Loss of atmosphere and liquid water on Mars

From the geologic evidence, we know that Mars once had a thicker atmosphere and huge bodies of liquid surface water. Does anyone know when the atmosphere and bodies of liquid surface water for the most part disappeared? Mars atmosphere is currently only 1/100th as dense as the atmosphere on Earth. Did this occur slowly over time, 3.8 billion years ago, or within recent geologic history (100 million years to present)? The current theory suggests that much of the atmosphere was lost 3.8 billion years ago with the remainder being lost slowly over time.

[link]

Hey Marsman - I was looking for a graph depicting the boiling of water as a function of pressure. Thought that would be useful to your analyses. Although this does not go below 50 degrees F and 3 PSI what is important to note is that liquid water can not exist on the surface of Mars. Either it is frozen or in a vapor. It simply gets too warmpm the equator. I've seen a number of pro-bio people state that there IS water there now but how?

I think this article might answer that question. The presence of salt and other minerals with water can significantly lower the freezing point.

http://science.nasa.gov/headlines/y2000/ast29jun_1m.htm

This article will also shed some light as to how it is possible to have liquid water on Mars.

http://www.biospherics.com/mars/spie2/spie98.htm

thanks!

thank you very much marsmann.

I'm no geologist, but the recent surface sedimentation indicated on the opportunity rocks suggest that Mars had water recently (geologically speaking) and hence an atmosphere.

It is specualted that when the magma core cooled, the magnetic field could no longer repel the solar wind which stripped away the atmosphere and the water boiled off. Who know how long this took?

It is also possible that Mars geo-chemically absorbed the atmosphere and water. When the core cooled, the planet no longer vented gas to balance the absorption.

The rovers may add peices to your puzzle.

3man

The triple point for water is 6mb. The atmospheric pressure on Mars is greater than 6mb most of the time in the lowlands and as high as 13mb.

Thats how liquid water han exist on the surface at certian thermaly friendly times

Darwin

Darwin:

We have been looking at Hellas Crater on another thread, because it offers extra radiation protection. Also, it has some of the highest barometric pressures on Mars, because it is so deep. Have you looked into its weather?

It is about the size of the Western US.

Henry,

You may find this hard to believe, but yes.

Hellas is cloudy most of the time. This is due to cool air pooling and semi-permanent inversion. In the summer there is limited sunshine.

The forcast would go like this 70% of the time. My best guess.

Cloudy with a high around -30c low around -40c light winds.

Darwin

Images courtesy of Mizar.

Hellas Crater is the big dark blue circular blob.

So the daily high temperature at the Martian surface down inside Hellas is about –30 deg. C. I can see how the cloud cover would add to the radiation protection, but would that cloud cover make it warmer down inside, or colder?

I see that the top edge of Hellas runs up almost to the Equator, where the Sun is brightest. So I guess the best Martian real estate might be in Northern Hellas Crater.

yea i think you are right. the closer to the edge the more sunshine. we humans got to see a little sunshine now and then.

That looks like prime real estate.

Darwin

why so cold weatherman??

The mars farmers almanac, says they expect highs on the equator, up to 80f. or so.

Mars is a long ways away. Even on the equator when they say temps of 70f thats only a foot of the ground. if you go up 5 ft its 8f. Its not like earth. To the best of my knowlege

Darwin

Sorry guys i been in the bottle,

That may have been a little exstreem but not far off.

There is not a lot of atmosphere on Mars so you are not going to get that miami feeling on Mars.

But quit worriing about the temp. You are going to be in a suit that keps you warm and safe. Or you will be toast.

Darwin

Thgat 70 degrees near the surface is with max solar heat. Clouds just take away all the fun. But look on the bright side, it dont get to -123 at night

Mars being further from the sun than earth, perhaps lead to the faster cooling of the magma core than earth. As the Martian EMF reduced and atmosphere dissipated the lower atmospheric pressure would indeed simply "boil" the water away into space. Whereas the ionosphere and EMF of earth keep the water recycling within the earthzone. One geologist suggested that water on earth can be created from certain types of rock under geologic-tectonic pressures...he called this process virgin water. On a dead-dying planet...such fructifying tectonic forces would be absent. Also I just read that the nano particles (created via plates sliding against each other and other forces) help to seed clouds...the ionospheric "shield" of a planet it seems is intimately tied into a living, moving tectonic-volcanic planet...once the plasma cools and the EMF reduces, all the factors that keep the electromagnetic life system of a planet intact...slowly dissipate...leaving a dead lump of rock in space.

I have seen this information and lots more at http://newfileengine.com/
It is one of the best searches of the internet! very useful!

To preface this, I have not found scientific literature dealing with the best evidence relating to the formation of the Hellas crater.

Now, this is little more than a hunch of intuition, but it would seem to me that if the Hellas crater is an impact crater, a meteor that massive travelling at cometary speed should be more than enough to deliver the Joules required to blow off the majority of Mars's atmosphere.

If the Hellas crater is about 2300km in diameter, then we can roughly estimate that, as per [link] #hypervelocity we can conclude that our meteor has a mass of around 2.9*10^18 kg. That same website also provides the amount of energy required to blow off Earth's atmosphere entirely (note that Mars has less than 30% the surface area of Earth, and we're not aiming to blow all of the atmosphere off): 3.2*10^26 Joules. Plus all of this into our handy equation from Atomic Rockets, Ke = 0.5 * M * V², and we get... a meager velocity of 15km/s, which is just over 4 times less than the speed of Halley's Comet (70.56km/s).

With this huge margin for variation (asteroid mass can be much lower, velocity much higher, and energy required to blow off Mars' atmosphere much lower), I think it's plausible to propose that the meteor impact at Hellas Planitia blew off the atmosphere of Mars.

Link in that post should read:

http://members.tripod.com/reubs376_2001/meteorcrater.htm

I know it's not very scientific of my, but it's a good place to start. The meteor that caused it was 115km in diameter. As per [link]