orbital mirrors

dunwich · 2012-09-03 10:43:48

In kim stanley robinson's mars trilogy One of the terraforming techniques that they use is a giant lens that carves (using heat) out a massive cannal between the Northern basin end the hellas basin. Something I always found a bid sketchy nut for fun I've compared the numbres with something from zubrins works:

Zubrin says that by building a 125 km mirror with a mass of 200 000 tons could provide a 5°kelvin temprature rise for anything below 70° this is 20/180's (11%) of the martian surface a total area of 1,59E13m² (greater then the European continent)

But if you can double the temprature by halfening the surface area (a 10° rise for 7.96E12m²) you can actually get a 1280° rise by lowering your focus point to 6.22E10m² (the size of lake huron) or 40 960°K by 1.9E9m² If the reasoning fits then carving a canal wouldn't be all that impossible.

karov · 2012-09-09 04:54:44

http://nextbigfuture.com/2012/09/orbiti … gfuture%29

aerosol, photonically controled , "dusty plasma" optics.

RobertDyck · 2012-09-09 14:50:23

An orbital mirror would be huge to have any effect. To keep mass down, you have to use aluminized plastic film. Still, that's a lot of aluminum, and a lot of plastic. And to survive temperature swings in space, you need a good quality plastic. Fluoropolymers will do the job, but they require fluorine. I've argued for PCTFE for various space applications, it's the most impermeable to gas of any plastic that can withstand the cold of orbital space, or the surface of the Moon or Mars. It's also highly UV durable. It's ideal for an inflated greenhouse, pressurized pup tent, or lining a liquid oxygen tank made of carbon fibre composite. However, we don't need it for this application. Teflon FEP would do nicely. That's fluorinated ethylene propylene. It has the formula [C2F4] co-polymerized with [C3F6O], these monomers alternating in very long chains. We can get 'C' and 'O' from a carbonaceous chondrite asteroid, and both moons of Mars are captured asteroids of that type. They have clay, gypsum, some underground water ice, and tar. But I don't know how common fluorine is. Polyimide is a category of polymer, also very strong but doesn't use fluorine. I found lots of information about the maximum temperature it can handle, but not cold. Could a polyimide do the job?

Aluminum is found in rock. Most rock is alumino-silicate ionicly bonded with sodium, potassium, calcium, or magnesium. The easiest rock to process is a type of feldspar, either anorthite or bytownite. Strong hydrochloric acid will dissolve it, especially if you grind to fines first. This rock can be found in stony asteroid and meteoroids.

The film has to be very thin to keep material to a minimum. That means micrometeoroids will tear through it. You have to constantly repair it. The larger the mirror, the more work to maintain it. And if the mirror is large enough and light enough, it will be pushed by light pressure. It's built exactly the same way as a solar sail, it will be a solar sail. So you have to factor that push into any orbital calculations.

It's far easier to just sublimate all dry ice on Mars. Don't try to vapourize rock. The result will be about 30% as much pressure as Earth, but that's good enough.

Koeng · 2012-09-09 18:57:55

How will we sublimate all the dry ice?

-Koeng

RobertDyck · 2012-09-09 19:18:25

Heat. It'll take a combination of technologies: build chemical factories to produce copious quantities of greenhouse gas, as well as orbital mirrors.

Josh Cryer · 2012-09-10 04:45:50

Large orbital mirrors that can literally melt the regolith and release oxidized oxygen as well. Could be effective. Josh did some calculations before, they seemed pretty convincing. It was in the lost posts though. Maybe he'll do the calculations again.

Koeng · 2012-09-10 08:40:20

I wonder what is the cheapest way to heat the poles...

-Koeng

SpaceNut · 2012-09-10 19:55:58

Technological Requirements for Terraforming Mars

Robert M. Zubrin. Pioneer Astronautics.

Christopher P. McKay. NASA Ames Research Center.

If the orbital mirror scheme is adopted, mirrors with dimension on the order or 100 km radius are required to vaporize the CO2 in the south polar cap. If manufactured of solar sail like material, such mirrors would have a mass on the order of 200,000 tonnes

RobertDyck · 2012-09-10 21:04:04

That was the original paper. A marvelous document, achieving numerical models. However it has one problem: Dr. Chris McKay used CFCs. They were banned on Earth because they destroy ozone. We need an ozone layer to protect against UV. UV converts O2 to ozone, it also destroys ozone back to O2. If left alone, it will achieve an equilibrium so that UV that reaches the surface of Mars is the same as Earth. Assuming partial pressure of O2 is the same. But that only works if you don't actively destroy ozone with CFC. When CFC breaks down it releases chlorine, that destroys a huge quantity of ozone before it gets scrubbed out. The solution is to use PFC and SF6 instead of CFC. PerFluoroCarbon is a group of chemicals: CF4, C2F6, C3F8, C4F10, etc.

Midoshi · 2012-09-11 14:04:03

I would mention here that McKay, along with Margarita Marinova and Hirofumi Hashimoto, redid the calculations using PFCs several years ago. Their study involved measuring the spectra of a few candidate greenhouse gases not previously characterized.

Radiative-convective model of warming Mars with artificial greenhouse gases
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110, E03002, 15 PP., 2005
dx.doi.org/10.1029/2004JE002306

Spezmonsta · 2012-10-23 05:32:20

dunwich wrote:

In kim stanley robinson's mars trilogy One of the terraforming techniques that they use is a giant lens that carves (using heat) out a massive cannal between the Northern basin end the hellas basin. Something I always found a bid sketchy nut for fun I've compared the numbres with something from zubrins works:
Zubrin says that by building a 125 km mirror with a mass of 200 000 tons could provide a 5°kelvin temprature rise for anything below 70° this is 20/180's (11%) of the martian surface a total area of 1,59E13m² (greater then the European continent)
But if you can double the temprature by halfening the surface area (a 10° rise for 7.96E12m²) you can actually get a 1280° rise by lowering your focus point to 6.22E10m² (the size of lake huron) or 40 960°K by 1.9E9m² If the reasoning fits then carving a canal wouldn't be all that impossible.

You can't double the temperature by halving the area, you must decrease the area by a factor of 2^4, or sixteen, all according to the Stefan–Boltzmann law radiance (w/m^2) is 5.67*10^-8 * T^4

Also, Zubrin likely means a cumulative effect of using the mirror to heat the poles in order to release CO2, thereby heating the rest of Mars by the greenhouse effect. A 125km mirror would have little effect on its own, as it would only add about 0.034% more solar heat.

RobertDyck · 2012-10-23 13:40:06

Midoshi wrote:

I would mention here that McKay, along with Margarita Marinova and Hirofumi Hashimoto, redid the calculations using PFCs several years ago. Their study involved measuring the spectra of a few candidate greenhouse gases not previously characterized.
Radiative-convective model of warming Mars with artificial greenhouse gases
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110, E03002, 15 PP., 2005
dx.doi.org/10.1029/2004JE002306

A useful paper, but the abstract says:

Here we present new laboratory measurements of the thermal infrared absorption spectra of seven artificial greenhouse gases (CF4, C2F6, C3F8, SF6, CF3Cl, CF3Br, CF2Cl2) at concentrations from 10−7 up to unity.

Chlorofluorocarbons are chemicals composed of only carbon, chlorine, hydrogen and fluorine. There are different classes, CFCs have the formula CClmF4-m or C2ClmF6-m, where m is nonzero. Now look at the chemicals included in this paper. It inlcudes CF3Cl and CF2Cl2. They have the formula CClmF4-m; with the first 'm' is 1, the second 'm' is 2. These are CFCs.

For completeness the other classes: HCFC includes hydrogen, HFC has hydrogen but no chlorine, bromochlorofluorocarbons (BCFC) has bromine, and bromofluorocarbons (BFC) has bromine but no chlorine. The above CF3Br is a BFC.

The problem with CFC is when they decomose they release free chlorine (Cl). That breaks down a lot of ozone before it gets removed from the upper atmosphere. That's why CFCs were banned, not global warming.

Last edited by RobertDyck (2012-10-24 08:18:00)

Midoshi · 2012-10-23 14:11:39

RobertDyck wrote:

The problem with CFC is when the decomose they release free chlorine (Cl). That breaks down a lot of ozone before it gets removed from the upper atmosphere. That's why CFCs were banned, not global warming.

Yes, and the paper ultimately rejects all the Cl containing species because of the O3 destruction problem. Their recommended mix of greenhouse gases consists of CF4, C2F6, C3F8, and SF6.

RobertDyck · 2012-10-24 09:07:24

Midoshi wrote:

Yes, and the paper ultimately rejects all the Cl containing species because of the O3 destruction problem. Their recommended mix of greenhouse gases consists of CF4, C2F6, C3F8, and SF6.

That would be good, but that's not what the abstract says. I used to purchase all sorts of technical papers, like this one, but currently have very limited income. If you want to give me a free copy, I'll read it.

Void · 2013-03-17 11:06:01

I want to suggest an alternative with the orbital mirrors, where a relatively modest influence of added energy coupled with the injection of a relatively small amount of dust would provide a habitat for cyanobacteria in pockets of water in the polar ice.

This might be supported by:

http://www.newscientist.com/article/mg2 … -mars.html

http://www.accessexcellence.org/WN/SUA1 … old698.php

http://skywalker.cochise.edu/wellerr/st … r/Mars.htm

http://spacescience.spaceref.com/current/event/osu.html

It is not out of the question to augment the existing solar flux during the polar warm seasons, but then UV is an issue. The articles suggest that the organisms can protect themselves from UV at least on Earth. However in the polar night, there could be very little UV. The mirrors would need to be selectively reflective, not reflecting UV. That along with the injection of dust could form a layer of dirt maybe 6 feet below the ice layer, and a reasonable addition of light by mirror reflectance could then make this habitat support a microbial community that might release greenhouse gasses suitable to an additional warming, and maybe even helping the formation of Ozone. Maybe this has been covered elsewhere to a degree. I would simply consider it another tool in the tool kit.

As for existing Martian life, I might suggest using a laser to melt small pockets of polar ice, and then sending down a probe to sample the water produced after a reasonal time period. I am going to guess that the Martian habitat has on it's own produced temporary pockets of water inside the ice during relatively recent times, and that if there were life compairable with Earth life swapped back and fourth, there should be the possibility that something lurks in the ice caps, waiting for the occasional melt of a pocket of water. I don't expect that this would be the first check for life, but perhaps the last before terraformation is implemented.

In fact perhaps a mission could instead consist of a probe with a laser which would drop to a pocket of long lasting ice, and shine the laser downwards, it might be that the spectrum of light reflected upwards would reveal the growth of organisms. I would suppose that a tiny water pocket formed would first have one spectrum, and changes in organics would then alter that spectrum. Perhaps after a change was noticed, the laser would be able to change it's spectrum to one that would evaporate the ice, and an air stream conducted to the evaporation would carry it vapors away, in effect drilling down to the site where organic changes were susspected. Then it would be a simple matter to grab some of the goop for further inspection.

http://www.exploremars.org/msl-picture- … rs-phoenix

I know that I am in the terraforming section, but obviously there will be a lot of resistance to the terraformation of Mars until at least some such testing is done.

Alternately the laser probe thing would be useful to confirm that an added solar flux would produce the microbial growth that is desired. Of course such an experiment could be simulated on Earth first.

Last edited by Void (2013-03-17 11:07:45)

SpaceNut · 2013-03-17 11:22:30

Question is there more of a benefit to the reflected suns energy hitting the lighted side versus the nights side to warming the planet or is there also the secondary reason for this is the first place.....

Void · 2013-03-17 21:43:44

A very good question. Well the night side would have very little UV flux, if the mirror's reflection excluded that part of the spectrum. Also, I guess it might be a question also of scale. If you were just going to do a relatively small patch, you could not affect the CO2 condensation very much, but if you kept the surface of the ice above the condensation point of C02 that would make a difference. Of course the CO2 could still condense in the extended caps at lower lattitudes, but that evaporates seasonal to a greater degree than does the stuff at the higher lattitudes, I think, at least at the south pole.

But the main reason for the process would be to generater a layer of water pockets above freezing below the ice. And organisms growing in that would have a growth budget, and fighting damage from UV, or generating protective coatings takes away from that budget.

Is this the best tool? I really don't know. Time will tell. It depends on how humanity comes at Mars. If they are spacefaring and are mining small Earth crossing and Mars crossing asteroids, then they should have the technology and budget for some mirrors I would think.

Dumping dirt on the caps would go hand and hand with this one I would think, since with the propper heating, the dirt should sink into the ice and be able to form a layer insulated by a nominal 6' of ice?

Sort of an ideal actually since you can have a biosphere below, and ward off CO2 condensate above.

−78.5 °C ,−109.3 °F, 194.7 K

So, also a layer of ice say 12 feet thick also is a thermal reservoir, it would continue to release heat for a time when the mirrors were not convenient to add heat.

However it is also reasonable to shine on the summer pole, less energy needed, but maybe manipulating the depth of the biological layer would be harder? For instance if you can regulate the spectrum from the mirrors, you can manipulate the character of the ice to a larger degree I susspect.

But it is all cold, even in the summer. Maybe that's not a major problem.

It is just a potential tool among many though. I will not be the one to say what happens.

Thanks for the chance to explain what I think.

SpaceNut · 2013-03-18 19:11:24

sure that is great for all the open teraforming ideas but what if its used to keep a domed habitat from a much larger energy production need by using them to offset the nightly temperature shift.

Void · 2013-03-18 22:36:48

I am very much in favor of many seedlings, and see what can take root best.

At some point a leadership will have to develop, and a first plan, second expansion, and so on. Perhaps there will be reliable and cost effective ways eventually to cover a significant portion of areas of Mars with domes that seldom leak for habitation by humans.

If I had my preferences, I would turn the north polar depression into one big shallow sea with domes over it. However that is at a scale where indeed it might be easier to add to the atmosphere and melt it that way.

For humble starts though, it could be true that something that would simply grow in ice with dirt sprinkled on it with a little added light, might release methane, which might assist as Terraformer would paraterraforming Mars up to 11 Mb. In the end though it must be about economics. How to get the most for the least effort in this case is valid I think. I cannot predict which methods will play out the best 20-50 years from now with changing technologies, and not understanding how the pattern of approach to Mars will unfold.

So, nuture all the ideas, and plant the ones that have a reasonable chance, and favor the ones that take hold like a bad weed.

Void · 2013-03-22 14:31:10

Another thought I have had is that if mirrors could melt a layer of dirt 6 feet down, then there might be the possibility of a water table.

In that case it might be possible to actually have that drain off of the sides of the ice cap into rivers and streams.

It is possible for a river or stream to run on Mars today, provided it is ice covered, and has a source of melt water.

Having done that, then it might be possible to have lakes (Ice covered, and maybe dome covered), for aquaculture.

I would be most interested in putting enclosures inside of those lakes at depths of 33 feet or more, where a simulated Methane seep could be created. Such could run year around to provide food for human inhabitants of Mars. (See also the life support section, for a thread where I have put references to Methane seeps).

Obviously if the atmospheric pressure could also be boosted to 11 mb or more (The more the better), this scheme would be even easier to implement.

***Here is the material I posted in the life support section which I think is related***

If animal food is also considered, I would go ahead and work with cold blooded water animals.

If salt water, then from the polar areas, though generally slow growing, requiring water quite cold.

But not restricted to cold water, if you add more heat and deal with greater pressures for the enclosure.

Cold blooded animals require less food for their biological budget, I think quite a lot less, and so also likely would consume less Oxygen.

Shellfish, and fish I suppose.

Another point being that it is possible to power something like that not only from sunlight, but from chemicals, simulating a cold Methane seep.

http://en.wikipedia.org/wiki/Cold_seep

This process of obtaining energy from chemicals is known as chemosynthesis.[3]

A mussel bed at the edge of the brine pool.During this initial stage, when methane is relatively abundant, dense mussel beds also form near the cold seep.[3] Mostly composed of species in the genus Bathymodiolus, these mussels do not directly consume food.[3] Instead, they are nourished by symbiotic bacteria that also produce energy from methane, similar to their relatives that form mats.[3] Chemosynthetic bivalves are prominent constituents of the fauna of cold seeps and are represented in that setting by five families: Solemyidae, Lucinidae, Vesicomyidae, Thyasiridae and Mytilidae.[5]
This microbial activity produces calcium carbonate (Ca C O3), which is deposited on the seafloor and forms a layer of rock

I don't know how edible those are, but it is worth investigation I would think.

The calcium carbonate might be an objective in it's self.

A mussel bed at the edge of the brine pool

The Microbes that feed the filter feeders could run variously from such sources. When the sunlight was more seasonalbly available, then tilt the exosystem to that, and otherwise tilt it to being chemical driven.

The tanks where the animals were kept could be relatively pressurized, and if desired less pressurized tanks could foster the microbial population.

This could be convieniently done by having a tank inside of a tank. More or less a enclosed pond with cold water where the algae, and microbes that feed on chemicals would be multiplied. At temperatures +/- 5 degrees. Therefore, a vapor pressure not much more than Martian ambient. Therefore the dome holding the pressure and vapor pressure could be substantially minimal.

As for the animal tank, put that down about 33 feet in the water, (That is about 330 mb pressure) saturate it's water with disolved gasses of O2 and N2, warm it to foster animal growth.

If other organisms that do not have bacterial in them that harvest energy from Methane:

There would be two mehods to get the microbes from the cold water to the animal tank. Either they would have to be filtered out in a fine filter, and back flushed into the warm tank, or if you had solar concentrating mirrors the water could be pumped from the bigger cold tank during the day, warmed, and then pumped into the animal tank.

As for harvesting the animals, I guess if it is shellfish, a robot could do that. If it is fish, perhaps a duct would allow them to circulate to a holding tank where humans could be present.

I would think this would occur at higher lattitudes where there is lots of ice, but maybe if an aquafer were available at lower lattitudes, then that way.

Last edited by Void (2013-03-22 14:38:04)

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#1 2012-09-03 10:43:48

orbital mirrors

#2 2012-09-09 04:54:44

Re: orbital mirrors

#3 2012-09-09 14:50:23

Re: orbital mirrors

#4 2012-09-09 18:57:55

Re: orbital mirrors

#5 2012-09-09 19:18:25

Re: orbital mirrors

#6 2012-09-10 04:45:50

Re: orbital mirrors

#7 2012-09-10 08:40:20

Re: orbital mirrors

#8 2012-09-10 19:55:58

Re: orbital mirrors

#9 2012-09-10 21:04:04

Re: orbital mirrors

#10 2012-09-11 14:04:03

Re: orbital mirrors

#11 2012-10-23 05:32:20

Re: orbital mirrors

#12 2012-10-23 13:40:06

Re: orbital mirrors

#13 2012-10-23 14:11:39

Re: orbital mirrors

#14 2012-10-24 09:07:24

Re: orbital mirrors

#15 2013-03-17 11:06:01

Re: orbital mirrors

#16 2013-03-17 11:22:30

Re: orbital mirrors

#17 2013-03-17 21:43:44

Re: orbital mirrors

#18 2013-03-18 19:11:24

Re: orbital mirrors

#19 2013-03-18 22:36:48

Re: orbital mirrors

#20 2013-03-22 14:31:10

Re: orbital mirrors

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