and UV stripping the Martian atmosphere implies that since Mars had abundant water, the atmosphere has been stripped away, perhaps not at a continuous rate, but at a continuing loss of atmospheric mass (Except for occasional volcanic eruptions). So for Item #2, what is the likelihood that this atmospheric stripping happened at such a rate with such a timing that indeed just when we were there to measure the atmospheric pressure in the 20th century, after ~4.5 billion years, the air pressure is an average just below that of the triple point of water. And in the low spots it is just barely above the triple point of water. What are those odds?
~4.5 billion years, ~triple point of water on Mars, and humans just become able to measure it. Hmm..... Some coincidence!
3) But now lets add a Venus question. Why hasn't the atmosphere of Venus been stripped away? It does not currently have an appreciable geomagnetic field. It's atmosphere is largely protected by inductive reactance in it's outer atmosphere. An induced magnetic field. The exceptions that I am aware of are Hydrogen probably leaks away (From all terrestrial planets), and Oxygen for Venus. But the Oxygen leakage may very well be because a electrostatic field lifts the Oxygen to where the solar wind can strip it. The electrostatic field is so intense because the atmosphere of Venus is so dry overall.

So, an argument supporting the notion that the reason could be that Venus has a magnetic field that flips, and that it is between flips.

Summing up #1, #2, #3, what are the probabilities that the human race achieves awareness, at the same time that the solar wind strips the Martian atmosphere down to the pressure near the triple point of water, and also the magnetic field of Venus is between flips?

Doesn't it seem plausible that indeed there may be a mechanism that maintains the Martian atmosphere typically near the triple point of water, and that Venus may not really have a flipping magnetic field. And if this were true, shouldn't we have doubts about the solar wind always being able to strip the atmospheres off of planets without a Earth type magnetic field. I think I want the other side to present some evidence, and Mars having a thin atmosphere is not sufficient proof.

Done.

Last edited by Void (2018-08-03 20:30:27)

Terraformer · 2018-08-04 02:05:01

The second link is to a NASA site that claims outgassing would double the Martian atmosphere in 10 million years. The third is to a NASA site that gives the mass of the Martian atmosphere.

SpaceNut · 2018-08-09 18:16:21

This relates to the megosphere that solar wind is reshaping....
https://www.nasa.gov/feature/goddard/re … on-on-mars

qraal · 2019-03-09 19:21:14

The MAVEN mission has measured the loss rate and extrapolated back through time it's quite substantial. There's several processes, chief of which is Jeans' loss of hydrogen to space.

Mars Atmosphere Loss Rates – Truth vs Truism

The total CO2 is ~78 millibar and the total Hydrogen about 25 metres of water equivalent. But that's assuming both the Solar Wind and Solar EUV/XUV remained constant. Both of those energy sources to the Exosphere were much, much higher in the past.

If Mars is out-gassing quicker enough to double 6 millibars in 10 million years, I suspect a counter process would be geosequestration by reactive chemistry in the regolith, maintaining the atmosphere at near water's triple point. A warmer, wetter Mars just speeds up the draw down. The trick, for terraformers, will be developing counter-cycles of bacteria or chemistry.

IanM · 2019-03-09 19:47:29

The entire reason there is (long-term) life on Earth is due to plate tectonics and a cycle of silicate weathering. A simplified version is this: volcanoes emit CO2 from the mantle, which when it increases in the atmosphere warms the planet up, but that warming increases the rate of silicate weathering, a process that consumes CO2. On one hand, the weathering produces calcium carbonate from the CO2, which is ultimately subducted into the mantle, while on the other the decrease of CO2 cools the planet, slowing down the weathering and allowing CO2 stock to recover, ultimately warming the planet once again and providing a negative feedback on temperatures and keeping them in a fairly stable band over geologic time. (That's why we were ultimately able to escape the Snowball Earth even though the large ice cover increased albedo.)

Mars doesn't have plate tectonics. I've heard of a plan to rotate Pluto around it to heat the core up with tidal forces to produce it (or something to that effect), but that's far off even for terraformation. Biotic processes would be important for the carbon cycle, but we need to find a way to dispose of the buildup of dead organic material over time. (Perhaps the excess weight of it could put enough pressure on the mantle and core to heat up, but that seems to be wishful thinking.)

As for an atmosphere we're going to need a large source of nitrogen to form the "inert" (neither greenhouse nor phase-changing at relevant parameters) gas. To achieve the same pressure at sea level as on Earth we'd have to make it about 85% of the weight of Earth's (to account for Mars's lower surface area and gravity) if my calculations are correct. Earth's atmosphere is about 78% N2, so let's say Mars's would be 75% N2 to account for the slightly-higher need for greenhouse gases to warm it up more. Assuming this is all by mass, I reckon that Mars will need approximately 3.3*10^18 kg of N2 gas. I'm not sure how much nitrogen is available on Mars in the regolith, etc., but on Earth the vast majority of Nitrogen in any form is in the atmosphere, so assuming the same is true on Mars that's quite a lot of N2 we'd have to find somewhere.

There could be other inert gases, however. Pretty much anything other than greenhouse gases, water, or O2 could be appropriate, although heavier is better to reduce Jeans escape.

elderflower · 2019-03-14 06:21:31

Mars atmosphere contains about as much Argon as Nitrogen. Argon will do just as well as an atmospheric component except it can't be fixed biologically for use by plants.

IanM · 2019-03-16 22:20:41

elderflower wrote:

Mars atmosphere contains about as much Argon as Nitrogen. Argon will do just as well as an atmospheric component except it can't be fixed biologically for use by plants.

That's true, I'm just wondering how the amount of either material can be increased to reach roughly Terran values for a fully-terraformed atmosphere. The thing with both materials is that on Earth the vast majority of them occur in the atmosphere, and assuming the same is true for current Mars (i.e., no significant source of Ar or N2 locked up in the regolith) it's hard to imagine how they can be produced in situ without needing to import them (on Earth Argon is produced from Potassium decay, but I don't think such process is extant on Mars). I do think N2 is more important, both for biological fixation and the fact that an N2 molecule is lighter than an Ar molecule and as said earlier that a terraformed Martian atmosphere would have to be lighter than the Terran atmosphere.

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#1 2018-08-01 07:29:14

Mars atmospheric loss and lifetime

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Re: Mars atmospheric loss and lifetime

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