Why colonize Mars and not the Moon?

[ProfChuck]

When it comes to colonization I think we are getting a bit ahead of ourselves. Outposts on both the Moon and Mars will be necessary before we can evaluate the practicality of colonization. I think that both lunar and martian occupancy will be driven by activities like asteroid mining and resource refinement. Constructing robotic mining and manufacturing systems on both the Moon and Mars is a reasonable next step. In my opinion as a scientist in the space program for over 40 years and as a consultant for an asteroid mining company, human occupancy will follow only if it becomes an essential part of the program.

 

[Xiaochao Zheng]

Wow, 23 pages of replies. I am certainly late in joining this topic.

Now, we are talking about the reasons based on physics, right? The sun will become a red giant at some point, and at that time Earth will be engulfed by the expanding sun (recall superman's mother planet? same will happen to us). The moon will not survive the red giant either.

And even long before that, there is an argument that the solar energy will increase by 10% and by that time, again, Earth will be too hot for water to remain liquid. And again, Mars will be in the new habitable zone.

That's just two main reasons why Mars is a better colony than the Moon. However, one could argue that the human species will wipe ourselves out long before these events happen.

 

[pkt]

"The scientific progress from a Mars colonization would be massive."

Nobody drinks Tang or cooks on Teflon.

 

[Al_]

Constructing robotic mining and manufacturing systems on both the Moon and Mars is a reasonable next step. Human occupancy will follow if it becomes an essential part of the program.

Robotic mining is a lot easier on the Moon due mainly to the much shorter latency for comms.
I think human occupancy will follow not entirely as an essential part of the program. It will be very much more productive to control the robots from close by to give a more real-time feel to telepresence. And it will be a lot of fun to be on the Moon or Mars. And it will probably offer wonderful opportunities for both private enterprise and career progression.

 

[mfb]

Outposts on both the Moon and Mars will be necessary before we can evaluate the practicality of colonization.

Please give a reference for the claim that a lunar outpost will be necessary.

 

[ProfChuck]

Please give a reference for the claim that a lunar outpost will be necessary.

This is my opinion based on my work on the space program for over 40 years.The necessity of a lunar outpost will be dictated by economic considerations. Resource exploitation of both lunar and Martian raw materials and the development of autonomous systems will determine if human presence is necessary.

 

[Al_]

That's just two main reasons why Mars is a better colony than the Moon.

Sorry, that does not follow at all.
The end of the Earth due to an expanding Sun is an extremely long time away, and the end of Mars is comparatively soon after. By then we will need to be outside the inner planets completely. The Moon lies on the quickest route out. If we have to leave completely, getting out of one gravity well, why get stuck down another one?
The warming of Mars due to an increase of the Sun's radiation is a very long time away too. If we haven't gone into space before then it's a poor show.

 

[mfb]

This is my opinion based on my work on the space program for over 40 years.

Then write it as opinion please, not as fact.

 

[ProfChuck]

Robotic mining is a lot easier on the Moon due mainly to the much shorter latency for comms.
I think human occupancy will follow not entirely as an essential part of the program. It will be very much more productive to control the robots from close by to give a more real-time feel to telepresence. And it will be a lot of fun to be on the Moon or Mars. And it will probably offer wonderful opportunities for both private enterprise and career progression.

I worked for NASA for over forty years and am now consulting with several companies that are exploring the potential of asteroid mining and antimatter propulsion systems. I have been criticized for expressing my opinion and not identifying it as such. The following is my opinion based on many years of work in the field of spacecraft systems design, astronomy and astrophysics.

The moon is attractive for several reasons. The absence of an atmosphere and the low gravity makes magnetic launcher systems practical for delivery of refined materials and manufactured goods. This would mean a significant reduction in rocket fuel and reaction mass for delivery systems. The far side of the Moon may be an ideal location for large radio and optical telescopes. The mass of the Moon would provide shielding from light and electromagnetic "noise" that originated on the Earth. Large scale scientific experiments requiring hard vacuum and radiation can be performed on the Moon they could not accommodated on the space station. However, it is the applications that we have not yet thought of that will probably dominate the activities on a lunar outpost.

 

[mheslep]

...

The moon is attractive for several reasons. The absence of an atmosphere and the low gravity makes magnetic launcher systems practical for delivery of refined materials and manufactured goods. This would mean a significant reduction in rocket fuel and reaction mass for delivery systems. The far side of the Moon may be an ideal location for large radio and optical telescopes. The mass of the Moon would provide shielding from light and electromagnetic "noise" that originated on the Earth. Large scale scientific experiments requiring hard vacuum and radiation can be performed on the Moon they could not accommodated on the space station. However, it is the applications that we have not yet thought of that will probably dominate the activities on a lunar outpost.

Assuming all of this is correct, why is any of this Moon activity necessary for manned Mars missions, or a more permanent Mars presence?

Moon outposts have been proposed to support space based construction of large vehicles for Mars trips, e.g. in NASA's 1990 SEI, 90Day Report costing $500B with a 20 to 30 year schedule. However, the assertion that assist from the Moon is a cheaper route than launching direct to Mars from Earth has been fairly well debunked by the far less expensive Mars Direct plan (more than ten times less expensive than the 1990 mission plan ). Even NASA's subsequent Moon free Mars Design Reference is far cheaper than a Moon linked mission.

https://www.nasa.gov/pdf/376589main_04%2520-%2520Mars%2520Direct%2520Power%2520Point-7-30-09.pdf

 

[ProfChuck]

WRT "Assuming all of this is correct, why is any of this Moon activity necessary for manned Mars missions, or a more permanent Mars presence? "

Reference https://www.physicsforums.com/threads/why-colonize-mars-and-not-the-moon.899537/page-24
I don't think it is. Lunar and Martian exploration and exploitation activities should be viewed in terms of economics if they are to be successful in the long run. There are lessons that can be learned on the Moon that will be useful on Mars but that is not necessarily the only way to learn them. If the Moon can be a source of economically valuable commodities and services then a machine and human presence will be justified. The same is true of Mars. Otherwise colonization must be viewed as a philanthropic activity rather than a scientifically or commercially valuable one. If someone with deep pockets is willing to fund such an operation I see no reason why they should not do so.

 

[mfb]

In the short run, every step towards Mars or Moon will cost more than it can give economic benefits. In the long run, it can look different. The question is how long does it need. Something that gives profit in 5-10 years gets commercial funding. Something that gives profits in 30+ years does not.

Even NASA's subsequent Moon free Mars Design Reference is far cheaper than a Moon linked mission.

Now imagine that but with reusable rockets, from a company that has a proven record of developing rockets a factor 10 cheaper and launching them significantly cheaper than NASA (although just with 1 data point) - and those numbers are still without reuse.

 

[ProfChuck]

In the short run, every step towards Mars or Moon will cost more than it can give economic benefits. In the long run, it can look different. The question is how long does it need. Something that gives profit in 5-10 years gets commercial funding. Something that gives profits in 30+ years does not.Now imagine that but with reusable rockets, from a company that has a proven record of developing rockets a factor 10 cheaper than NASA (although just with 1 data point).

The asteroid mining people I am working with expect an ROI within 20 years. It's a long shot but the potential payoff is enormous. The antimatter propulsion people expect an ROI within 5 years with microsatellites being their first application. I hope they are right. You are correct about reusable rockets. That will be a real game changer.

 

[JED777]

Planet Mars has an atmosphere that can be "seeded" to create, over time, an atmosphere very similar to Earth's. Not so for the Moon. Then there is the Moon's lack of substantial gravity. We would have rapid muscular and other biological atrophy in short order, as humans do on lengthy space station visits. The Moon's gravity is also not consistent around its surface. An acquaintance of mine, Apollo 15 astronaut Al Worden, discovered this as the science officer on that mission. The side of the moon that faces Earth was bombarded with large meteors, containing heavy metals, billions of years ago,. The far side has mostly very small craters, thus there is less gravity on that side. He discovered this when waking up from a snooze, as the solo Command Module pilot/science officer, while Astronauts Irwin and Scott were on the surface. The Command Module had lost altitude dramatically while he was sleeping, and was under 700 feet above approaching mountain peaks. Mission control called to warn him right about this time. They too did not expect this to happen. Worden was assigned an orbit lower than any previous mission. Plus the moon would be plain old boring! Yes, indeed Mars seems to be the ticket. I'll take 4 tickets please! Two human 2 Canine. :)

 

[lifeonmercury]

Then there is the Moon's lack of substantial gravity. We would have rapid muscular and other biological atrophy in short order, as humans do on lengthy space station visits.

Very interesting post and I like that enthusiasm! What is your assessment of the effect that Martian gravity (38%) would have on humans living there?

 

[mfb]

We would have rapid muscular and other biological atrophy in short order, as humans do on lengthy space station visits.

We do not know that. We know zero gravity is problematic, we know 1 g is fine, and we don't have any data in between.

The Moon's gravity is also not consistent around its surface.

Yes, but the deviations are small. Local gravitational acceleration varies on Earth as well.

The Command Module had lost altitude dramatically while he was sleeping, and was under 700 feet above approaching mountain peaks.

@JED777: Please give a reference for that claim. I don't find anything about problems of the CM, and such a close encounter would certainly have been reported. The lowest point of the orbit was at 14.1 km, a bit lower than planned, when they raised it to 17.8 km, closer to the plan. The highest point of Moon is 10.8 km above the reference level, but that is just a single point. By far less dramatic than "700 ft" would suggest. In addition, that happened while all three astronauts were still on board.

 

[Al_]

However, the assertion that assist from the Moon is a cheaper route than launching direct to Mars from Earth has been fairly well debunked by the far less expensive Mars Direct plan (more than ten times less expensive than the 1990 mission plan ). Even NASA's subsequent Moon free Mars Design Reference is far cheaper than a Moon linked mission.

I would like to make a distinction betwen two different things.
The first is a Mars mission that involves the Moon as a part-way stage, perhaps a place to pick up resources or learn skills.
The second is a Mars mision that is launched entirely from the Moon, by a theoretical future spacefaring colony.
The second might cost Earth nothing at all, and likely to be much easier for the Lunar colony to do than for any Earth-based attempt, since (apart from the delta-vee advantage) we are assuming a successful set of technologies already affordable and familiar to the Moon colonists, and lunar resources already found and developed.

 

[Al_]

Planet Mars has an atmosphere that can be "seeded" to create, over time, an atmosphere very similar to Earth's.

I find this very surprising. Can you provide some references please?
Even if this is possible, it is so far in the future that it is not relevant to this thread, which is about colonisation, not terraforming.

Plus the moon would be plain old boring!

Really, are you serious? An entire, huge, other world?
Mars has the advantage of some pretty landscapes. That's about it for entertainment. How long before that gets boring? That's a a long way extra to go for some good selfies.

 

[mfb]

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.

 

[ProfChuck]

While the Moon may not be a practical location for a colony it could be a significant industrial base. The absence of an atmosphere and low gravity make access to space much easier. As mentioned before magnetic launchers are practical on the moon so rocket fuel consumption is significantly reduced. Mars colonies are easier but still difficult. With any current or envisioned technologies "open air" facilities are not possible. Terraforming the Martian atmosphere poses some significant problems because the low gravity makes atmosphere retention a major challenge. I suspect that human participation in lunar and Martian facilities will be part of an entirely new space based economic system that is driven by access to enormous quantities of raw materials.

 

[rootone]

Which raw materials that cannot be found at all on Earth though?

 

[ProfChuck]

Construction of large space based systems such as O'Nieill colonies or asteroid mining processing facilities will require huge quantities of raw materials. While these materials are available on the Earth launching them into space is enormously costly. It will be much cheaper to mine on the moon and deliver materials to space. Colonization will be the result of a new space based economy. I predict that there will be major drivers to ultimately establish outposts and colonies throughout the Solar system including on Mars.

 

[nikkkom]

Terraforming the Martian atmosphere poses some significant problems because the low gravity makes atmosphere retention a major challenge.

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

 

[nikkkom]

The antimatter propulsion people expect an ROI within 5 years with microsatellites being their first application.

What are you talking about? What kind of antimatter?

 

[ProfChuck]

What are you talking about? What kind of antimatter?

Synthetic radio isotopes that emit positrons. Very similar to that used in medical PET scan systems.

 

[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.