Terraforming Other Planets?

[Turtle]

somethings on planets & atmospheres. :moon:

 

Planetary Science

...Escape of an Atmosphere

The thickness of a planet's atmosphere depends on the planet's gravity and the temperature of the atmosphere. A planet with weaker gravity does not have as strong a hold on the molecules that make up its atmosphere as a planet with stronger gravity. The gas molecules will be more likely to escape the planet's gravity. If the atmosphere is cool enough, then the gas molecules will not be moving fast enough to escape the planet's gravity. But how strong is ``strong enough'' and how cool is ``cool enough'' to hold onto an atmosphere? To answer that you need to consider a planet's escape velocity and how the molecule speeds depend on the temperature.

...

Does Gravity Win or Temperature?

 

...

The effects of gravity and temperature work opposite to each other. A higher temperature tries to dissipate an atmosphere while higher gravity tries to retain an atmosphere. If the particle's average speed is close to the escape velocity, then those type of gas particles will not remain for billions of years. The general rule is: if the average gas molecule speed for a type of gas is less than than 0.2×(the escape velocity), then more than 1/2 of that type of gas will be left after one billion years. If the average speed is greater than that critical value, then more than 1/2 of that type of gas will be gone after one billion years. A flowchart of this is given on the escaping atmosphere page.

...

Atmosphere Escape via Non-Thermal Processes

...

If a planet does not have a magnetic field (for reasons described later), the solar wind can strip an atmosphere through a process called sputtering. Without a magnetic field, the solar wind is able to hit the planet's atmosphere directly. The high-energy solar wind ions can accelerate atmosphere particles at high altitudes to great enough speeds to escape. An additional way of atmosphere escape called photodissociation occurs when high-energy sunlight (e.g., ultraviolet or x-rays) hits high-altitude molecules in the planet's atmosphere and breaks them apart into individual atoms or smaller molecules. These smaller particles have the same temperature as the larger molecules and, therefore, as described above, will move at faster speeds, possibly fast enough to escape. ...

 

note that a magnetic field is not necessary to form an atmosphere; it only slows, slightly, an atmosphere's escape. here's what i found on the evidence for the formation history of earth's atmosphere; note it predates the formation of our magnetic field.

 

Remote Sensing Tutorial Page 19-2a

 

age of earth's magnetic field;3.5 billion years Earth's magnetic field - Wikipedia, the free encyclopedia

 

/forums/images/smilies/banana_sign.gif

[Eclipse Now]

OK thanks for that Turtle. So I take it from the discussion above that:

 

* solar wind won't blow away a Martian atmosphere significantly fast enough to worry about if we already have the technology to terraform Mars in the first place? (And that assumes the technology to throw ice asteroids into the Martian atmosphere).

 

Does the solar wind 'slow' or merely have 'less per meter square' effect by the time it gets to Mars?

 

* Radiation isn't a problem with a thick enough atmosphere? (I'm sure I read that it was on the terraforming Mars wiki: although on a second reading I may be overstating the case).

 

The lack of a protective magnetic field would also have possible health effects on colonists due to increased cosmic ray flux. The health threat depends on the flux, energy spectrum, and nuclear composition of the rays. The flux and energy spectrum depend on a variety of factors, which are incompletely understood. The Mars Radiation Environment Experiment (MARIE) was launched in 2001 in order to collect more data. Estimates are that humans unshielded in interplanetary space would receive annually roughly 400 to 900 milli-Sieverts (mSv) (compared to 2.4 mSv on Earth) and that a Mars mission (12 months in flight and 18 months on Mars) might expose shielded astronauts to ~500 to 1000 mSv.[17] These doses approach the 1 to 4 Sv career limits advised by the National Council on Radiation Protection and Measurements for Low Earth orbit activities.

 

Terraforming of Mars - Wikipedia, the free encyclopedia

[Turtle]

OK thanks for that Turtle. So I take it from the discussion above that:

...

Does the solar wind 'slow' or merely have 'less per meter square' effect by the time it gets to Mars?

 

does that "or" just indicate a rephrase of a single idea, or do you mean it to separate alternative ideas? anyways, solar winds are neither continuous nor constant in speed or density, but the particles for the most part do obey an exponential decay phase. ... or so i heard. >> SpringerLink - Journal Article

[Eclipse Now]

I checked the link and got a headache. Too technical looking.

 

Basically, I was just checking I had your posts right... How much of a problem would atmospheric leak be on Mars? Would Martian descendants eventually end up building a giant 'window' of some sort to place in front of Mars and prevent the solar wind blowing off atmosphere? (Whether that window is plasma / biogel / carbon-nano-tube diamond / self-healing clear composites or whatever is not the issue just now. We'll just assume that it stops the solar wind but lets sunlight through).

[Turtle]

I checked the link and got a headache. Too technical looking.

 

Basically, I was just checking I had your posts right... How much of a problem would atmospheric leak be on Mars? Would Martian descendants eventually end up building a giant 'window' of some sort to place in front of Mars and prevent the solar wind blowing off atmosphere? (Whether that window is plasma / biogel / carbon-nano-tube diamond / self-healing clear composites or whatever is not the issue just now. We'll just assume that it stops the solar wind but lets sunlight through).

 

"how much a problem" depends on all the specifics we don't have: what gasses do we have? in what proportions? what temperatures? how much open water? yada, yada, yada...too technical to who laid the pooch. :lol: no giant window. you just need to keep the mars atmosphere renewed at a rate that cancels the escape. plants. lots of 'em. :moon: ;) :ip: :ip: also, you need an atmosphere to get water to exist on the surface i just read. then, there is the matter of a warmer atmosphere escapes faster, so you gotta cancel that too as the greenhouse effect kicks in. forget the magnetic field & forget the solar wind; they are inconsequential.

[TheBigDog]

I understand Eclogite's arguments, however I cannot simply ignore published science on his objections alone. Here are several sources that state the magnetosphere protects the earth from radiation, including solar wind as a form of radiation.

 

If the magnetosphere protects the atmosphere, and the atmosphere protects from radiation then you still need the magnetosphere first. The charged solar wind will otherwise strip away the atmosphere where it is vulnerable to that affect.

 

Here are some links...

 

The Earth's Magnetic Field

 

Earth's Magnetic Field

 

Magnetosphere - Wikipedia, the free encyclopedia

 

Bill

[Eclipse Now]

Hi Big Dog,

3 points:

* What about the first billion years of our atmosphere as highlighted by Turtle?

* Those papers are about Earth. What strength is the solar wind at Mars?

* Mars is a lot smaller than Earth so maybe the lower solar wind velocity and strength at Mars is not that offset because there's less gravity to glue the atmosphere to Mars anyway!?

[TheBigDog]

Hi Big Dog,

3 points:

* What about the first billion years of our atmosphere as highlighted by Turtle?

* Those papers are about Earth. What strength is the solar wind at Mars?

* Mars is a lot smaller than Earth so maybe the lower solar wind velocity and strength at Mars is not that offset because there's less gravity to glue the atmosphere to Mars anyway!?

The first billion years of atmosphere are highly speculative. If much of our atmosphere came from collisions with bodies from space like comets then during the first billion years it was a time that the components for the atmosphere were building, probably faster than they were being swept away.

 

I don't know the strength of the solar wind here or on mars. The papers state that the lack of a thick atmosphere on Mars is in part caused by the lack of a magnetic field. Because Mars is so much less massive than the earth its core cooled more quickly, stopping the dynamic forces that generated its magnetic field in its younger days. When that stopped its atmosphere was mostly swept away.

 

The solar wind has the same velocity at Mars. What would slow it down? It is less dense because it has traveled farther from the sun. Inverse square of the distance from the source (I think).

 

Without a magnetic field adding atmosphere to Mars would be futile. A portion of your efforts would simply be blown away. Even if it blows away slower than you generate it, you still need to generate it constantly to maintain it. This means mass on a grand scale. Where is all of this mass coming from? Where is the energy for delivering the mass to mars coming from?

 

I think that Mars makes a terrible candidate for tera forming. Our problem is that it is our best candidate in our solar system, so we cling to the hope and dream of greening the red planet. It just won't happen. There may be enclosed settlements some day, but we will not build an atmosphere on that rock to support life. We need to find candidates that are ripe, not dried out. We need a grape not a raisin.

 

Bill

[belovelife]

 

I am sure at some point we can do this but eventually the atmosphere would have to capture the required amount of heat in it's own.

 

 

 

Worms might survive after many thousands of years of lichen growth establishes organic soil...

 

 

 

I'm not sure why we would want to do this but I see no reason why not.

 

-----------

Well If for instance we were to find intelligent life elsewhere

we could use the large brains of marine life to communicate

 

as far as living in space

I agree artificial gravty is the way

but we would probly need to make a mini black hole

to get gravity on a space ship we are used to

either that or make a moon sized space ship with mainly heavy metals at the core

but inthink the mini black hole would be possible, but difficult to maintain

 

 

So you are talking about living in zero gee? I would prefer artificial gravity, it would keep us healthier in the long run and more human..

 

 

 

 

I'm not sure why we would want to do this either, can you elaborate?

[Eclipse Now]

Without a magnetic field adding atmosphere to Mars would be futile. A portion of your efforts would simply be blown away. Even if it blows away slower than you generate it, you still need to generate it constantly to maintain it. This means mass on a grand scale. Where is all of this mass coming from? Where is the energy for delivering the mass to mars coming from?

 

Is there uranium or plutonium out in the Asteroid Belt? If we built an O'Neil colony that had plenty of uranium in Integral Fast Reactors, we wouldn't need new energy to the O'Neil colony for centuries. It could just float around the Asteroid Belt collecting both metal and watery asteroids and converting them into rockets and fuel. Then it could fire them in towards Mars, with an explosion in the upper atmosphere.

 

Now if the solar wind proved it actually was a problem, then we could build a big 'magnifying glass' in space. It could both stop the solar wind and warm the planet. Unless I am mistaken, there was something like this in the Kim Stanley Robinson series.

 

I think that Mars makes a terrible candidate for tera forming. Our problem is that it is our best candidate in our solar system, so we cling to the hope and dream of greening the red planet. It just won't happen. There may be enclosed settlements some day, but we will not build an atmosphere on that rock to support life. We need to find candidates that are ripe, not dried out. We need a grape not a raisin.

Bill

Why is it either / or? We could settle Mars in underground colonies, which could then also begin the terra-forming. This would preclude more radical 'comet smashing' terraforming projects, but those seem to take too long anyway.

[modest]

somethings on planets & atmospheres. :moon:

 

Planetary Science

...If the average speed is greater than that critical value, then more than 1/2 of that type of gas will be gone after one billion years. A flowchart of this is given on the escaping atmosphere page.

...

 

That is a very good source. The flowchart is all we need except that the formula in the flowchart,

annoyingly says 'constant' rather than giving the constant. By looking up escape velocity and kinetic temperature, it should nonetheless be clear that the constant on the left is 'G' and the constant on the right is 'k'.

 

Following the flowchart for Mars at 20 C gives the following for oxygen:

 

G = grav. constant = 6.67 x 10^-11 N(m/kg)²

M_m = mass mars = 6.42 x 10²³ kg

r = radius mars = 3 389 500 meters

k = Boltzmann constant = 1.380 x 10^-23 J/K

M_O particle mass of oxygen = 2.657 x 10^-26 Kg

T = 293.15 kelvin

 

The average speed of an oxygen molecule on a terraformed mars is:

[math]V = \sqrt{\frac{3kT}{M_O}} = 675.8 \ m/s[/math]

The escape velocity for a particle on mars is:

[math]EV = \sqrt{\frac{2GM_m}{r}} = 5026.6 \ m/s[/math]

 

Therefore, the average speed of a particle of oxygen on mars with a temperature of 20° C is only 13.4% of the escape velocity needed for it to 'leak' off the surface. According to the flowchart, if the % is less than 20% (which it is) then less than half of that gas would be gone after 1 billion years of the planet's evolution.

 

As Turtle's source says, solar wind would add to the rate of stripping, but I don't know any formula to calculate specifically by how much the rate would increase. Since 13.4% is close to 20%, I would guess that it would easily be enough to make up the difference for the purposes of this flowchart. I would guess that a billion years would be enough to strip Mars of most of its oxygen, but without a precise formula for the effect of the solar wind, I don't know how we could say for sure.

 

Nonetheless, it could be argued that having the technology necessary to create an atmosphere on mars in the first place would mean that one could easily keep it sustained by the same technology. It is harder to fill a leaky bucket than it is to keep it full.

 

~modest

[Eclipse Now]

Wow Modest, that's the kind of equation's you do for fun?:moon: My brain was full just reading the first line!

Nonetheless, it could be argued that having the technology necessary to create an atmosphere on mars in the first place would mean that one could easily keep it sustained by the same technology. It is harder to fill a leaky bucket than it is to keep it full.

~modest

One terraforming Mars fan-site I read talked about building a glass roof over the planet on 1km high pylons! :eek_big::hyper::P:eek:

 

Umm, meteorites? Cost? Etc....

 

But maybe, as you say, if they can terraform it in the first place who knows what technologies they might have by then?

 

Would they have some self-healing, lighter than air 'membrane' that can float about at a certain height, let meteorites in and then self-heal to keep the atmosphere from leaking out? Or would this membrane indeed be built on huge carbon-nanotube stilt's 10km high, nicely reducing both the amount of atmosphere we needed to create and preventing leakage? We're talking about the technology our grandchildren may one day own. It might not even be that far away. It's the exponential nature of progress. Tiny changes here allow advances over there, and accumulating all together they add up to significant advances.

[modest]

I'm not sure a membrane would be needed.

 

I think you had the idea of giving Mars an atmosphere by hitting it with comets. If we could do that then the atmosphere could be likewise sustained against leaking by hitting the planet with a few comets from time to time. Assuming we can terraform the planet in the first place, then the same terraforming technique should be able to sustain it against leaking.

 

~modest

[Eclipse Now]

hitting it with comets.

 

I prefer the term 'high atmospheric air-burst' compared to 'hitting it with comets', as I'm hoping there are already settlements there by this time. But otherwise I think we're on the same page.

 

(Unless they really can come up with a membrane!:P)

[Moontanman]

Colonizing Mars would be much harder than colonizing Antarctica and i don't see anyone standing in line to live there. Living in under ground bunkers isn't exactly a prime selling point for colonization. Terra forming would take longer than the existence of our current civilization. Artificial space habitats still win hands down....

[Eclipse Now]

Colonizing Mars would be much harder than colonizing Antarctica and i don't see anyone standing in line to live there.

 

I'm really tired of hearing this argument. Antarctica does have a colony, that does the job (of studying Antarctic wildlife, climate change, etc). But living in Antarctica doesn't grab the imagination the way Mars does. Again, the job of the Mars colony is to grow. The job of the Antarctic base is to study. There are people willing to dedicate their lives to living on Mars and growing a society that are not at all motivated by Antarctica in the same way.

Newsflash: Antarctica is on our planet. The argument is to see if we can live on another world, not whether we can build a big, expensive base in the coldest wilderness on this world. We could, if we wanted to, grow the bases that are already there in Antarctica. But because there is already a base there showing us all the pictures we could possibly want of Penguins in Antarctica, we don't want to. But show me pictures of Penguins on Mars? I'd be willing to contribute a few tax dollars towards that!

 

The job of a colony on Mars is simply being there, off world, as a backup for the human race, and gradually growing in size and numbers. And one day even reaching the potential to grow ecosystems on the surface.

 

Underground malls are quite nice places. We have them in Sydney. With a few gardens etc I could imagine a whole civilisation growing underground. Fred Hapgood has already written about some cities where real estate underground is proving to be cheaper than on the surface, and visualises the first residents who will one day live underground fairly permanently.

 

But back to the point: Mars is a whole planet full of materials to build on. A few dozen rockets to Mars could hypothetically create our first off-world town. Then it would be over to the locals to continue to expand their habitats all constructed from local materials.

 

How are you going to build the first space colony? How many rockets would that take? Mind you, I love the idea of an O'Neil colony but wonder if that's harder initially to do? How many payloads is it to construct it and launch all the materials into space? Compare this to how many payloads to get enough people, food, and energy systems to Mars and then use local materials to build out the rest of the permanent habitat! I bet you we're talking orders of magnitude less rockets to achieve the same end: an off-world village.

 

Mission Statement

 

The mission of the Mars Homestead Project is to design, fund, build and operate the first permanent settlement on Mars.

 

The initial goal for the Mars Homestead Project is to identify the core technologies needed for an economical, growing Mars Base built primarily with local materials. Efforts will then be focused on prototype projects of increasing sophistication. These could include the selection of existing equipment which could be used on Mars, or the construction of prototypes of new equipment. These steps will lead the Mars Foundation to the establishment of an entire simulated Mars settlement at a location here on Earth, which will serve as a research and outreach center.

 

The initial programming feasibility study has been conducted by a small Program Team, whose members have professional or academic experience in applicable engineering areas. Areas of expertise include: Materials, Structures, Mechanical Systems, Architecture, Agriculture, Nutrition, Process/PSSS, Electrical Systems, I&C, Data/Telecom, EHS, IE, Mars Geology/Topography, Space Transportation, Spacesuits, Systems Integration, and many others.

 

The Mars Foundation has also established a small board of technical advisors who provide expertise in specific areas, and created a general "brainstorming" discussion group which is open to the interested public, regardless of their technical experience.

 

Some locally derived materials have been examined for initial settlement construction. These materials include locally produced fiberglass - wound on site, metals, masonry - either for un-pressurized shelter or covered with regolith to hold the pressure, polyethylene & other polymers made from ethylene from the CO2 atmosphere, and any plant products - especially if a byproduct of food growth. The MHP team continues to evaluate these options as well as a number of potential alternatives.

The Mars Homestead Project | About Us

 

Caveat for O'Neil space colony:

If we develop powerful enough AI, robotics, and self-replicating spacecraft that we can launch at the asteroid field, then maybe one day we'll just shoot one rocket at the asteroid field and a generation later a whole shiny new O'Neil colony will fly back to Earth to rendezvous with passengers. But that seems to be a long way off.

 

The various Mars societies have plans for a settlement there, we have GenIV reactors that require very little fuel to provide all the power they'd need, and they have the people willing to go. And we have all that today.

[Moontanman]

While i agree with the mystical aspects of what you are saying i see no reason why the same rockets to the Lagrange points of Jupiter couldn't result in the first of many torus type colonies made of carbon fibers and dreams. Sometimes i think my absolute love of John Varleys novels Titan, Wizard, and Demon has colored my judgment on this but once you see the vistas imagined by John Varley he projects into your mind it's difficult to accept living huddled under ground in tiny places.....

 

I also see no reason it would take some kind of mystical nano tech for this to happen, unless working in zero gee some how messes with robots and remote control i see no reason why humans couldn't go and direct the building of these things, living in small spinning ships to imitate gravity with the occasional space walk i can see this with out the Von Neumann type machines...

 

http://en.wikipedia.org/wiki/Self-replicating_spacecraft