# Featured Why colonize Mars and not the Moon?

1. Jan 7, 2017

### lifeonmercury

I watched the 6-episode series called Mars this week. Elon Musk kept emphasizing that humans must spread out to at least one other planet to ensure human survival in the event of some extinction event on Earth.
Wouldn't colonization of the Moon achieve the same purpose? Seems like that would be a more viable option.

2. Jan 7, 2017

### phyzguy

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.

3. Jan 7, 2017

### Staff: Mentor

Mars has carbon, hydrogen, oxygen, and probably nitrogen available, several metals are available, and various other elements can be found in smaller amounts. The moon has oxygen and a few metals, but everything else is challenging. Mars has a 24 hour day and a higher gravity THAN MOON*. Building a small station on Moon is easier, but for a colony Mars is better.

In terms of extinction: If an asteroid hits Earth, secondary impacts could also hit the Moon. Diseases can spread better between Earth and Moon due to the shorter travel time.

* that should have been obvious from the context, but as I got misunderstood twice, better make it absolutely clear

Last edited: Mar 19, 2017
4. Jan 8, 2017

### PeroK

Colonising Mars or the Moon sounds like pure fantasy to me. What extinction event on Earth could possibly make life on Earth less tenable than life on Mars or the Moon? If the worst comes to the worst we're better having a few people living in a bunker on Earth than a bunker on Mars.

5. Jan 8, 2017

### Staff: Mentor

A really big asteroid impact. Bunkers don't work forever, and their tolerance for seismic waves is limited as well.

A virus maybe, natural or artificial, if it spreads fast enough without obvious warning signs.

6. Jan 8, 2017

### PeroK

If bunkers don't work forever on Earth, they won't work forever on Mars. The Earth, even after an asteroid impact, would be a paradise compared to Mars, where there is absolutely nothing to sustain human life.

Instead of going to Mars, you could put many secure colonies here on Earth.

And, if the Vogons came to destroy the Earth, they would no doubt turn their death ray on our Martian colony as well!

7. Jan 8, 2017

### Staff: Mentor

They don't have to, because Mars didn't have a massive impact in this scenario: you can use solar energy, for example. Not just for electricity - most of our indirect power consumption is used to produce food.
Not at the moment. That is exactly what colonization would change.
No one claimed it would help against an alien invasion.

8. Jan 8, 2017

### PeroK

I can't see that building a series of secure habitations across the planet: power sources, food and water supplies etc. is more infeasible/impractical than building a similar colony on Mars.

As I see it, IF we had the technological capability of building and maintaining a Martian colony, we would certainly have the technological capability to build a secure colony on Earth that overall had a much greater chance of long-term survival.

Getting, say, 100,000 people safe on Earth must be more practical than getting a sustainable existence for 100,000 on Mars.

Eventually, if we had the technology to transform Mars into a habitable planet, it might be different. But, any Martian settlement in the foreseeable future would be on the edge of existence and almost certainly dependent on Earth.

9. Jan 8, 2017

### Staff: Mentor

Getting completely independent of solar energy? We don't know how to do that yet.
Anyway, a lot of R&D for those two options would be shared.

Who would build a massive completely independent and isolated underground colony on Earth? With no contact without months of quarantine to avoid any infection spreading? On Mars you can explore a new world, maybe even terraform it over very long timescales.

Making extinction less likely is a nice feature of a Mars colony, but it is not the only argument. I would say it is not even the most important element.

10. Jan 8, 2017

Given the choice between such a colony on Earth and a life on Mars, I know which one I would choose. Also, what could be achieved on Earth in, say, 10 years with $10 billion dollars would take centuries and an unimaginable budget for Mars. The secure Earth settlements could be built before we even had a viable shuttle to Mars. Very long term is different, But, as I see it, for the next century or so, we are earthbound. 11. Jan 8, 2017 ### russ_watters ### Staff: Mentor I agree that there are no good reasons to put a colony on either Mars or the Moon, however if we accept the starting premise that we should explore Mars, then an exploration mission practically has to be a colonization mission due to its distance from Earth. 12. Jan 8, 2017 ### mfb ### Staff: Mentor There are perfectly viable mission sketches for two-way trips with a few months on Mars. A colony would allow much better exploration of course. One has the sole purpose of making extinction less likely (but still possible), the other one is actually doing something new. The scientific progress from a Mars colonization would be massive. Without trying something new, we would still be in the stone age. A completely independent underground Earth-based colony in 10 years? Construction time alone would exceed that. We had attempts to make that work on a small scale using sunlight - so far, no system was completely independent, the food/oxygen/CO2 balance didn't work. Now add the need for an independent power source - which means the technology to run a sizable nuclear reactor for decades. We might have that shuttle in 10 years. SpaceX is building components of such a shuttle already. The very long term would be for terraforming attempts. I don't see a reason why we should be earthbound for the whole 21st century. 100 years is a really long timespan. 13. Jan 8, 2017 ### PeroK It is extraordinary to me that if we initiated two projects: Project A: to have somewhere secure on Earth Project B: to establish a colony of Mars Then, somehow, project A runs into all sorts of problems of feasibility and cost (we can't even do "X" yet). But, project B, by contrast, has few additional problems! Let's just take one small example: A) Cost of building and maintaining a major hospital on Earth? B) Cost of building and maintaining a major hospital on Mars? There is no comparison. Building modern medical facilities on Mars is pure fantasy. Building them on Earth in some sort of "secure" area that might survive an asteroid strike is at least possible. And, critically, if that is not possible, then the impossibility of doing it on Mars is all the more apparent! I know a lot of people think that if the Earth gets trashed, we just upsticks to Mars, but I don't see it that way! 14. Jan 8, 2017 ### mfb ### Staff: Mentor I don't say that. Both projects have a lot of common things to figure out. Both have their own unique challenges. A Mars colony will cost much more, but it will also have different funding sources. But those projects don't have the same goal! They are completely different. 15. Jan 8, 2017 ### Potopea Daniel Well,I think that this is linked with the Sun itself. Without atmosphere,both Moon and Mars are vulnerable,but Mars is (at least) farther from the Sun,so it is more protected than the Moon. 16. Jan 8, 2017 ### PeroK I found this, which is quite interesting: http://www.universetoday.com/14883/mars-colonizing/ This guy (Elon Musk) seems to be quite serious about it. My favourite bit is this: "But according to Musk, the most likely scenario (at least for the foreseeable future) would involve an economy based on real estate. With human populations exploding all over Earth, a new destination that offers plenty of room to expand is going to look like a good investment." Okay, so let's say I decide to move to Australia. Cost of a one-way flight, let's say, is$1000. What would a flight to Mars cost? It would have to be in the millions (even if possible).

How Musk believes I could retire to Mars is just unimaginable. Even if you exclude the annual costs of food, power, water, oxygen, how many of the 7 billion of us here on Earth can afford a few million dollars (or tens of millions of dollars) for a flight to Mars? The cost of building a house? And what am I going to do there? I'm just going to be stuck inside on a planet with no oxygen, no food, no nothing.

For example, the current costs of space tourism are about $20 million dollars, according to: https://en.wikipedia.org/wiki/Space_tourism#List_of_flown_space_tourists I don't get this at all. I can't believe what I'm reading and that people are serious about this stuff. 17. Jan 8, 2017 ### mfb ### Staff: Mentor "I want to start Mars colonization. I don't have any money. I'll start multiple companies, become a billionaire, get into the spaceflight industry and spend billions to make it possible" is a bit more than "quite serious". Musk estimates$500,000, potentially as low as \$150,000 (in 2016 dollars) - with the first generation of transport ships.
Yes, because we throw away rockets after each use. How much would the trip to Australia cost if everyone would parachute down and the aircraft crashes into the ocean? A million, probably even more. Re-use makes airplanes 1000 times cheaper, and it can make rockets cheaper by a similar factor.

All those plans are public. You can read them. People are serious about stuff because it is in development right now. It is not a sketch on a drawing pad. They build components already.

18. Jan 8, 2017

### Staff: Mentor

I suppose there is an additional assumption or principle behind my view that a trip should should at least spend as much time at the destination as on the ride there. It isn't necessarily logical/is more of a feeling, but then a lot of this topic is.

One assumption people operate on here is that the "colony" should be self-sufficient. I don't see why that is a necessary feature unless it is to be a "perpetuating the species" colony, which I don't see as necessary either.

19. Jan 8, 2017

### PeroK

It's interesting that Musk can convince people, if that's what he has done, that there is viable real estate on Mars to expand into, with the tacit assumption that there is none on Earth. Yet Australia and Canada - for example - are vast, largely uninhabited regions.

It's also interesting that there can be any discussion about the tenuousness of life on Earth - climate change, energy costs, feeding the population, when we live on a planet with essentially everything we need; yet, we can might consider life on Mars where there is essentially nothing to support human life

20. Jan 8, 2017

### Staff: Mentor

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.