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It also has a type of natural disaster that we don’t have: solar flares. Mars has no dynamo within its core the way Earth does. Mars therefore has a much weaker

It also has a type of natural disaster that we don’t have: solar flares. Mars has no dynamo within its core the way Earth does. Mars therefore has a much weaker magnetic field and so is far more susceptible to charged particles from the sun. Solar flares present a huge problem for people living on Mars unless they’re underground. They destroy any technology that isn’t well-shielded. They also represent a major obstacle to a project to terraform Mars because the charged particles will strip away the atmosphere you’re trying to build.

EGreg 6y ago
How do they strip it away though
- deleted 6y ago
  [deleted]
- bhickey 6y ago
  The solar wind hits molecules in the atmosphere and knocks them into space. This is how Venus lost most of its hydrogen. https://www.nasa.gov/press-release/nasa-mission-reveals-speed-of-solar-wind-stripping-martian-atmosphere https://www.nasa.gov/press-release/nasa-mission-reveals-spee...
  - wahern 6y ago
    A prerequisite was that Venus lost its solid and liquid water. As the temperature rose water couldn't precipitate, leaving it all exposed in the upper atmosphere. Oxygen and hydrogen would photo-dissociate and the lower mass hydrogen would get kicked out into space at a higher rate. I don't think you need solar wind-magnitude energies for Venus to have lost it's hydrogen, it just sped up the process. Venus is pretty big, but it's also really hot. Venus' gravity to temperature ratio permit significant amounts of free hydrogen to be lost thermally without any solar wind sweeping it away. I think it's possible that Venus lost most of its hydrogen to thermal escape, particularly hydrodynamic escape, though today it's no longer the predominate mechanism for what little hydrogen remains.
    - EGreg 6y ago
      Are you saying thermal escape can speed up molecules to such a speed that gravity can't get them back down and they just escape into space?
      - wahern 6y ago
        Yes, not just hydrogen but even heavier atoms and molecules. See https://en.wikipedia.org/wiki/Atmospheric_escape#Thermal_escape_mechanisms https://en.wikipedia.org/wiki/Atmospheric_escape#Thermal_esc... The Wikipedia article (https://en.wikipedia.org/wiki/Hydrodynamic_escape https://en.wikipedia.org/wiki/Hydrodynamic_escape) on hydrodynamic escape talks about escaping heavy molecules as if that's the principle function of the mechanism. But in much of the scientific literature on early Venus, hydrodynamic escape seems to refer primarily to the escape of free hydrogen.[1] I'm not a scientist so I don't know what to make of that, but in any event thermal mechanisms (i.e. Jeans and hydrodynamic) can absolutely cause gaseous particles to reach escape velocity. [1] Photodissociation splits H2O, hydrogen is kicked out into space via thermal mechanisms, and much of the remaining oxygen, too heavy to escape at a significant rate under the local parameters, is sequestered by the molten core, volcanism, and surface weathering. At least, that's how I understand the literature as a layman. The modern debates and research seem to be centered around the particularities, especially the early geology, such as how long core material was exposed.
gpm 6y ago
Solar radiation and flares are worth mentioning, but are easily solved by the "hide underground" or "hide under water tanks" solutions. > They also represent a major obstacle to a project to terraform Mars because the charged particles will strip away the atmosphere you’re trying to build. Not at a rate fast enough to matter, it's negligible on human timescales.
kemiller 6y ago
Right so most plans call for living underground, at least until they can put some kind of shielding device at a Lagrange point. I assume that’s what really drives Elon’s interest in the boring company.
lumost 6y ago
A mars colony would likely need to be underground from the get go. Much lower risk of catastrophic air leakage + cheap radiation shielding.
- mikepurvis 6y ago
  But going underground here on Earth also insulates you from like 99% of planet-scale disaster scenarios, especially if you're growing your crops underground and recirculating your breathing air, both of which you'd be doing in a Mars underground settlement. I'm totally down for how nifty it would be to have off-world colonies, but trying to sell it to the public with these "what if" arguments doesn't even begin to pass the sniff test. Gates has been sounding the alarm for years about viral pandemics and basically nothing was prepared for it; how capable would we be of spending trillions on a "backup Earth" when we can't even spend a few million a year on stockpiling medical PPE?
  - lumost 6y ago
    fully agree - but there is a middle ground. Antarctica has maintained permanent year round settlements for various purposes over the last century. These settlements exist for no other reason than there are both scientific and economic resources unique to Antarctica. Barring a general change in the habitability of the Moon/Mars or other astronomical body I'd wager that you would have a similar dynamic. If unique economic purposes are discovered including rich surface deposits, low-G fuel generation, or lower environmental concerns then the population in these settlements would grow for the same reasons that people have always moved to the frontier.
    - LargoLasskhyfv 6y ago
      Which economic resources? I always thought research settlements are a money sink. Or are you speaking of the little bit of tourism?
      - lumost 6y ago
        Research settlements are funky, funding agencies and scientists would be quite interested in understanding the geology dynamics on a tectonically dead world. Biologists will want to understand why mars never developed life. Medical researchers will want to understand the effects of isolation, and low-g. Donors, and funding agencies interested in these fields will want to fund expeditions. The expeditions will need infrastructure. The infrastructure's existence will motivate a few entrepreneurial expeditions. Once the transit economics are understood, The Moon and Mars can both provide accessible surface deposits of water, iron, copper, and other commodities to orbit for less energy than earth. A number of activities for resource procurement for commercial space industries will be a tad easier when attached to a big low-g rock where an extra green house can simply be dug out. The relative lack of environmental externalities from mining and other activities may be a resource unto itself in the next few decades. On a longer timeline - Mars could be given a tolerable atmospheric pressure and liquid water for <100 trillion dollars. Barring a change in global growth rates that would be ~3% of annual global GDP by 2120, and .1% by 2220.

EGreg 6y ago

How do they strip it away though

deleted 6y ago
[deleted]
bhickey 6y ago
The solar wind hits molecules in the atmosphere and knocks them into space. This is how Venus lost most of its hydrogen. https://www.nasa.gov/press-release/nasa-mission-reveals-speed-of-solar-wind-stripping-martian-atmosphere https://www.nasa.gov/press-release/nasa-mission-reveals-spee...
- wahern 6y ago
  A prerequisite was that Venus lost its solid and liquid water. As the temperature rose water couldn't precipitate, leaving it all exposed in the upper atmosphere. Oxygen and hydrogen would photo-dissociate and the lower mass hydrogen would get kicked out into space at a higher rate. I don't think you need solar wind-magnitude energies for Venus to have lost it's hydrogen, it just sped up the process. Venus is pretty big, but it's also really hot. Venus' gravity to temperature ratio permit significant amounts of free hydrogen to be lost thermally without any solar wind sweeping it away. I think it's possible that Venus lost most of its hydrogen to thermal escape, particularly hydrodynamic escape, though today it's no longer the predominate mechanism for what little hydrogen remains.
  - EGreg 6y ago
    Are you saying thermal escape can speed up molecules to such a speed that gravity can't get them back down and they just escape into space?
    - wahern 6y ago
      Yes, not just hydrogen but even heavier atoms and molecules. See https://en.wikipedia.org/wiki/Atmospheric_escape#Thermal_escape_mechanisms https://en.wikipedia.org/wiki/Atmospheric_escape#Thermal_esc... The Wikipedia article (https://en.wikipedia.org/wiki/Hydrodynamic_escape https://en.wikipedia.org/wiki/Hydrodynamic_escape) on hydrodynamic escape talks about escaping heavy molecules as if that's the principle function of the mechanism. But in much of the scientific literature on early Venus, hydrodynamic escape seems to refer primarily to the escape of free hydrogen.[1] I'm not a scientist so I don't know what to make of that, but in any event thermal mechanisms (i.e. Jeans and hydrodynamic) can absolutely cause gaseous particles to reach escape velocity. [1] Photodissociation splits H2O, hydrogen is kicked out into space via thermal mechanisms, and much of the remaining oxygen, too heavy to escape at a significant rate under the local parameters, is sequestered by the molten core, volcanism, and surface weathering. At least, that's how I understand the literature as a layman. The modern debates and research seem to be centered around the particularities, especially the early geology, such as how long core material was exposed.

gpm 6y ago

Solar radiation and flares are worth mentioning, but are easily solved by the "hide underground" or "hide under water tanks" solutions. > They also represent a major obstacle to a project to terraform Mars because the charged particles will strip away the atmosphere you’re trying to build. Not at a rate fast enough to matter, it's negligible on human timescales.

kemiller 6y ago

Right so most plans call for living underground, at least until they can put some kind of shielding device at a Lagrange point. I assume that’s what really drives Elon’s interest in the boring company.

lumost 6y ago

A mars colony would likely need to be underground from the get go. Much lower risk of catastrophic air leakage + cheap radiation shielding.

mikepurvis 6y ago
But going underground here on Earth also insulates you from like 99% of planet-scale disaster scenarios, especially if you're growing your crops underground and recirculating your breathing air, both of which you'd be doing in a Mars underground settlement. I'm totally down for how nifty it would be to have off-world colonies, but trying to sell it to the public with these "what if" arguments doesn't even begin to pass the sniff test. Gates has been sounding the alarm for years about viral pandemics and basically nothing was prepared for it; how capable would we be of spending trillions on a "backup Earth" when we can't even spend a few million a year on stockpiling medical PPE?
- lumost 6y ago
  fully agree - but there is a middle ground. Antarctica has maintained permanent year round settlements for various purposes over the last century. These settlements exist for no other reason than there are both scientific and economic resources unique to Antarctica. Barring a general change in the habitability of the Moon/Mars or other astronomical body I'd wager that you would have a similar dynamic. If unique economic purposes are discovered including rich surface deposits, low-G fuel generation, or lower environmental concerns then the population in these settlements would grow for the same reasons that people have always moved to the frontier.
  - LargoLasskhyfv 6y ago
    Which economic resources? I always thought research settlements are a money sink. Or are you speaking of the little bit of tourism?
    - lumost 6y ago
      Research settlements are funky, funding agencies and scientists would be quite interested in understanding the geology dynamics on a tectonically dead world. Biologists will want to understand why mars never developed life. Medical researchers will want to understand the effects of isolation, and low-g. Donors, and funding agencies interested in these fields will want to fund expeditions. The expeditions will need infrastructure. The infrastructure's existence will motivate a few entrepreneurial expeditions. Once the transit economics are understood, The Moon and Mars can both provide accessible surface deposits of water, iron, copper, and other commodities to orbit for less energy than earth. A number of activities for resource procurement for commercial space industries will be a tad easier when attached to a big low-g rock where an extra green house can simply be dug out. The relative lack of environmental externalities from mining and other activities may be a resource unto itself in the next few decades. On a longer timeline - Mars could be given a tolerable atmospheric pressure and liquid water for <100 trillion dollars. Barring a change in global growth rates that would be ~3% of annual global GDP by 2120, and .1% by 2220.