Mars: no global mag field, no introduction of new atmo?

[bonzelite]

being that the core of mars is (allegedly) effectively "dead," as there is apparently no globally robust magnetic sphere to protect it's atmosphere from being stripped away by solar UV, how can any hope of reintroducing more atmosphere there be in any way effective? <br /><br />for example, there is methane at mars. we don't know why. but it is there. and the only way it can remain there is by replenishment. something is replenishing it. so how far can a replenishment cycle be effectively large enough before the scorching UV tears it away and keeps it at a permanent minimum level? or is there a minimum?

 

[mlorrey]

It isn't UV, it is the low gravity that is the problem. However, the rate of loss is so low that a concerted effort to create a viable human-tolerable atmosphere of 500 millibars would take tens of thousands of years to evaporate and precipitate again.<br /><br />One thing Mars lacks is sufficient radioactives in its core to maintain an active tectonic system. Mankind may eve be able to assist with this by dropping our high level nuclear waste into martian volcanic craters, until the wastepile reaches supercriticality and melts its way down to the core.

 

[JonClarke]

Several points.<br /><br />It's not just the low gravity, is also the solar wind that results in Mars losing it's atmosphere. Another factor is hat while Mars is cold it's not that cold. Titan has an even lower gravity, much is much colder, and experiences a far less intense solar wind, because of distance from the sun and the protection of saturns magnetic field.<br /><br />There is no evidence that Mars lacts radioactive elements.<br /><br />Dumping pradioactive wastes in craters until they "super critical" won't achieve anything but create a lot of radioactive debris that will spread round the planet. They certainly won't melt there way down to the core.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[mlorrey]

On the contrary, its low density and lack of tectonic activity speaks to a thick crust and mantle, and a very small core that is relatively cool, if not dead. This means a significant lack of radiactivity in the core. A supercritical mass would become molten and, because of its greater density, would rapidly sink and thermally bore its way through the crust. <br /><br />While some radioactivity will be emitted into the atmosphere initially, the resulatant lava will seal over the wound and total fallout will be on the order of Chernobyl. While such an event would be terrible on earth, the ambient radiation level that already exists on Mars is so high that the emitted fallout would disappear in the noise, and by the time man could walk around in shirtsleeves on the surface, the fallout would long since have degraded to earth-normal levels.

 

[JonClarke]

The low density is a function of the small size of Mars. Small size = less gravity = less compression = lower density. the smaller size also means that heat will be lost more rapidly and the planet cooled more effectively than earth. <br /><br />There is no evidence I am aware of that says that the bulk composition of mars is significanctly different from earth. But I will do some checking of this.<br /><br />The three main radioactive elements for heat production are uranium, thorium and potassium. The first two occur in such low abundances that they will have no measurable influence on bulk density. Potassium is more common but not a dense element, Potassium-rich minerals and rocks have low density, on average.<br /><br />Mars is not dead, the most recent lava flows are a few Ma in age. There is also geophysical evidence that the core is still liquid. What has changed is that the core no longer generates a global dynamo. <br /><br />The china syndrome is a myth. Any self sustaining fissioning mass of molten material would rapidly be diluted by material assimilated from the surrounds. It high get a few 100 m at most. You need to go thousands of km to reach the core. If it hit an aquifer or ground ice in the process you would get huge steam explosions.<br /><br />If your mass did get to the core (which it won't) it's mass will be isignificant compared to the mass of the core. <br /><br />I have many friends from Poland, Russia, and the Ukraine. they would regard a Chernobyl like event in far less blase terms that you. Yes, Mars is a high radiation environment. But there is a difference between cosmic radiation and contamination from radioactive particles. <br /><br />All this ignores the minor issue of transporting the thousands of tonnes of high level radiaoactive waste to Mars. One launch accident you will be running your experiment on earth. <br /><br />So this idea is notngoing to work. it's premise is wrong, it is completely impratcial and would have unaccep <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[bonzelite]

the responses are cool thus far. <br /><br />i never would have ever considered transporting nuclear material to mars, for example to help create a mag field. seems highly impractical and wouldn't work. <br /><br />nonetheless, perhaps in several centuries, terraforming may become seriously considered. if biomass is cultured and grown in millions of planetwide bubble city greenhouses, with the O2 waste of this mass being pumped into the air, would this perpetual replenishment be sufficient to thicken the air, or would it remain pathetically thin, as the air is now? the solar wind is extremely harsh without anything to buffer it's oncoming assualt. <br /><br />as well, i proposed the core to be ALLEGEDLY dead. the earth's moon, for example, experiences quakes and such, some believed to be simply from tidal forces of the earth, others attributed to tectonics, albeit minor. mars seems to have far more going for it than the moon. the martian core may be active, but not sufficiently so to generate a strong enough planetwide magnetosphere. <br /><br />yes? <br /><br />the dilemma is to ascertain whether mars can ever be a biogenetically viable world, seeded by the earth's myriad lifeforms and copius biomass. and this seems highly contingent on an atmosphere that is several orders of magnitude more robust and friendly than what exists right now. <br /><br />

 

[Saiph]

just as a nit-pick: <blockquote><font class="small">In reply to:</font><hr /><p>Small size = less gravity = less compression = lower density<p><hr /></p></p></blockquote><br /><br />Composition can play a large factor here. Afterall, Saturn has a density close to water's, ~4x less than any of the terrestrial planets.<br /><br />Ignoring composition, i'd agree wholeheartedly. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[jatslo]

There is a show about Mars on the History Channel right this minute.

 

[bonzelite]

good point. the anarctic as a mars analogue is the nearest laboratory for this premise. as long as the bacteria were enshured protection from the runaway UV of mars, they would probably thrive. they'd metabolize the extant martian CO2 with the H2O ice and give off O2. this is how it is commonly believed the earth acquired it's atmospheric O2 --during the rise and fall of myriad ice ages, these bacteria proliferated. and mars has this environmental condition already going for it, as it is permanently frozen. and apparently with copius amounts of subsurface ice sheets; probably more than we think at this point. <br /><br />a long shot, too, is O3, ozone, could evolve from this process given enough millions of years of successful seeding. the question is would the relative absence of a magnetosphere dash hopes for this hypothesis?<br />

 

[yevaud]

Well, short answer is yes and no.<br /><br />The point about mass=gravity is in part that a planet's ability to retain atmosphere is due to how easily (or not) said atmospheric species may escape. In the case of Mars, it's lower gravity lowers the atmospheric escape velocity for species, making it far easier to lose it.<br /><br />Next, the absence of a strong geomagnetic field means that there is nothing there as well to prevent said species being swept away by the solar wind.<br /><br />A further side issue is the relatively "dead" core of Mars. An active core would mean an increase in general outgassing, which is one serious mechanism for replenishing lost atmosphere. This process is occurring here, on Earth, even as we speak.<br /><br />So, on the one hand, yes, it would be an impediment. <br /><br />Then again, it all depends. If, for example, Mars' surface was repeatedly bombarded by icy material from orbit, I think atmospheric pressure could be markedly increased. Of course, it would also escape much faster than here, but - this is the caveat - how fast? It could be that we could, through a variety of means, increase the atmospheric pressure of Mars to 1/2 that of Earth. It may well take millions of years to significantly lose it again.<br /><br />Just a few thoughts and idle speculations. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>