Why colonize Mars and not the Moon?

[lifeonmercury]

Since the surface gravity on Mars is only 38% that of Earth's surface gravity, I imagine the people living on Mars would be much weaker than those who remain on Earth.

 

[rootone]

Since the surface gravity on Mars is only 38% that of Earth's surface gravity, I imagine the people living on Mars would be much weaker than those who remain on Earth.

That isn't in itself a problem - while they are on Mars - since less gravity means less effort is required to get some things done.
However, we don't know whether people adapted to Mars's gravity would be able to re-adapt to Earth.
What we do know is that long-term astronauts on the ISS lose body mass despite doing frequent exercise.
Recovery can take a year or more, and for some individuals there can be irreversible physiological change, (though not to the extent of rendering them disabled)

 

[houlahound]

Why choose from big rocks in space when floating space stations are already proven and are more feasible.

 

[Algr]

Space stations tend to be lacking in raw materials.

 

[houlahound]

Space stations tend to be lacking in raw materials.

Food you can grow, energy you can harvest other stuff you could mine from convenient sources.

Where I live the main industry is mining, the miners live hundreds, if not thousands, of miles from their work.

Its all FIFO: fly in, fly out.

FIFO is way more efficient than building permanent "colonies" at the site of mineral deposits.

 

[mheslep]

Nothing that says you can't do both;

Money, especially in the event colonization scales up to millions.

Space Colonization is in general more exciting

Perhaps. Certainly more hyped, more Hollywood. Space travel and exploration is exciting, with the danger being part of that; I suspect colonization would become much less exciting over time. In the event of an actual colony, it may be that the one affording 2 way simultaneous communication is more interesting.

and finding unknown life in the oceans is still going to be 'simply' undiscovered Earth Life, while the possibility of finding truly Alien life will be a monumental moment in scientific history.

Manned spacecraft and colonization of Mars are not required to explore for microbial life there. Also, If extraterrestrial life discovery is truly the goal, then it seems to me some kind of major investment in orders of magnitude better space based observation of remote solar systems is far more productive. Perhaps some interferometry with a 1000 instruments along an AU sized baseline.

 

[Algr]

Alien life on Mars would put the breaks on colonization because our presence would likely wipe it out, or turn us into terminator zombies.

Ceres might be a better place for a colony then Mars.

 

[rootone]

Ceres is similar to the Moon as an environment, but half the size and a lot more distant.
Unless there is something very useful there that isn't available on the Moon what why would it be better?

 

[Algr]

There IS something. Plentiful water. Mars and the moon would both have us trying to squeeze water out of damp sand.

 

[lifeonmercury]

If money were no object, could we establish a colony on the Moon within 10 years that could survive indefinitely if everyone on Earth died? Let's say every nation on Earth contributed 25% of its GDP for 10 years to achieving this. Would it be possible?

 

[Algr]

If money were no object, we could have started that in 1970.

 

[rootone]

If money were no object, could we establish a colony on the Moon within 10 years that could survive indefinitely if everyone on Earth died? Let's say every nation on Earth contributed 25% of its GDP for 10 years to achieving this. Would it be possible?

Possible yes, Feasible no.
There would be interminable politics surrounding which nations are entitled to do what with the colony.

 

[mfb]

I'm referring to human habitat waste - why would you create toxins in the habitat? As for chemistry and manufacturing processes, if they use up water, maybe find another process, or recycle that water in it's own closed loop.
It would be relatively easy to distill water using low pressure and so yes, you can recover almost every drop out of most types of toxic waste.

Every colony approach will need a lot of chemical industry, which will produce similar waste as on Earth. You can recycle it, yes, with a huge effort. But you can also dig up new ice conveniently located close to the station. But only on Mars.

But my point is this - the (expensive) Apollo program stopped when people got bored with it. Now we have basically the same idea for a mission to Mars, and won't that mission just stop when people get bored? And for China it's the same kind of national pride to be the second nation to the Moon (they hope). Maybe the first nation to Mars, they will be hoping too.

You brought up the Chinese Moon program...

I'd also point to the Biosphere II project that seems to indicate that we have no idea how to build an ecosystem on Mars that could provide food for us long term without massive constant input from Earth.

A colony on Mars would have unlimited supply of CO2 and ice, something biosphere 2 did not have. Unlike Biosphere 2, a Mars colony would not try to to mimic all sorts of different biotopes in it, and would focus on the most efficient plants to get food. Oxygen is a nice by-product, but not necessary.

If money were no object, could we establish a colony on the Moon within 10 years that could survive indefinitely if everyone on Earth died? Let's say every nation on Earth contributed 25% of its GDP for 10 years to achieving this. Would it be possible?

10 years sound super optimistic. Using the estimated cost of SpaceX's ITS (there would be several similar projects with so much money), but with single-use transport ships because we won't use more than one or maybe two transfer windows: $200 million for ~300 tons. Let's be optimistic and say $500/kg, mass production would help. $100 trillion GDP per year, 25% over 10 years: $250 trillion. That would allow transporting 500 million tons to Mars. At 100 tons per person (maybe pessimistic, but we don't have so much time for R&D), that corresponds to a population of 5 million. Not bad. R&D costs should be negligible on that scale, materials shipped to Mars should be much cheaper than $500/kg as well. Unfortunately scaling that far won't work: we cannot have 1/4 of the world population work on building spacecraft s. We don't have so many raw materials, and we don't have so many experts.

 

[mheslep]

Let's say every nation on Earth contributed 25% of its GDP for 10 years to achieving this.

For many of the developing countries in the world, there is no spare GDP. Cutting out a 1/4 in these places means cutting out the bone, i.e. the water supply, food, basic necessities.

 

[Dale]

Why choose from big rocks in space when floating space stations are already proven and are more feasible.

I do like the idea. Floating space stations can also be somewhat mobile to go to places where resources are, and then leave to go elsewhere.

 

[Chronos]

The moon is a terrible option, while much easier to reach it has almost zero terraforming options - very little water, virtually no atmosphere and no useful soil chemistry. It would take eons to convert the moon into anything resembling a viable biosphere. Mars would be much easier, it has significant water reserves, a tenuous atmosphere, and a soil composition potentially capable of supporting life. The down side is it is vastly distant compared to the moon. I believe the moon is entirely viable as a base, with sufficient support materials to make reaching Mars a realistic option.

 

[Stavros Kiri]

It's certainly a good question, but I think there are two main reasons that people have fixated on Mars rather than the moon:
(1) Mars has a day/night cycle very close to Earth. The moon has a 4 week day/night cycle. During the two week night, it gets extremely cold, and solar power is not available for generating energy.
(2) Mars has a ready supply of water, which is essential for any human colonization. The moon may have water in permanently shadowed craters at the poles, but this has not been proven. Elsewhere on the moon is extremely dry, so water does not appear to be available.

I think another (3rd) very important reason is that the moon can never have atmosphere, because of the low g (escape velocity is much smaller on the moon than on earth, thus gasses escape in space ...).
That, besides giving no terraforming capabilities, would imply huge indoor controlled life-support facilities, that would increase the cost too much.

Also I think the smaller gravity on the moon can in fact be a problem by itself. Remember that g on the surface of the moon is only 1/6 of the g on the surface of the earth.
[+ no atmosphere would imply no protection from asteroids and stuff, as well as from cosmic and other harmful radiation (even from the sun - no ozon ...).]

 

[Al_]

[+ no atmosphere would imply no protection from asteroids and stuff, as well as from cosmic and other harmful radiation (even from the sun - no ozon ...).]

On Mars the radiation is also a problem, so that you would need to cover habitats with metres of Mars dirt to protect people inside. And even some fairly small meteors would make it through the thin atmosphere to the surface. There is no ozone on Mars either! Basically, for these things it's not so different from the Moon.

 

[Al_]

I think another (3rd) very important reason is that the moon can never have atmosphere, because of the low g (escape velocity is much smaller on the moon than on earth, thus gasses escape in space ...).
That, besides giving no terraforming capabilities, would imply huge indoor controlled life-support facilities, that would increase the cost too much.

Woah! Terraforming is waaay far in the future. Just look at the amount of stuff needed! Even to use Mars own water, that's millions of mirrors or thousands of nukes to melt it, hundreds of years for it to happen.
This thread is about colonising, not terraforming.
Yes, keeping it indoors and doing life support is much more possible - have you ever seen those big industrial greenhouses that grow tomatoes and such? That's the kind of thing you need for a colony.
So, I think the Moon is much easier to colonise because it's closer.

 

[mfb]

Moon is closer purely in terms of travel time (signals and rockets). In terms of required rocket size to reach it (delta-v requirements), it is actually further away until we build a lunar space elevator. In terms of Earth similarity and availability of everything interesting for a colony it is much worse.

By the way: Hydrogen, oxygen and potentially carbon are also needed as rocket fuel, which will always be wasted. If you want to re-use rockets and/or get anything from the colony back to Earth, you'll need a constant supply of it.

 

[Al_]

But you can also dig up new ice conveniently located close to the station. But only on Mars.

On the Moon you can dig up water ice too!
It is well established that there is enough water on the Moon to allow us to colonise it, maybe a city size.
Living in sealed habitats, with very little escape of water.
"Now that we have detected water that is likely from the interior of the moon" http://www.jpl.nasa.gov/news/news.php?release=2013-262
The surface temperature at the poles is -110 C. It is not known exactly how deep the cold goes, but the core is maybe 2000 C, so you can drill something like 5% of the way down before it's above zero. Pretty deep. At depth, under pressure, maybe there is liquid water! Certainly any water there from the formation of the Moon would still be there.

 

[Al_]

Moon is closer purely in terms of travel time (signals and rockets). In terms of required rocket size to reach it (delta-v requirements), it is actually further away until we build a lunar space elevator. In terms of Earth similarity and availability of everything interesting for a colony it is much worse.

By the way: Hydrogen, oxygen and potentially carbon are also needed as rocket fuel, which will always be wasted. If you want to re-use rockets and/or get anything from the colony back to Earth, you'll need a constant supply of it.

In terms of rocket size, the delta-V is not all that determines rocket size. If you carry 5 times as much stuff, you need 5 times as big a rocket.
(And btw, on the Moon, it is easier to build a magnetic laucher than a space elevator.)

 

[mfb]

It is well established that there is enough water on the Moon to allow us to colonise it, maybe a city size.

Reference?
Traces of water and relevant amounts of water are different things.

The interior temperature profile is not uniform with radius.

Certainly any water there from the formation of the Moon would still be there.

Or hydrogen and oxygen bound to other elements.
This is a science forum. You cannot randomly make up claims without evidence backing them.

In terms of rocket size, the delta-V is not all that determines rocket size. If you carry 5 times as much stuff, you need 5 times as big a rocket.

Obviously. But carrying it 100 times further does not change the rocket size. Going to Moon one-way (=the main payload direction) is harder than going to Mars. The magnetic launcher is not a magnetic lander, unless you are really, really precise with landings. A magnetic launcher big enough to launch a rocket (which landed earlier) will be extremely massive.

 

[Stavros Kiri]

On Mars the radiation is also a problem, so that you would need to cover habitats with metres of Mars dirt to protect people inside. And even some fairly small meteors would make it through the thin atmosphere to the surface. There is no ozone on Mars either! Basically, for these things it's not so different from the Moon.

True for now, but Dr Zubrin* has a plan to change all that a lot faster creating exact earth-like atmosphere, warming it up with greenhouse effect (just like we do on earth), to make sure it's a good colony plan.

In other words: can't live indoors for ever! ...

* Check out:
(e.g. especially 1hr 13'&14'+ spot on the video)

 

[Al_]

Food you can grow, energy you can harvest other stuff you could mine from convenient sources.

Where I live the main industry is mining, the miners live hundreds, if not thousands, of miles from their work.

Its all FIFO: fly in, fly out.

FIFO is way more efficient than building permanent "colonies" at the site of mineral deposits.

Which brings up the idea that tele-presence (Virtual Reality plus remote robots) will make a big impact on space. Maybe live in orbit of a moon or asteroid, or underground, and work on the surface or in a deep, dangerous mine! You basically work like you are the robot, but no pressure suit, no worries about meteorites, radiation, mine collapses, oxygen, toxic gases. You need to be close enough so that the signal delay is a fraction of a second, so maybe 1000km away. You might live in a large, luxury, habitat. Maybe like a cruise liner with low gravity and robots!

 

[Al_]

This is a science forum. You cannot randomly make up claims without evidence backing them.

I gave a reference. The NASA link.

 

[Stavros Kiri]

Woah! Terraforming is waaay far in the future. Just look at the amount of stuff needed! Even to use Mars own water, that's millions of mirrors or thousands of nukes to melt it, hundreds of years for it to happen.
This thread is about colonising, not terraforming.
Yes, keeping it indoors and doing life support is much more possible - have you ever seen those big industrial greenhouses that grow tomatoes and such? That's the kind of thing you need for a colony.
So, I think the Moon is much easier to colonise because it's closer.

(+see/cf. my previous reply) You really need to see Dr Zubrin's plan etc., which, as far as I know, is the prevailing plan to go. Colonizing and terraforming Mars go together hand-in-hand, if you want to have a permanent successful colony. In other words: you can't live indoors for ever!
You better create true earth-like atmosphere (they can do it almost within the century). The plan and the goal is to do that! ...

[e.g. see "The Mars Underground" on YouTube]

e.g. on the following edition:



around on 1hr 10' spot Dr Zubrin sais that Mars can be terraformed by 23rd century, not 33rd! ...
They have a good plan.

 

[Al_]

But carrying it 100 times further does not change the rocket size

But, in practice, you need to carry more stuff. Food, shielding, spares, tools, maybe oxygen and water. And more fuel to get home, carrying more stuff back with you so you can survive the trip back..

 

[Al_]

In other words: you can't live indoors for ever!

You can't live in confined spaces for ever, true.
But how about walking between and around a shopping mall, an indoor park, botanic garden, a spa, a swimming pool, sports arena, greenhouse?
And then go to the office and put on a VR headset and do your work operating a robot that works outside.
I don't think people would feel claustrophobic doing that. They could live inside forever, I think.

 

[Stavros Kiri]

I' ve added to my edittings ... above (cf. ...), e.g. refs full science videos from YouTube, not quite sci-fi according to Dr Zubrin's plans, following the "Mars One" and "Mars Direct" missions and plans (etc.). All realistic ...

 

[Stavros Kiri]

You can't live in confined spaces for ever, true.
But how about walking between and around a shopping mall, an indoor park, botanic garden, a spa, a swimming pool, sports arena, greenhouse?
And then go to the office and put on a VR headset and do your work operating a robot that works outside.
I don't think people would feel claustrophobic doing that. They could live inside forever, I think.

I am right with you there, I almost agree, almost thrilled and excited too about such solutions, if there is no other way ...

But if we have a choice, and a better plan (e.g. like Dr Zubrin's), I would choose the latter, as it resembles (once completed) "mother earth" ...
And there is nothing like Home and "Mother Earth"! ... (even if we have to call it "mother (or father) Mars" ... [in the unforseeable future ...])
[Indoors and VR , even for nostalgia, is just a substitute, and may not be good enough ...]

 

[Stavros Kiri]

But for now we are only on the space station (living humans) and even a simple spacewalk takes a lot of effort! [As a matter of fact there is one going on right now:
https://www.physicsforums.com/threads/nasas-spacewalks-on-the-iss-jan-6-and-jan-13.900129/ ]

 

[dkotschessaa]

Why choose from big rocks in space when floating space stations are already proven and are more feasible.

You're looking for logical reasons, but an irrational, yet innate compulsion of human beings to explore the world and the cosmos may also play into the picture.

-Dave K

 

[Al_]

Reference?
Traces of water and relevant amounts of water are different things.

The interior temperature profile is not uniform with radius.Or hydrogen and oxygen bound to other elements.
This is a science forum. You cannot randomly make up claims without evidence backing them.

Yes, but the NASA link goes on to say the traces they found on the surface are just the start - they found evidence of primordial water deeper down, chemically bound into rocks.

I take your point about the temperature profile. But even a worst estimate says there are many kilometers of depth where ice can sit. And below that, with pressure, water can exist. The 0 C boundary gets shallower as you move away from the poles. So we can ask the question, is there any, and how much?

As you say, it might be chemically bound to other elements. The closest analogies we have are stony asteroids and Earth. In both cases, water or ice often exists in the primordial state. Some is chemically bound to rocks, but often some is free. Free water moves, and gathers in reservoirs.

I'm saying there is a smoking gun for Moon water.
Prospecting and digging/drilling for it is much easier than on Mars.
If it's there, we can colonise the Moon faster, easier, cheaper, more profitably and more safely than Mars.
And I'm saying even if it's all chemically bound, that's not going to pose as big a difficulty as going to Mars.

 

[rootone]

If there are indications of substantial free ice deposits under the surface on the Moon that does improve the feasibility of at least maintaining a small manned base there.
I think that so far though there only have been some indications of subsurface ice near the poles, whether or not in useful amounts unknown at present.
Extracting water from silicate rocks and other minerals is probably never going to be an economic proposition.