Why is it always Mars?

[JohnB]

Why do we always talk about colonizing Mars? Why not Venus?

 

Mars is a little dirtball of a planet with bugger all atmosphere (except at Jullagg's Bar on a Saturday night ). What it does have is 98% CO2. It has low gravity and no water to boot, generally a nothing planet.

 

Venus OTOH has a good thick atmosphere, is a better size and there seems to be a lot of water in the clouds. Yes, it's harder to get to, is bloody hot and has phenomenal storms due to the runaway greenhouse effect.

 

But I've always wondered what would happen if we dumped 100 tons or so of nice photosynthetic bacteria into the atmosphere and waited. The CO2 gets converted, the greenhouse breaks, temperature drops and the water falls as rain. Sulphuric acid rain granted but something could be done about that.

 

There would be great difficulties Terraforming either planet but it just seems easier to convert an already existing atmosphere into something useful rather than trying to create one from scratch.

 

So, why is it always Mars?

[the tree]

It isn't always Mars, living on Venus would quite possibly mean living in a giant blimp.

 

http://en.wikipedia.org/wiki/Colonization_of_Venus

[insane_alien]

mars is also easier to get back from.it has reasonably low gravity and a thin atmosphere. that means you only need a small rocket to get back. venus in the other hand isn't even possible. the rockets wouldn't provide much thrust and youd need a damn lot of them to get through the atmosphere(this is ignoring how you're going to get the rocket there in the first place and fuel it in 400*C temperatures.

[ecoli]

There's also plenty of volcanoes we'd have to deal with.

[Pangloss]

Well just to get back to the spirit of the OP, why does Mars seem to have more colonization appeal than the Moon? All of the reasons I've seen stated above for preferring Mars over Venus would seem to apply to an even greater degree when it comes to the Moon, and yet it would seem to be a far less popular idea than colonizing Mars. Is it just a matter of romantic appeal?

[MolotovCocktail]

That is something I have always wondered myself. For one, the moons of our solar system seem much more habitable than Mars, especially Jupiter's and Saturn's. And our own moon has a huge amount of titanium and other metal resources. Also, why not comets and astroids, they have organic material, water, and useful resources.

 

<edit> I think the reason for the popularity of Mars is probably because a lot of people believe that it was Earth-like in the past and the fact that it is the planet that popular science likes to talk about.

[ecoli]

perhaps because the moon doesn't have an atmosphere at all?

[MolotovCocktail]

perhaps because the moon doesn't have an atmosphere at all?

 

Yeah, but we can't breathe on Mars either.

[Sisyphus]

Mars is still a lot more "Earth-like" than the moon, inasmuch as it has more gravity and an actual atmosphere. It also has a lot of water, albeit mostly trapped in the polar ice caps. However, there is a small amount of water vapor in the atmosphere, and the surface is at least relatively close to the temperature range for liquid water. For these and other reasons it would almost certainly be by far the easiest to terraform. It has its own problems, obviously, but none quite as severe as the problems of, say, Venus, or Jupiter's moons.

[Pangloss]

perhaps because the moon doesn't have an atmosphere at all?

 

Actually I believe the moon does have a gravitationally-bound atmosphere. It's just a really trivial one. But then the same could be said about Mars. Does the Martian atmosphere have any practical value for potential settlers at all? Surely teraforming is a distant dream, and we can probably ship water to the moon faster than you can pull it out of the Martian atmosphere. (But maybe not cheaper.) The point about gravity might have some merit.

 

There is, of course, something to be said about the aerobraking value of the Martian atmosphere (the Moon's is too thin for such, I assume). But then you don't really need a braking effect for lunar landing, since you can get there at a relatively low velocity (in a quite reasonable amount of time).

[Sisyphus]

It seems like there has to be value in an atmosphere, doesn't there? It would act as a meteor shield, at least. It would also moderate the temperature some, so you wouldn't get the extremes of the moon. Maybe it would also make airtightness less an immediate problem of life and death because leaks would be slower (and the atmosphere is non-toxic, albeit oxygenless). It has extremely high winds, which might be useful for power (or maybe not, what with the really low pressure). An atmosphere also leaves open the possibility of airborne vehicles, whereas on the moon you'd have to use either ground vehicles or rockets to get around. Again, though, feasibility is questionable because of pressure.

[Pangloss]

Interesting point about meteor shields. Could that point possibly be offset by setting up a lunar colony on the side of the moon that faces the Earth? I know the near side can still be hit, but I believe the odds are far lower, right?

 

Another interesting point about air pressure. Sealing out a toxic atmosphere is probably less of an engineering challenge than sealing in an atmosphere against a virtual vacuum. I guess the question there would be whether the difference is worth the lifting/transport cost.

[JohnB]

Mars is certainly easier from the POV of early exploration. When I spoke of colonization I was thinking in the long, very long, term. People being able to live outdoors, terraforming.

 

Any Martian atmosphere we create, the planet will lose because of the low gravity, so we will have to keep replentishing it. For that matter, where are we going to get enough gas to make a breathable atmosphere in the first place?

 

That's why I've wondered about Venus, at least there's something to work with. Once the greenhouse is broken, the temperature would come down and the planet would approach more "Earth like" conditions.

 

I suppose the question is "What would be the mean surface temperature on Venus if the greenhouse was broken?" Perhaps the temperature wouldn't drop far enough for liquid water to form. Unless you could cool the planet further, it would be useless as a colonization target.

 

In the short term though, I'd like to see a 10,000 person self sustaining colony on the Moon.

[Pangloss]

Actually I'm not sure about that bit regarding losing atmosphere to low gravity. I think it's generally believed that it once had a much thicker atmosphere, but lost it due to the fact that it lost its electromagnetic field. (Earth's atmosphere would be washed away too, in spite of its higher gravitic field, were it not for the electromagnetic shock wave that proceeds it in its orbital push against solar wind.)

 

I'm just dimly recalling this, so someone please correct me if I'm wrong.

[Sayonara]

Unless you could cool the planet further, it would be useless as a colonization target.

 

In the short term though, I'd like to see a 10,000 person self sustaining colony on the Moon.

 

Read the link in the first reply about the colonisation of Venus - it is actually fairly ideal for atmospheric habitation.

 

 

Actually I'm not sure about that bit regarding losing atmosphere to low gravity. I think it's generally believed that it once had a much thicker atmosphere, but lost it due to the fact that it lost its electromagnetic field. (Earth's atmosphere would be washed away too, in spite of its higher gravitic field, were it not for the electromagnetic shock wave that proceeds it in its orbital push against solar wind.)

 

I'm just dimly recalling this, so someone please correct me if I'm wrong.

 

Yes, you are quite right. The magnetic field basically deflects the solar wind, which would otherwise tear away the atmosphere.

 

Makes you wonder what Mars was like before... that could be our fate one day

[Pangloss]

Which really makes terraforming a lot more complex, doesn't it? You can build it up but it'll just get whisked away again. Though I suppose if you have the technology to build it up then you probably have the technology to overcome the leakage.

[Sayonara]

Given enough resources we could deploy some kind of web-like field generator in orbit, but I suspect that even a massively powerful EM "shield" would probably only slow the loss down. Constantly pumping out Mars-brand atmosphere might actually be cheaper.

[Genecks]

Earthlings simply want to boot us off our planet. Your governments have always used distracting/confusing/strawman ways to make people do something. We don't really like it.

[MolotovCocktail]

Given enough resources we could deploy some kind of web-like field generator in orbit, but I suspect that even a massively powerful EM "shield" would probably only slow the loss down. Constantly pumping out Mars-brand atmosphere might actually be cheaper.

 

Well, the strength of Earth's magnetic field is only about .6 Gauss (Source: http://209.85.165.104/search?q=cache:ufQf0O6RRGUJ:science.nasa.gov/newhome/headlines/ast20may98_1.htm+How+strong+is+Earth%27s+Magnetic+Field&hl=en&ct=clnk&cd=2&gl=us), and MRI scanners can generate magnetic fields thousands of times stronger than that. The hard part would be putting it around an entire planet.

 

I would have to say that Sayonara's suggestion about pumping Mars brand atmosphere to be best, and probably much easier to do.

[Sisyphus]

Would you even need to shield it? I mean, there would be leakage, of course, but how much? If it would take 2 million years for Mars to lose its atmosphere again, then who really cares? It can be built up faster than its lost.

 

Another interesting point about air pressure. Sealing out a toxic atmosphere is probably less of an engineering challenge than sealing in an atmosphere against a virtual vacuum.

 

That's what I was thinking. Isn't the Martian atmosphere non-toxic, though? It's almost all CO2, right? You couldn't breathe it, but I doubt it would matter if it mixed with habitat air as long as you maintained the O2 levels.

[richard]

Using plants to use the co2 and make oxygen would be easy enough if we find frozen water. Then if possible large orbiting mirrors to reflect a bit more light/heat down and deflect some direct radiation. Tis a nice idea. I would like to see something like this in my life time. Come on NASA, you got while next Tuesday.

[Sayonara]

Isn't the Martian atmosphere non-toxic, though? It's almost all CO2, right? You couldn't breathe it, but I doubt it would matter if it mixed with habitat air as long as you maintained the O2 levels.

 

Carbon dioxide is dangerously toxic at levels as low as 5% by volume, so although it is not a massive risk you would definitely need constant monitoring and compensation.

 

Oh, you also need to take into account that tolerance to gaseous toxins like carbon dioxide will be reduced in Mars colonists due to the physiological effects of the low gravity.

[Ophiolite]

Carbon dioxide is dangerously toxic at levels as low as 5% by volume,

The implications of this statement are patent nonsense, perhaps because the statement was poorly thought through. Carbon dioxide is dangerously toxic at levels of 5% by volume at standard Earth atmospheric pressure.

The toxicity is determined by the partial pressure of the gas and at Mars standard atmospheric pressure we have only (back of the envelope calculation) the equivalent of less than 1% by volume.

In any case the whole argument is irrelevant since there ain't any oxygen to breathe and the partial pressure, even if the entire Martian atmosphere was oxygen, would be too low to force it into the bloodstream.

So I'm left wondering what the hell you are all warbling about.

[Sayonara]

The implications of this statement are patent nonsense, perhaps because the statement was poorly thought through. Carbon dioxide is dangerously toxic at levels of 5% by volume at standard Earth atmospheric pressure.

The toxicity is determined by the partial pressure of the gas and at Mars standard atmospheric pressure we have only (back of the envelope calculation) the equivalent of less than 1% by volume.

In any case the whole argument is irrelevant since there ain't any oxygen to breathe and the partial pressure, even if the entire Martian atmosphere was oxygen, would be too low to force it into the bloodstream.

So I'm left wondering what the hell you are all warbling about.

What I am warbling on about, Ophiolite, is a controlled human-breathable atmosphere in Sisyphus's and Pangloss's "Martian atmosphere sealed out" habitat (see posts #12 and #20), which would in all likelihood be maintained at or about one standard Earth atmosphere.

 

So before your next leap to the reply box, I suggest you take more time to actually follow the discussion, and less time thinking about how to be condescending and downright rude.

[MolotovCocktail]

Another thing I've been wondering is that if we are going to pump gases into the atmosphere to increase pressure, how do we go about reducing radiation levels on the planet? We could probably pump out ozone in order to block out the UV rays but what do we do to protect the planet from being bombarded by gamma and cosmic rays from space. On Earth, we have a magnetic field protecting us from such radiation, but there is no such magnetic field on Mars. Even if we did find a way to make the Martian atmosphere similar to Earth's, you still need to find a way to block out harmful radiation to make it as habitable as Earth, otherwise it would still be devoid of life and hostile for humans.