Why colonize Mars and not the Moon?

[ProfChuck]

No, it does not. Escape rate is very, very, very low on human life timescale.

Atmospheric retention is a long term problem. Atmospheric surface pressure in a 1/3 g environment is another. Pressure suits and portable oxygen will be required for a long time. You might want to take a look at this http://onlinelibrary.wiley.com/doi/10.1002/jgre.20164/abstract

 

[mfb]

Atmospheric surface pressure in a 1/3 g environment is another.

1/3 g just means you need a factor 3 more gas for the same surface pressure and area. As the surface area of Mars is smaller by a factor ~4, you actually need less gas than on Earth for the same surface pressure.

You still need a huge amount of oxygen in the atmosphere to make it breathable (and a huge amount of anything to have a small gas mask work), but 1/3 g doesn't make it impossible.

 

[ProfChuck]

1/3 g just means you need a factor 3 more gas for the same surface pressure and area. As the surface area of Mars is smaller by a factor ~4, you actually need less gas than on Earth for the same surface pressure.

You still need a huge amount of oxygen in the atmosphere to make it breathable (and a huge amount of anything to have a small gas mask work), but 1/3 g doesn't make it impossible.

I agree. I never said it was impossible, just very hard. There is a series of serious engineering challenges but because the problem can be reduced to numbers it is doable. The Martian atmosphere is over 90 percent carbon dioxide so there is plenty of oxygen if it can be separated from the carbon. When I was at JPL we looked at the problem. It turns out that one approach would be the development of a hybrid photosynthetic plant that would survive in the cold low pressure environment. Most vegetation is voraciously opportunistic when it comes to extracting carbon dioxide which is actually plant food. It does require water but there are indications that it exists in large quantities tied up in the soil and perhaps in frozen aquafirs. So reducing CO2, releasing O2 and providing food could be a win-win-win situation. However, this kind of vegetation tends to be very aggressive so control methods and strategies must be in place. It is an interesting problem.

 

[Frosted Flake]

Air.

Mars has some, the Moon has none. If you are going to try to make something, it's good to have something to work with. Where would Dillinger be without that bar of soap?

 

[mfb]

The Martian atmosphere is over 90 percent carbon dioxide so there is plenty of oxygen if it can be separated from the carbon.

Not enough to make a breathable atmosphere. In addition, converting CO2 to oxygen and bound carbon would make Mars even colder. We would first have to free the CO2 in the ice caps or find another large CO2 source.

NASA's Mars 2020 rover will have an experiment to generate O2 from the atmosphere. With the idea to use such a system for a future closed habitat, not with the idea of releasing it into the atmosphere.

 

[ProfChuck]

I agree. Turning Mars into a "shirt sleeve" environment is beyond any current or potential technology. I suspect that a big seller in the future will be a comfortable light weight environment suit that will permit "outdoors" activity with maximum mobility and minimum restrictions.

 

[Frosted Flake]

Turning Mars into a "shirt sleeve" environment is beyond any current or potential technology.

Strike that word 'potential'. We are fairly clever apes. We just might invent something.

 

[ProfChuck]

You are quite right. Some clever person may well see a solution that evades the rest of us. At least I hope so. It has happened many times in the past.

 

[1oldman2]

This is a "Fun read"
From, https://fivethirtyeight.com/features/mars-needs-lawyers/
"We may slip the surly bonds of Earth, but we will not escape the knots tied by Earth law and politics.

These issues are further complicated by the fact that they overlap with stated priorities of the current U.S. president in complex (and probably, at this point, unpredictable) ways."

 

[Al_]

Mars colonies are easier but still difficult.

I don't think this can be assumed. There are a number of strong counter-arguments in this thread.

I suspect that a big seller in the future will be a comfortable light weight environment suit that will permit "outdoors" activity with maximum mobility and minimum restrictions.

- and such a suit would have to be a vacuum suit. Which would enable it to be used on the Moon...

We seem to have slipped into terraforming discussions again. This thread is about colonisation, which is a much more immediate possibility.

 

[Buzz Bloom]

What extinction event on Earth could possibly make life on Earth less tenable than life on Mars or the Moon?

WW III

 

[mfb]

- and such a suit would have to be a vacuum suit. Which would enable it to be used on the Moon...

Moon has stronger requirements for thermal regulation and potentially more abrasive dust.

 

[ProfChuck]

I don't think this can be assumed. There are a number of strong counter-arguments in this thread.- and such a suit would have to be a vacuum suit. Which would enable it to be used on the Moon...

We seem to have slipped into terraforming discussions again. This thread is about colonisation, which is a much more immediate possibility.

If we expect to have anything more than a sparse outpost some degree of teraforming will be necessary. It may also include a bit of "Marsforming" of the settlers.

 

[Al_]

If we expect to have anything more than a sparse outpost some degree of teraforming will be necessary.

How so? Surely the effort and expense of creating or transporting HUGE amounts of gas is a very great deal more than the effort of creating large, luxurious indoor spaces?

Moon has stronger requirements for thermal regulation and potentially more abrasive dust.

True, but if we know how to build a light, comfortable space suit, these other problems are relatively easy to solve.

Mars has a much richer geology (areology?). It had liquid water in the past, where we can still study the indicators of it. It has wind reshaping the landscape, it has water/ice mixtures changing the landscape today (->RSL). It is larger as well.

All true. But I bet the Moon has some great sights to see too. And some great science to do. This is not a good reason to ignore the Moon as a site for the first space colony, given it's much greater accessibility, etc.

 

[PeroK]

WW III

And then we are back to the argument that it is impossible to build a secure bunker on Earth, but, somehow, we can build one on Mars.

This is an argument I don't even begin to understand.

 

[Buzz Bloom]

This is an argument I don't even begin to understand.

Hi @PeroK:

Conceptually what would be built on Mars is not a bunker. As I understand the meaning of "bunker", it is a temporary place of survival.

A definition.

A protective embankment or dugout; especially : a fortified chamber mostly below ground often built of reinforced concrete and provided with embrasures.
https://www.merriam-webster.com/dictionary/bunker​

There are likely to be many different interpretations of what a human presence on Mars might be, but it seems to me to be most likely that it would be (or become) a self sufficient colony that can exist indefinitely without needing further resources from Earth. There are also diverse opinions about (1) how extreme the damage on the surface might be, and (2) the length of time people surviving WW III in a bunker would need to stay there before the conditions on the surface of the planet can again sustain life.

Regards,
Buzz

 

[PeroK]

Hi @PeroK:There are also diverse opinions about (1) how extreme the damage on the surface might be, and (2) the length of time people surviving WW III in a bunker would need to stay there before the conditions on the surface of the planet can again sustain life.

Regards,
Buzz

Mars can't sustain life at all. That's the point. Something catastrophic happens on Earth which makes life unsustainable, so we live on Mars, where life is ... totally and utterly unsustainable in the first place.

Yes, I know, you'll have all the technology on Mars to build, make, grow whatever you need. And, that technology - for reasons I fail to grasp - cannot be deployed on Earth.

 

[sophiecentaur]

Mars can't sustain life at all. That's the point. Something catastrophic happens on Earth which makes life unsustainable, so we live on Mars, where life is ... totally and utterly unsustainable in the first place.

Yes, I know, you'll have all the technology on Mars to build, make, grow whatever you need. And, that technology - for reasons I fail to grasp - cannot be deployed on Earth.

I agree with most of that. It strikes me that the proponents of colonising other planets are a bit like people who would rather get on board a life raft than stay and take their chances on a yacht that isn't yet sinking. Life would be absolute hell for the first hundreds of years at least and I really doubt that the people of Earth would fund this project on anything more than a low priority and very long term basis.
Space and other planets are not the slightest bit like the Wild Frontier. There is absolutely no historical precedent for colonising planets.

 

[Buzz Bloom]

Yes, I know, you'll have all the technology on Mars to build, make, grow whatever you need. And, that technology - for reasons I fail to grasp - cannot be deployed on Earth.

Hi @PeroK:

Hypothetically, WW III might make the surface of the Earth radioactive for millennia. Another scenario is that the atmosphere becomes filled with small particles that block sunlight, perhaps for centuries. Trying to reestablish a productive way to grow food might not be possible.

On Mars, even though sunlight is much weaker than on Earth, satellite mirrors in stationary orbits could amplify the sunlight over areas where crops might grow.

Regards,
Buzz

 

[rootone]

Even though a nuclear war would be disaster for humans and much of other life on Earth, a lot of the radioactive fallout would be short lived. It would also not be at lethal levels all over the planet, mostly it would be near where large populations and military bases had been. Bombing places like Greenland or Australia would be a waste of a valuable bomb.
After the war, which would probably be all over in a few days, the um *cough* 'winner' could establish small clean zones, even if they have to start underground with artificial lighting, then grow from there.
Nasty as that prospect may be, it still is likely easier to restore a broken Earth biosphere than to create one from nothing on Mars.
Mars as a home for humans after we trash the Earth, is in my opinion not a very positive way to think about the future.

 

[mfb]

Artificial lighting is a major issue. If we go by total power humans use in some way, sunlight to grow plants wins by a huge margin. It rarely appears in statistics because it is free. It is free on Mars as well, and even similar to the conditions on Earth: The solar constant is just half, but on average the atmosphere absorbs less light than on Earth.
Sunlight on Earth after a massive nuclear war would be problematic for many years, you would need a massive power source to grow food. Possible, but not easy.

 

[Vikas Tyagi]

Life on Moon can't be possible because there is no atmosphere on moon to block ultraviolet rays emitted by sun. On the other hand, life on Mars can't be possible because of its much lower temp.

 

[PeroK]

Hi @PeroK:

Hypothetically, WW III might make the surface of the Earth radioactive for millennia. Another scenario is that the atmosphere becomes filled with small particles that block sunlight, perhaps for centuries. Trying to reestablish a productive way to grow food might not be possible.

On Mars, even though sunlight is much weaker than on Earth, satellite mirrors in stationary orbits could amplify the sunlight over areas where crops might grow.

Regards,
Buzz

Your argument could be characterised as:

a) We have a serious problem on Earth. No sunlight. To which there can't possibly be a solution.

b) But, we could live on Mars because we can develop all the technology we need there.

In other words, when considering the results of a cataclysm on Earth, we are constrained by science fact. But, when considering life on Mars we are unconstrained and are free to imagine whatever technology we need.

 

[sophiecentaur]

Nasty as that prospect may be, it still is likely easier to restore a broken Earth biosphere

Earth is about as 'goldilocks' place as you could think of, so it would be very well suited to re-terraforming. Moreover, many more people would benefit from the exercise than the few that could be transported to Mars or wherever.

 

[Buzz Bloom]

Mars as a home for humans after we trash the Earth, is in my opinion not a very positive way to think about the future.

Hi @rootone:

Among the various attitudes and thoughts regarding this topic, there are optimists and pessimists.

Regards,
Buzz

 

[Dale]

This is a "Fun read"
From, https://fivethirtyeight.com/features/mars-needs-lawyers/
"We may slip the surly bonds of Earth, but we will not escape the knots tied by Earth law and politics.

These issues are further complicated by the fact that they overlap with stated priorities of the current U.S. president in complex (and probably, at this point, unpredictable) ways."

Looks like FiveThirtyEight is having a Mars month. Here is another good article.

https://fivethirtyeight.com/features/all-we-really-need-to-get-to-mars-is-a-boatload-of-cash/

 

[Buzz Bloom]

We have a serious problem on Earth. No sunlight. To which there can't possibly be a solution.

Hi @PeroK:

I do not know what others with technical skills will be able to come up with to deal with dust that shuts out sunlight. I am not able to think of any solution, nor have I ever read any solution ideas from anyone else.

Regards,
Buzz

 

[Dale]

Would it be easier to colonize artificial habitats in space instead of either Mars or the Moon? I have always see the discussion as "either Mars or Moon", but not including permanently inhabited space stations. Is there a reason?

 

[PeroK]

Hi @PeroK:

I do not know what others with technical skills will be able to come up with to deal with dust that shuts out sunlight. I am not able to think of any solution, nor have I ever read any solution ideas from anyone else.

Regards,
Buzz

You could live on tinned food! Use artificial light and heat.

 

[Buzz Bloom]

You could live on tinned food! Use artificial light and heat.

Hi @PeroK:

For what period of time and for how many people do you think it would be possible to store food in a bunker? Also, how much and what would be the energy source for light and heat? For what period of time would the stored energy source last?

Regards,
Buzz