Why colonize Mars and not the Moon?

[litup]

The usual two-way trip plans have 4-6 months in transit, about 1.5 years on the surface and 4-6 months back. Total mission duration ~2.5 years, more than half of the mission at the surface of Mars.
Changing those times significantly would need much more powerful rockets.As self-sufficient as possible, especially for bulk material, is certainly interesting to limit transportation needs. You don't want to produce computer chips on a Mars colony (unless the colony is huge already), but you certainly want to produce most of the goods you use there.A colony on Mars would tell us a lot about the ecosystem on Earth as one of many byproducts.

Sure, more powerful rockets based on today's chemical rockets but there are others afoot, like VASIMIR and so forth, where you would need some kind of multimegawatt power source, most likely nuclear. At even 1/10 g trip time is about a week or two. One problem about Mars: Not much in the way of magnetic fields aroun Mars. That however can be solved if and when we develop room temp superconductors, I envisioned a superconductive loop around the equator, a few turns with about 20,000 amps flowing and you get a planet wide field like Earths only a bit weaker, maybe half gauss or so, still good enough to stop the bad guys coming from the sun Next would be to build up some kind of atmosphere. Not in my pay grade:) but with a planet wide field, the sun would not be stripping O2 from the atmosphere like it has for the past few billion years. If the superconductor loop was room temp plus a bit, the field would never go away unless somebody blew up the cable.

 

[mfb]

How do you justify that? [If you already have earlier and I missed it you can just quote it ... ; it's been a long discussion ...] Are you sure that with a little over 1/3 of the gravity on Earth we can have on Mars a thick and high enough earth-like-terraformable atmosphere (including ozon layer etc ...)? I haven't done the math.

Simple comparison of the gravitational potential and the mean thermal energy of molecules.

The Martian escape velocity is 5.03 km/s, at 100 km height this drops a bit to 4.96 km/s. A single oxygen atom needs an energy of 2.05 eV to escape. At an exosphere temperature of 300 K (source), the average kinetic energy is just 0.039 eV, a factor 50 below the energy needed to escape. For oxygen molecules, the factor is 100. Thermal escape of oxygen (and nitrogen) is completely negligible. For hydrogen molecules, the ratio is 6.6 - some will escape. For single hydrogen atoms, the ratio is just 3.3 - they have a significant chance to escape. At 300 K, the fraction of single hydrogen atoms should be small, however.@litup: As discussed, such a magnetic field could be interesting a million years in the future, it is irrelevant for the next thousands of years. We could build it with nearly present technology (cool the superconductors). If there are humans that want a magnetic field on Mars in a million years, they will probably solve that issue with technology we cannot even imagine today.

 

[1oldman2]

Well, this is the direction in which the "powers that be" are currently leaning.
http://www.spaceflightinsider.com/o...irect-nasa-moon-establish-sustained-presence/

 

[mfb]

We'll see if that bill gets passed. Even if it does, it is something beyond the timescale of the current administration. The current official SLS plans are an unmanned maiden flight in 2018, and a manned mission to lunar orbit in 2021. I heard that the components are behind schedule, and the 2018 flight will nearly certainly get shifted. So let's say we have a maiden flight in 2019 and a manned mission in 2022. A lunar lander making an unmanned flight in 2024, with a manned mission 2025?

 

[Al_]

Rovers to Moon, humans to Mars?

For a colony, they need each other. They need to be in the same place.

current rovers cannot do many things a human can

A rover is not a multi-purpose robot. See NASA's space robot, Robonaut. https://robonaut.jsc.nasa.gov/R2/

I realize the following pushes the limits of acceptable sources for this thread, I did find it relevant (as well as a little dated) enough to mention it though.
Its just possible there may be some points worthy of discussion as its in the general subject area of the thread.
http://blogs.discovermagazine.com/crux/2014/09/08/where-build-off-world-colonies/

Touches on the important question of gravity : How high does gravity have to be before it is strong enough to raise a child healthily?
Short answer : nobody knows. But there are ways to find out. For example, raise apes in low-g. Monkeys on the Moon!
Maybe build a rotating space station at say 0.9g and raise children there. And adults living a long time in Moon gravity - what would that do? We could and should start to research these questions.

The movie "The Space Between Us" has a plot twist where a boy raised on Mars is too unused to the gravity to survive on Earth. I am not aware of any good evidence to either justify or refute this.

Show us reasonable economic estimates that any metal on the Moon is profitable to extract and sell on Earth.

I was referring to the case when a Lunar colony is already underway, and I was not referring to Nickel.
Gold, Platinum or Palladium, perhaps. It also depends on having a Lunar source of rocket fuel available, and the ability to make crude heat shields on the Moon. Maybe make them from basalt fibre and aluminum?
The rocket can be re-used. After lauching the payload into Earth re-entry orbit it heads back to the Moon.

 

[sophiecentaur]

Eventually, if we had the technology to transform Mars into a habitable planet,

That concept always makes me smile. So far, we are doing a pretty good job of transforming Earth into an Uninhabitable planet. You first need to 'transform' the whole attitude of humans to their environment. I'm not suggesting it's impossible but I wouldn't bet my last £ on it.

 

[mfb]

For a colony, they need each other. They need to be in the same place.

Humans will always have robots around, but the other direction is not true.

A rover is not a multi-purpose robot. See NASA's space robot, Robonaut. https://robonaut.jsc.nasa.gov/R2/

The https certificate is broken.
Rovers are the best robots we have now. Yes, they will improve in the future, but for now humans are far superior to robots, even if we compare humans to remote-controlled robots.

 

[Al_]

I just want to remind you that colonisation is not the same as terraforming.
Colonisation is a much earlier step. It requires enclosed, pressurised habitats comparable in size to buildings on Earth, as opposed to planetary scale modifications.

 

[Al_]

Rovers are the best robots we have now

That's a matter of opinion.
http://www.bostondynamics.com
http://robonaut.jsc.nasa.gov/R2/

 

[nikkkom]

> Show us reasonable economic estimates that any metal on the Moon is profitable to extract and sell on Earth.

I was referring to the case when a Lunar colony is already underway, and I was not referring to Nickel.
Gold, Platinum or Palladium, perhaps.

"Perhaps" is not a reasonable economic estimate. It's a sign you do not know.

Today, after we spent some 60 years of R&D on launch vehicles, a kilogram of any cargo sent from Earth to LEO on a cheapest rocket costs about 1/10 of one kilogram of gold.

Lunar launch infrastructure would need about a century of active development to reach this efficiency.

 

[Mark Harder]

I personally wouldn't want to live on Mars during the pioneering phase since most of my time would be spent inside a convivial bubble of some sort. I need to be away from the totally humanized environment every day, or I get stir-crazy and depressed.* There's an interesting article in the latest Sci. Am. about the effects of radiation on our central nervous systems, and it isn't pretty. I'm 70 yrs old, and I need every brain cell I can hang on to. On any planetoid without a heavy atmosphere, you would be spending most of your outdoor time in a shielded vehicle, not in your bubble-suit wandering around by foot. At least Mars is further from the radiation-spewing sun than the moon.

AFAIK, no evidence for natural underground shelters have been found on the Moon. As certain as the presence of H2O on Mars is the presence of caves. Perfectly round, dark holes have been located on the Martian surface. Given the volcanic nature of the matrix, the caves would likely be lava tubes, such as those found on Terra. Since these are formed in lava moving within the right range of flow rates, gravity will influence the range of rates. The moon is significantly smaller than Mars, so its gravity is much smaller than that on Mars. Thus, it's possible that Lunar lava flowed too slowly to leave behind the sub-surface voids that are lava tubes. Why caves? Three reasons I can think of. First, the dense basalt cover will to some degree absorb cosmic and solar rays. Second, on Terra cold lava tubes, even some in temperate regions (like OR and N CA), water as ice may be found. BTW, some of these places are quite beautiful. So a local, 'indoor' water supplies might be available. And finally, roof floor and 2 walls are free additions to the properties. All that would be needed to create a habitat would be end-pieces containing air locks, etc. Of course, a way of vacuum-sealing these to the rock surfaces would need to be developed, something like polyurethane foam, perhaps?

* I attended college in Chicago, and one late night, to take a break from writing a long term paper I walked over to a window and looked out. I spotted a star, visible up there over the glare of the street lamps, and the thought occurred that unlike the urban environment in which I was encased 24/7, the star was not a creation of people. I was startled by so trenchant an insight, which I tried to share with my friends, who were dissapointingly nonplussed by the notion that anyone would think to mention so self-evident a conclusion. I don't care. To me, knowing that such a natural object, incapable of being created by any human, existed outside the all-providing bubble we call civilization.

 

[Mark Harder]

One could take advantage of Moon's low gravity to create and launch space vessels with planetary destinations, a way station in other words. Isn't there supposed to be lots of Helium-3 on the lunar surface? I recall seeing that somewhere, perhaps here. The idea being that fusion power sources are much easier to design and build using He-3. But I wouldn't want to make a home of the moon.

 

[rootone]

One could take advantage of Moon's low gravity to create and launch space vessels with planetary destinations, a way station in other words. Isn't there supposed to be lots of Helium-3 on the lunar surface? I recall seeing that somewhere, perhaps here. The idea being that fusion power sources are much easier to design and build using He-3. But I wouldn't want to make a home of the moon.

Manufacturing of rockets on the Moon makes sense up to a point, the problem is you have to build the manufacturing infrastructure first,
and all of that all has to come from Earth, lots and lots of it.
It would require substantial mining and metal production industries, which in turn would require industrial scale power supplies.
There would need to be some permanently occupied human habitats to house the people responsible for operations .
A large industrial complex could not be expected to function very well if operated and maintained only by remote controlled robots.
As for He3, yes it is a potential power source - once we have a fully working fusion reactor, but then you first have to build that reactor on the Moon.
Trillions of investment over probably at least 2 decades could be needed before the first space vehicle was produced.

 

[Al_]

"Perhaps" is not a reasonable economic estimate. It's a sign you do not know.

Today, after we spent some 60 years of R&D on launch vehicles, a kilogram of any cargo sent from Earth to LEO on a cheapest rocket costs about 1/10 of one kilogram of gold.

Lunar launch infrastructure would need about a century of active development to reach this efficiency.

"from Earth to LEO" that's the wrong direction. Going the other way is much easier. Compare the Apollo launch from Earth with the launch back from the Moon.
"Lunar launch infrastructure" I'm not assuming any infrastructure except fuel production. Best case, that can accomplished by landing a single mining unit containing rovers.
"after we spent some 60 years of R&D on launch vehicles" Which includes vehicles that launch from the Moon.

 

[nikkkom]

"from Earth to LEO" that's the wrong direction. Going the other way is much easier.

Really? How much would it cost for me today to ship one kg from the Moon to Earth?

 

[Al_]

all of that all has to come from Earth, lots and lots of it.

Which planet did Earth's infrastructure come from?
On Earth we built it up, step by step, from dirt, by hand.
On the Moon, our remote controlled robots can build it up, step by step, from dirt, by gripper.
And the steps can be quicker, because we know where we're headed second time around.
(and some clever fiddly bits like electronics can come from Earth)

 

[Al_]

Really? How much would it cost for me today to ship one kg from the Moon to Earth?

I meant, much easier in physical terms. If there is a transport rocket in place. I wasn't talking about today, but the possible near future.

Here's a scenario:
A small drone rocket could get a payload of precious metal and fuel and launch from the Moon to LLO. Then it's ion drive takes a month or so to transfer it to LEO. It does a quick de-orbit burn, releases it's payload, and a quick burn to get back to orbit. The payload re-enters the atmosphere and hard lands in the desert. The drone then uses it's ion drive and takes a couple weeks or so to transfer to LLO. Another rocket burn takes it down to a pre-arranged spot on the Moon. Here, the robots load it up with another payload and more fuel.

Re-using the vehicle keeps the costs way down. It can be made on Earth.
Then the cost per trip is mostly the fuel cost, and that is the unknown factor.
We know there is ice on the Moon. If we can build a small mining unit, and it runs for a long time, the cost could be spread over a long time. We use solar power to make fuel from the ice.

 

[Drakkith]

On the Moon, our remote controlled robots can build it up, step by step, from dirt, by gripper.
And the steps can be quicker, because we know where we're headed second time around.
(and some clever fiddly bits like electronics can come from Earth)

Where do you get all of the thousands of different compounds, chemicals, fuel, and other resources required to find, gather, and refine the building materials? How do you smelt ore without limestone or another type of flux? How many of these are readily available on the Moon?

 

[nikkkom]

I meant, much easier in physical terms. If there is a transport rocket in place. I wasn't talking about today, but the possible near future.

Here's a scenario:
A small drone rocket could get a payload of precious metal and fuel and launch from the Moon to LLO. Then it's ion drive takes a month or so to transfer it to LEO. It does a quick de-orbit burn, releases it's payload, and a quick burn to get back to orbit. The payload re-enters the atmosphere and hard lands in the desert. The drone then uses it's ion drive and takes a couple weeks or so to transfer to LLO. Another rocket burn takes it down to a pre-arranged spot on the Moon. Here, the robots load it up with another payload and more fuel.

Re-using the vehicle keeps the costs way down. It can be made on Earth.
Then the cost per trip is mostly the fuel cost

If you can freely assume any infrastructure you wish to already exist, then (for example) the cheapest potable water is on Enceladus, and it's cheap (albeit somewhat slow) to transfer it from there to basically anywhere. Let's get on with a project to irrigate Sahara with it.

But in practice, (non)existence of infrastructure is very important factor, actually the key factor, and largest difficulty in planning space colonization is how to get from a state where we have nothing there to the state where we successfully establish said infrastructure there - with all political and financial constrains of the real world.

 

[1oldman2]

Worthwhile browsing concerning research and processes.
http://spaceresources.mines.edu/index.htm
https://www.nasa.gov/pdf/164302main...&RoboticTechnology_SpaceApplication_CKing.pdf

 

[sophiecentaur]

Let's get on with a project to irrigate Sahara with it.

I assume you are joking here. The cost of desalination of all the trillions of tons of seawater available on Earth, using Terrestrially based solar power plants can surely not be more than what you propose. Desalination is only done when the need is dire but you can see examples all over the world. Just look at this link.

 

[mfb]

That's a matter of opinion.
http://www.bostondynamics.com
http://robonaut.jsc.nasa.gov/R2/

How many of those have been outside Earth?
I don't say that there is no progress, but those approaches are still far away from being used outside Earth.

A small drone rocket could get a payload of precious metal and fuel and launch from the Moon to LLO. Then it's ion drive takes a month or so to transfer it to LEO. It does a quick de-orbit burn, releases it's payload, and a quick burn to get back to orbit. The payload re-enters the atmosphere and hard lands in the desert. The drone then uses it's ion drive and takes a couple weeks or so to transfer to LLO. Another rocket burn takes it down to a pre-arranged spot on the Moon. Here, the robots load it up with another payload and more fuel.

Then you have to carry all the landing fuel, the engine and so on to Earth and back. If rockets are used at all, two different systems look more efficient. One system brings stuff to LLO, another system cycles between LLO and Earth.

I would try to avoid big rockets completely. Build a lunar space elevator. A practical cable can be as light as 50 tons and can be built with existing materials. You can produce it on Earth, a single Falcon Heavy or SLS launch can deliver it to Low Earth Orbit, other rocket launches can then bring it to L1 (SLS Block 2 might have that capability in a single launch, ITS will laugh at that payload). Add a counterweight and Moon ground infrastructure.
Delta_v between space elevator and atmosphere-grazing highly eccentric Earth orbit: ~600 m/s.

You still have to invent a largely autonomous mining industry on Moon, with everything either produced locally (how?) or shipped to Moon (expensive).

Isn't there supposed to be lots of Helium-3 on the lunar surface? I recall seeing that somewhere, perhaps here. The idea being that fusion power sources are much easier to design and build using He-3. But I wouldn't want to make a home of the moon.

By far the easiest fusion reaction is D+T. We don't have power plants based on that yet. Even in the most optimistic case, fusion with He-3 is much more challenging, and it is unclear if it can work at all.

The surface of Moon has up to 10 parts per billion He-3 by mass. You would have to process a whole cubic kilometer for ~20 tons of He-3. Fused with lithium or deuterium*, that gives 10¹⁹ J, about 1/3 of that would go to electricity. If we let the fuel cost 2cent/kWh, our cubic kilometer of regolith gives He-3 for $20 billion dollars worth of electricity.
As comparison: A poor gold mine on Earth has 1 grams per ton, filtering a cubic kilometer of rock on Earth gives gold for a market price of $100 billion. Good mines have more than 10 times that concentration.
Even if we would have fusion reactors that could use He-3, filtering it out of cubic kilometers of rock on the Moon would be extremely expensive.

He-3 from the Moon is a nice science fiction story, but the numbers don't work out.*there is also the option of He-3 He-3 fusion: it might give a better conversion rate to electricity, but it also needs twice the fuel per energy released, so it doesn't change the conclusion

I would say that the amount of money spent on Aid should be at least as great as that spent on fundamental Science and Space research.

$25 billions/year are directly spent on humanitarian assistance (source, for 2014, $22bn in 2013).

The total NASA budget is $17.5 billion (2014, 2015), but a significant fraction of that is for Earth observation, Sun observation, material science for Earth-based applications and so on. It is impossible to find a number "not Earth-related".
Total ESA budget is $5.6 billion (2016), same problem here.
Roscosmoc has a budget of about $3 billion (2015, I don't speak Russian but the budget should be 186.5 billion rubles)
India spends $1.1 billion (http://www.isro.gov.in/sites/default/files/article-files/budget-accounts/outcomebudget2016-2017.pdf )
The Chinese don't seem to make their numbers public.
All other space agencies are negligible. Currency conversions done with the current exchange rates.

Global government funding for space agencies combined (and see above: a good fraction is science for Earth) is at the level of direct humanitarian aid. That does not include research that helps other countries and various other forms of aid.

 

[1oldman2]

More "fun facts" here.
https://arxiv.org/abs/1609.00737
"It is roughly estimated that developing a lunar outpost that relies upon and also develops the supply chain will cost about 1/3 or less of the existing annual budgets of the national space programs. It will require a sustained commitment of several decades to complete, during which time science and exploration become increasingly effective."

https://arxiv.org/abs/1608.01989

Phobos is of interest also.
https://arxiv.org/abs/1702.00335

 

[Dale]

Come on people. Closed for thread cleanup.

Thread reopened. This is not a thread for discussing religion, God, or aid to developing nations. Politics can be discussed but keep it directly relevant. E.g how much it would cost relative to current budgets, not what else we could spend it on.

 

[Aditya Shende]

See
The distance between the centre of the Earth and centre of the moon is increasing at a speed of about 1.5 inches i.e. about 3.8cm every year
So
There will be a point when the moon would probably break free from the Earth's orbit
So, if we colonize moon , we may end up dying anyways[emoji28]
But that's not what we want right?[emoji28]
On the other hand
The Mars is permanently in its orbit
It isn't going far away
So
Mars is planned to be colonized
And not moon

Well
As per the 4 langrangian points
The nearest langrangian point to Earth is near the moon
So we could think about colonizing near the moon
But
If the moon keeps moving away
The langrangian point would eventually become unstable
So
We cannot do that either
That's y
Mars

 

[rootone]

At 3.8 cm a year it's going to take hundreds of millions of years for the Moon to escape Earth's gravity.
Human beings have existed for less than 1 million years.

 

[Drakkith]

See
The distance between the centre of the Earth and centre of the moon is increasing at a speed of about 1.5 inches i.e. about 3.8cm every year
So
There will be a point when the moon would probably break free from the Earth's orbit

Not true. Tidal forces are responsible for transferring energy from the Earth's rotation to the Moon, moving it into a higher orbit. In the far future the Earth will be tidally locked to the Moon and no more energy will be transferred. The Moon will then be locked into its orbit. There will never be a time when the Moon will break free of the Earth.

 

[Aditya Shende]

Mentor note: Merged some posts. Please use the edit function.

Not true. Tidal forces are responsible for transferring energy from the Earth's rotation to the Moon, moving it into a higher orbit. In the far future the Earth will be tidally locked to the Moon and no more energy will be transferred. The Moon will then be locked into its orbit. There will never be a time when the Moon will break free of the Earth.

Oh yeah
Sorry
I missed that out
as its distance from Earth decreases and its tidal forces get weaker so,this alone should be enough to prevent our satellite from ever leaving orbit around Earth

But still
Colonizing on Mars is better than colonizing on moon

U see
The moon has lots of issues when it comes to colonizing, because
1)The moon has no atmosphere and as such humans are susceptible to various space radiation.
2)The moon is made of regolith which is basically microscopic jagged glass. Its destructible to human breathing and equipment. Due to it being so small it can get into any human habitation on the moon even if sealed.
3)The day night cycle there is about 29 days for day and 29 days for night, which makes things very cold and very hot from 200 F to -300 F. Again very bad for human technology. Not to mention our psychology.
4)The low gravity will make everything difficult including on our bodies. Yeah I know there is micro gravity on the ISS, but that is a test bed and people will not colonize it. If you plan on living in space, you will have to spin things to make gravity. There is some experiments that show that human fertilization depends on certain amount of gravity, more than likely humans will not be able to procreate on the Moon.

Mars on the other hand is almost Earth like in many ways, from a better gravity (still a bit low but better than the Moon). Its day night cycle is close to Earths. It has a small atmosphere and we can make more there with Terra forming. Basically its further away, but is a better place to live for humans and our technology.

 

[sophiecentaur]

There will be a point when the moon would probably break free from the Earth's orbit

Did you work out how long before that happens?

I would try to avoid big rockets completely. Build a lunar space elevator.

A nice thought on the face of it but it's a shame that a space elevator needs to be in 'stationary' orbit around its parent object and the rotation rate of the Moon is 1/month. I used the formula in this link and I think that gives a tether length of about 100X10³km. I think that could involve gravitational problems from Earth.

 

[mfb]

A nice thought on the face of it but it's a shame that a space elevator needs to be in 'stationary' orbit around its parent object and the rotation rate of the Moon is 1/month. I used the formula in this link and I think that gives a tether length of about 100X10³km. I think that could involve gravitational problems from Earth.

You should know that I check the numbers before suggesting things.
The "gravitational problems from Earth" are exactly what makes the tether possible. Instead of the geostationary orbit, a lunar space elevator uses the Earth/Moon L1 point (or L2 on the far side) as neutral point. It is 56,000 km above the surface of Moon, so you need a longer tether (longer than 56,000 as it has to go to the counterweight), but it can be very thin, and it does not even need tapering.
Wikipedia has a longer article and also references about individual proposals.

 

[lifeonmercury]

Any ideas about how to reduce the amount of dust in the air on Mars?

 

[sophiecentaur]

Instead of the geostationary orbit,

Luckily, it would be near Lunostationary (or Selenostationary, perhaps) because of the Moon's gravitational locking. If the Moon were to rotate at a different rate it would not be possible to use the Lagrange point. A bit of slop in the tether would allow for libration or you could have a man on a winch to keep it under control (haha). Strength would be far less of a requirement. Perhaps today's technology?

 

[sophiecentaur]

Any ideas about how to reduce the amount of dust in the air on Mars?

I can't imagine it would be any more straightforward than fixing the Earth's weather. I would think you'd just have to live around it.

 

[mfb]

Perhaps today's technology?

As I said already: We have materials today that work. For the aerospace industry, those materials cost something like 10-100 dollars per kilogram. 50 tons would cost 500,000 to 5 million dollars. Even with the worst case, and with a factor 10 "it is space" markup, it is still below the launch costs.

 

[Mark Harder]

Manufacturing of rockets on the Moon makes sense up to a point, the problem is you have to build the manufacturing infrastructure first,
and all of that all has to come from Earth, lots and lots of it.
It would require substantial mining and metal production industries, which in turn would require industrial scale power supplies.
There would need to be some permanently occupied human habitats to house the people responsible for operations .
A large industrial complex could not be expected to function very well if operated and maintained only by remote controlled robots.
As for He3, yes it is a potential power source - once we have a fully working fusion reactor, but then you first have to build that reactor on the Moon.
Trillions of investment over probably at least 2 decades could be needed before the first space vehicle was produced.

I was envisioning a process something like building the space station. Sub-assemblies are manufactured on earth, then lifted into orbit and fitted to the growing station. The same thing would be done with the moon in place of an orbiting station. But then, I haven't done the numbers and whichever way it's done, it will be a complex, lengthy and expensive enterprise to colonize either the moon or mars. In either case though, a solution to the radiation problem must be found and taking advantage of natural underground shelters would be one way to accomplish this.