Steven Wintergerst's Terraforming Method
written by Steven Wintergerst on June 23, 2005 | contact me
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Terraforming does not require us to make another world 100% earthlike. We are also not under any requirement to ensure that every species that exists on earth will be transported to the new world. In fact, the cruel truth is that the only species that has to be able to survive on this other planet is humans. Certainly, this will require some manner of plant life to produce the oxygen we need, and certainly, colonists would be more pleased with the results if it contained much of the scope and beauty of the natural world, but technically, so long as humans can live on the surface unassisted by technology, the planet is terraformed.
Terraforming has never been done before, and therefore, it is an art, and not a science. Science is based on cold facts, calculations, and experience. Art is based on intuition, guesswork, and innovation. While successful terraforming must be based on science, until the process has been done several times, it will remain an art.
Mars, although a dismally unearthly place holds the most interest, as what may be our first potential terraforming project. However, before we begin terraforming, we must discern what it is about Mars that is unearthly. It will be impossible to make Mars more earthlike without knowing what the differences are. Once the differences are known, we can focus on those differences which are critical to human survival, and those that can be changed.
RADIATION: The thinner atmosphere and lack of a magnetosphere allows larger doses of radiation to reach the surface of Mars. Thankfully, since Mars is geologically dead, very few surface, or near surface radioactive materials exist. Robert Zubrin predicts that in any realistically terraformed Mars, the atmosphere will be thick enough to shield against cosmic radiation, and background solar radiation, but not solar flare activity.
SUNLIGHT: Less sunlight reaches the surface of Mars. Most plants seem to adapt well enough to lower levels of sunlight, and mirrors may be able to provide extra lighting for those that cannot.
Having determined the major factors that make Mars different from the Earth, it is time to determine why these differences exist.
WHY IS THE ATMOSPHERE WRONG:
The atmospheric composition of Mars is quite similar to that of Venus, and probably represents the fact that photosynthesizing life has never been able to establish a strong foothold on the planet.
The low atmospheric pressure is caused by a number of factors:
1: Excavation: The numerous large impact craters prove that Mars was heavily bombarded at some point. When asteroids, and comets hit a planet, they make a big splash. This can throw rocks clear across the planet, or into space, and it can do the same thing to the atmosphere above the rocks. Some people suggest that 90% of the original Martian atmosphere has been lost in this manner.
2: Erosion: Without a magnetic field, the charged particles of the solar wind slam directly into the Martian atmosphere. This pushes some of that atmosphere into space along with the solar wind.
3: Boil off: Escape velocity for a planet is directly related to the gravitation of that planet. Every particle of air has a certain speed. Temperature is an average measure of that speed, and on Mars, the ambient temperature of the air is high enough that the average hydrogen molecule is capable of attaining escape velocity. All that is needed is motion upward, and any loose hydrogen particles are lost. When mars was somewhat warmer, oxygen molecules might have likewise been capable of attaining escape velocity.
WHY IS THE GRAVITY SO LOW: The surface gravity for any body is determined by the overall mass of the body, and the diameter of that body. Mars has a surface gravity of 38% earth because it is composed of far less matter, and is only slightly smaller in diameter.
WHY IS THERE NO MAGNETOSPHERE: magnetospheres in earthlike worlds are believed to be caused by the dynamo effect. Spinning liquid metals in the core of these planets produce a Magnetic field. Either Mars has no liquid metallic core, or its core is no longer spinning. Since the surface of the planet is spinning, we can conclude that the core of Mars is no longer liquid.
WHY IS THE RADIATION SO HIGH: Mars receives more cosmic radiation because it has no magnetosphere to shield it, and less of an atmosphere than the earth. Likewise for the solar radiation. Mars has less terrestrial radiation because its surface material has been on the surface longer.
WHY IS THERE LESS SUNLIGHT: Mars receives less sunlight because it is farther away from the sun. Since the sun shines in all directions, the power of this sunlight follows an inverse square to the distance from the body.
WHY IS THE TEMPERATURE WRONG: Mars has a lower temperature because it is farther away from the sun. Its temperature is lower, and fluctuates more because there is less air, and water to trap radiation in overnight.
CHANGING ATMOSPHERIC COMPOSITION: Plants change the composition of the atmosphere all the time, they take in Carbon dioxide and water, and use solar power to produce oxygen and sugars. If plants can be made to survive on the surface of Mars, we will be going a long way towards our goal of a terraformed Mars.
Machines capable of performing this transformation also exist, but they do not reproduce on their own, they cost a lot of money, are bigger, and bulkier than seeds, and require maintenance that plants do not require. Thus, to convert CO2 into O2, plants are the best choice.
If Mars happens to have an overabundance of water, it would be possible to electrolyze this into hydrogen, and water. Much of the hydrogen should attain escape velocity, and leave the planet, so this is another way to increase atmospheric pressure. I wouldn’t necessarily recommend this process though…
Changing the atmospheric composition will eventually make air that is more breathable for animal life. However, oxygen is less dense, and not such a good greenhouse gas compared with CO2. Converting the atmosphere in this way is likely to lead to a decrease in atmospheric thickness, as the atmosphere is converted into solid biomass in the soil, and a decrease in temperature, as the greenhouse effect of CO2 is reduced.
A thinner atmosphere like this would be better for orbital photo-reconnaissance, as the satellites could get close to the ground, but it is not so good for ground based exploration, as there is less atmosphere to aerobrake, and parachute through. Colder, and thinner air would also not be good for life.
CHANGING ATMOSPHERIC THICKNESS: The atmospheric pressure must be increased significantly. We must be able to ensure that water (and therefore blood) does not boil away at ambient temperatures, and to do that, we need a thicker atmosphere. One sure way to increase the thickness of the atmosphere is to increase the temperature of the planet. This can be done by producing greenhouse gasses, using mirrors to reflect more sunlight onto Mars, or by decreasing the albedo over the illuminated polar ice caps.
It is generally agreed that melting the ice caps just a little should thicken the atmosphere, which, since CO2 is a greenhouse gas, should melt even more ice cap in a positive feedback loop. How far this loop can be pushed, and what the final temperature, and density of the atmosphere would be is uncertain. Some suggest that we can attain an atmosphere one third as dense as that of the earth in this manner. I do not think they have accounted for converting this into oxygen though.
It may prove necessary to add volatiles from elsewhere. The idea of redirecting comets to Mars has been suggested for this purpose. Redirecting comets is sure to be expensive, and getting comets into the atmosphere in such a way that they do not excavate out more air may prove difficult though.
Increasing the atmospheric thickness would produce an obstacle to orbital photo-reconnaissance, as the satellites would have to be farther away, but it would be good for ground missions, as there would be more atmosphere to aerobrake, and parachute through. A thicker atmosphere would also be good for terrestrial life, especially plants.
While increasing the atmospheric thickness is necessary, doing so alone may prove futile in the long run. This is because the solar wind causes erosion of the atmosphere, and certain air molecules would be subject to boil off. Finding ways to reduce, prevent, or counter these effects will be necessary.
CHANGING GRAVITY: Gravity is related to the mass, and diameter of a body. Thus, there are only two known ways to change gravity: Increasing the Mass of the planet, or decreasing the diameter of the body.
Increasing mass could theoretically be done my bombarding Mars with asteroids and such, but the fact is that moving them would be expensive, and achieving any significant change in mass would leave us with an unrecognizable world with totally different terraforming needs.
It may also be possible to use a very large particle accelerator to produce a quantum black hole. Dropping this tiny black hole into the center of Mars would cause the planet to shrink eventually. However, it is likely that the shrinking would be a cataclysmic, unstoppable process, leaving us with a larger quantum black hole where Mars once was. Most people feel that terraforming a black hole would be impossible.
One might imagine using powerful electromagnets to trap the black hole inside some sort of machine which would be able to allow only certain amounts of matter into the black hole. Such a machine is sure to be highly expensive, and finding a power source sufficient to keep it running indefinitely would prove to be a challenge…
In my opinion, changing the gravity will not be possible, or if possible, it will not be a worthwhile effort. Doing so is sure to cost enormous amounts of money, and leave us with a Mars that is totally unrecognizable. Whether this different Mars would be easier, or harder to terraform is unknown, but any efforts to terraform it would have to start from scratch.
The low gravity of Mars has a number of benefits. It will make lofting material into space much cheaper, so that Mars may become the food export capitol of the solar system. The only real drawback to a low gravity Mars is the possibility of boil off.
If we can find some way to prevent the loss of hydrogen, and possibly oxygen, or even if we can just find an easy way to replenish losses, the gravity problem becomes a non-issue. I’ll have to look into this later.
CHANGING THE MAGNETOSPHERE: Mars is rotating, so all that is needed to get a magnetosphere is to heat the core of the planet up until the core is molten liquid again. Of course, this is easier said than done.
It is likely that any processes that increase the gravity on Mars would also turn the core molten again. Alternately, we could produce an enormous parabolic mirror, and focus the sun’s rays on the planet to melt it. Huge nuclear weapons might also work, and some have suggested that he tidal forces caused by a Luna like moon being placed in orbit around Mars might work.
To be completely honest, all of these ideas sound overly expensive or dangerous. Also, any process that melts the core is also likely to melt the surface, boil off much of the atmosphere, and set the terraforming schedule back by several centuries while we wait for the surface to cool. Whether human effort can reasonably be expected to melt a planet other than earth in the near future is doubtful. Like the gravity issue, I believe that a simulated magnetosphere would be much safer, and easier to produce.
CHANGING RADIATION: One way to change radiation would be to produce some simulated magnetosphere. This would basically be a large electromagnet placed so that the magnetic field is located between the sun, and Mars. The coil needed to run the magnet could be located in the L1 point of the Sun-Mars system, in a n orbit around Mars, or on the surface of Mars itself.
Another way to provide radiation shielding would be to greatly increase the atmosphere. If the atmosphere were sufficiently thicker, the radiation would be blocked by the sheer bulk of it. Sadly, this would require an atmosphere much thicker than on earth, requiring the import of volatiles, as through cometary impact. We also cannot make the atmosphere too thick, for at a certain pressure, it will kill humans. It is likely that sufficient shielding can be produced without killing humans, but this may limit underwater options, such as ships, or diving, where the pressure would be even greater.
A third way would be to custom design gasses that block harmful radiation. The types available are probably limited, and unless genes to make some common organism on Mars produce the gas can be developed, it would add an additional strain on Martian manufacturing. It is unlikely that specialized gasses can provide comprehensive radiation protection.
CHANGING SUNLIGHT: While it may be theoretically possible to move the orbit of Mars closer to the sun, a more cost efficient means of increasing sunlight is probably through refraction, reflection, or absorption and re-radiation of the sunlight itself.
In space, gravity allows refractive lenses of any size to be built. However, micrometeorites are likely to noticeably pit away any such physical lens. Quantum theories however indicate that a large mass will bend sunlight as well, so placing a very large mass in between the sun and mars might work to actually focus more light on the planet. The L1 location between the sun and Mars would be an ideal place to locate such a quantum black hole.
To be effective, this mass would have to be extremely dense. Otherwise, it will simply block out more sunlight than it refracts. A quantum black hole might be of use in this process. Large particle accelerators are already being built to produce such objects today.
The speed at which a black hole evaporates depends on the mass of the object itself. To make a black hole that can last, we need something that can tip a scale a bit. Even then, we might need to feed it. Thankfully, the solar wind, and sunlight could be directed on it, each of which contains some mass, perhaps enough to keep the body from fizzling. Otherwise, shipments of materials from elsewhere (Such as slag from mining in the asteroid belt perhaps?) might be needed to “feed” our black hole.
Of course, the L1 point is not entirely stable. Material in this point will tend to move to one or the other masses in the system. Having a black hole reach Mars would likely spell the end of mars, and having one reach the sun would likely spell the end of virtually all life in the solar system. Thus, this idea is a high risk proposition, and one which I do not recommend for various other reasons as well.
Reflection requires us to place some shiny surface so that sunlight bounces off the sun, and onto Mars. Since sunlight diffuses, it will be necessary to place reflectors close to Mars. The L2 point, being behind both the sun, and Mars is one natural location, although this area may be shaded by Mars itself. Orbital Mirrors might also be of interest.
Typically, solar sail material is considered to be a prime candidate for reflecting sunlight onto Mars. Since these devices will be pushed away from the sun, certain station keeping procedures may be different from regular satellites. A space-made solar sail does not have any of the problems associated with deploying devices sent from Earth, although it supposes that a space based industry will exist.
Solar sails could be built from one of the Moons of Mars, and awkwardly maneuvered into an appropriate orbit from there. It is generally believed that significant changes of overall temperature cannot be easily achieved by using solar sails, although they may be used to melt the ice caps. Solar sail material could also be shaped, to provide convex mirrors, capable of operating at a fair distance from Mars.
A slightly different process would be to trap reflective metal particles in a large magnetic field. This would require very little space industry, and could provide a large reflective surface without much precision engineering. Sadly, such a “mirror” could not be shaped, or directed with any real accuracy.
In natural materials, sunlight is typically absorbed, and re-radiated as heat. This produces a very diffuse, and unproductive radiation. However, it is possible to use solar panels to absorb radiation, and then use the energy obtained to power lasers in order to reradiate that sunlight. Using lasers would provide a concentrated light source that could be position at a very large distance without much loss of power. In fact, the nature of lasers would make placing the devices very far from Mars quite reasonable. A satellite of this nature might be used to provide more “sunlight” to Mars from a distant point such as the L3, or L4 points of the Sun-Mars system.
CHANGING TEMPERATURE: Any process which provides a thicker atmosphere, or more sunlight to Mars will increase the Martian temperature. Additionally, the introduction of chemoautotrophic life, such as deep underground species of bacteria on earth, would add a very slight metabolic temperature increase to the planet.
A thicker atmosphere, and liquid water on the surface would both make the temperature swings less severe. Also, any scheme to provide more sunlight to Mars, which shines this sunlight onto the dark side of the planet will moderate temperatures.
Increasing the Gravity of mars would also increase the temperature of the planet, at least while the gravity was being increased. However, none of these schemes sounds very promising, and I would not recommend trying many of them.
A few ideas to raise the temperature in unorthodox ways have also been suggested. The most likely such idea is to cover the planet with radioactive debris from earth. This would indeed raise the temperature, however, I believe that the added radiation would be unsafe.
A slightly more sane suggestion might be to place radioactive material in deep caverns, lined with lead. The lead would stop most of the radiation from getting out, but would conduct the heat fairly well. The trouble with this idea is that moving radioactive material from Earth to Mars is sure to cause some arguments, and finding enough lead to line the caverns safely is also going to be hard to do. Locating appropriate caverns on Mars may or may not be an issue.
Frankly, I feel that a sufficient temperature change could be achieved by increasing the thickness of the atmosphere, adding greenhouse gasses, and using reflective devices to increase solar radiation should be sufficient.
With this knowledge of the Martian environment, a more or less reasonable plan for terraforming Mars can take shape. I feel that this plan should be divided into four major time periods.
We have already begun the initial steps necessary to terraform Mars by initiating a systematic exploration of the Red Planet. Russia had a number of early successes, and some very informative failures, which prompted the US to establish their own somewhat more successful missions.
From Mariner to Viking, to MOC and Sojourner, the United States has continued to provide extensive information on the whereabouts of water on Mars, as well as developing new landing techniques. Other government organizations, such as Japan, and the ESA are also beginning to try their hand at Mars exploration.
Private organizations such as the Mars Society now are hoping to provide more ground truth information on Mars, Mars Resources, and the effects of the Mars environment on humans. While their efforts seem to be bogging down, I have every hope that their goals will be achieved.
It is safe to say that research on Mars, whether intended for terraforming or not, will continue to produce more accurate data from which terraformers can work. Once humans are on Mars, the impetus for the first piece of real terraforming hardware will exist.
On the surface of Mars, humans are fairly well shielded from background radiation, but solar flares will still prove a problem. Solar flares produce solar storms, which is a dense stream of highly charged particles streaming out of the sun. When these particles reach Mars, there is a problem.
Since we are talking about a flow of matter from one mass to an orbiting mass, it would be possible to trap these charged particles with an appropriate piece of equipment located in (or very close to) the L1 point of the Sun-Mars system.
A nearly suitable piece of equipment has actually been developed, and is known as a Solar Wind sail. Solar wind sails are composed of a wide wire loop attached to a power source. When electricity is run through the loop, it becomes an electromagnet. This solar wind sail was designed to catch onto the charged particles of the solar wind, and ride it. However, if placed in the L1 point between the sun and Mars, such a device would actually be able to catch the charged particles heading to Mars.
I believe that the safest way to set up such a magnetic field would be with the poles perpendicular to the plane of the ecliptic. Since charged particles spiral out from the sun, a somewhat elongated shield would help to block them as they curve along towards a moving Mars. Setting the shield up in this orientation would also reduce the risk of radiation trapped in the shield reaching Mars in the event that the magnetic field was ever turned off.
Since the magnetic field acts as a solar wind sail, there will be an outward push on the craft. It may be possible to place more than one device like this close to the L1 point, so that there will be multiple backup devices in the event that one should fail, or need to be turned off for any reason.
On Mars, it will be desirable to establish some form of life. On Earth, we have discovered species of chemoautotrophs, most of which are very small single celled organisms. Most species use iron pyrite, and some form of hydrocarbon as food. On earth, it is typically believed that hydrocarbons are formed from decaying surface organisms, although an alternate suggestion claims that they are the result of early bombardment from carbonaceous meteorites.
On Mars, there has not been an extensive biomass, but there has been extensive bombardment from all kinds of meteorites. It is possible that there will be sufficient hydrocarbons from carbonaceous meteorites to allow some chemoautotrophs to survive. Thus, we might seed the planet with these organisms, although they really don’t do much that surface organisms would notice.
However, with a solar flare shield in place, it may be possible to grow somewhat more advanced plants, and plant like species on Mars. Snow algae, for example is a simple single celled organism, which has been proven capable of surviving in extreme cold, and atmosphere with virtually no oxygen. Whether the low atmospheric pressure, and dryness of Mars is suitable for the remains to be seen. Lichen has been proven capable of surviving in extreme dry, and cold environments. However, whether the oxygen poor, thin atmosphere is to their liking is unknown. I suspect that under a slight increase of atmospheric pressure, either of these species might survive fairly well on Mars.
At this time, exploration, and mapping of Mars is likely to continue, under the efforts of human explorers in sealed habitats. These explorers are sure to want some fresh food, and setting up greenhouses is a natural extension of this desire. It is possible that excess oxygen might be produced in these greenhouses, beyond what is needed for humans, and various equipment. Such an excess is no problem, since the Martian atmosphere is large, and it can easily be exchanged for more CO2. Doing so would be among our first pitiful attempts at increasing the percentage of available oxygen in the atmosphere.
Oxygen producing plants, on their own would actually incorporate atoms from water, and carbon dioxide into their cell structures, resulting in a net loss of atmospheric pressure on Mars. Also, since they would give off oxygen, which is not as good of a greenhouse gas as CO2, extensive plant use on Mars would actually make the planet colder. At this point, that is not an issue, and since the atmosphere must obtain a higher percentage of oxygen anyway, we might as well get started. Later on, we can produce super greenhouse gasses, if necessary, to reverse this process.
Major Terraforming Processes
By this point human activities on Mars should be providing us with a fairly accurate estimate of the volatile inventory on Mars. By volatiles, I am referring to Carbon, oxygen, hydrogen, and Nitrogen, the components necessary to create a breathable atmosphere, water, living organisms, and organic topsoil. A truly terraformed Mars will need some of all of these materials, and determining whether there are any planet-wide shortages for our purposes is essential.
Since the solar wind has been stripping the planet of it’s atmosphere, and since hydrogen is capable of reaching escape velocity at the current temperature, it uncertain whether or not sufficient Martian volatiles still remain on the planet for an effective terraforming to take place.
Many people believe that most of the hydrogen is frozen underground as permafrost water ices. Others argue that this is where the CO2 is trapped, as dry ice permafrost, and some suggest that the CO2, water, and Oxygen has actually been chemically bound to the rocks as rust, and other forms of oxidation, so there is a good hope that enough volatiles will remain for a proper terrforming to occur without the need to import volatiles from elsewhere.
There actually are large reserves of volatiles in fairly accessible forms in space. Hydrogen is the most plentiful material in the solar system, and makes up over 75% of the solar wind, which pushes tons, and tons of the material past Mars each year. Comets are composed of water, dry, and ammonia ices, representing a very earthlike proportion of volatiles. Since Comets change course randomly due to the influence of their tails, redirecting a comet should not be much of a serious problem if it proves necessary.
Getting these volatiles into Mars without causing a net loss in atmosphere is another question entirely. Solar wind typically strips off the atmosphere, but perhaps if we could shield against its usual path, we could also direct it in without producing significant losses of atmosphere.
Comets present a more serious problem. When asteroids hit Mars, they crater the surface, but comets “crater” the atmosphere, exploding inside the atmosphere, splashing out large quantities, some of which will never return. It may be necessary to slow comets significantly, or even break them up into tiny pieces before sending them down to Mars, in order to insure that the atmosphere is not splashed out. This will add significantly to the cost, but if the payoff is a second habitable world, I think the returns will eventually be worth the effort.
So long as we are crashing large objects into Mars, I suggest that we make the craters they cause serve a worthwhile purpose. Eventually, water should flood the lower elevations of Mars. This will produce a very large ocean in the northern hemisphere. This northern ocean will be free to circulate across the globe, making the northern hemisphere have a very uniform temperature. In the south, however, there will only be one or two seas, in the impact basins of Hellas, and perhaps Argyre. Since these seas are land-locked, there will be very little temperature mixing here, and temperature variations will be extreme. Also, since sea life will be unable to travel from the northern ocean to these southern seas, ecological disasters might be more common.
Cratering produces massive amounts of energy, similar to nuclear explosions. Explosions have been used in mining, and other work where excavations are necessary, and therefore, if we are going to bombard the planet, it might be worthwhile to aim some of those chunks in order to crater-excavate a canal from the northern ocean to the southern seas. This is probably not necessary, but if we happen to be bombarding Mars anyway, we may as well get some useful digging done from the process.
As I have mentioned, it may be that mars has enough volatiles already, and moving comets, or redirecting the solar wind is not an issue. In this case, the terraforming process can go straight to warming the planet, and melting the ice caps to get the volatiles we need.
Several methods for warming the planet have been suggested. Most of them hinge upon the concept of positive feedback. It is believed that by melting the polar ice caps of Mars, we will be releasing significant quantities of Carbon Dioxide, and water vapor into the atmosphere. Both of these are greenhouse gasses, and both block different wavelengths, so that they work far better together than apart.
It is believed that by melting a little of the ice caps, we will produce a noticeable greenhouse effect on Mars, which will cause more of the ice caps to melt, which will produce more of a greenhouse effect until all of the ice caps are melted, and a significant quantity of the water and dry ice permafrost around the planet have also been melted. Some extrapolations suggest that this will provide us with an atmospheric pressure of about 1/3 the pressure of earth’s sea level.
This would be more than enough if the atmosphere produced was breathable. Sadly, a pure CO2 atmosphere would not be breathable, and the processes whereby CO2 are converted into Oxygen generally leave a large amount of solid matter behind. Thus, I have suggested that volatiles from other sources, such as comets may be necessary. Further research is likely to provide us with a more exact answer to this question before any actual terraforming takes place.
With positive feedback, the question of heating the whole planet is simplified somewhat to just heating the polar areas. This is a much less daunting question, and a number of suggestions have been brought up.
One possibility is to lower the albedo of the polar ice caps. Albedo is a measure of reflectivity. Ice is highly reflective, which keeps it from heating rapidly. Covering the ice caps with a dark dust might cause them to melt sooner, and more completely. Some have suggested blanketing the ice caps by detonating nuclear warheads in a nearby deposit of dark dust. The nuclear weapon would certainly melt some of the ice cap, and the black dust should spread over much of the rest.
Of course, melting an ice cap will move the dust deposits above it, so the effectiveness of this idea is not totally proven. Another problem is that anything which has a low albedo can also decrease in temperature rapidly once it is not being heated. Therefore, it would be best for the ice cap to not have dark dust on it once winter for that hemisphere rolls around.
This plan has some benefits. The shifting ice melts would likely remove the dust before winter started again, so the albedo problem is not a drawback during winter. The real questions with this method are whether the dusting process would be provide significant results, and whether popular opinion would allow nuclear weapons to get shipped off into space. Space explorations, and nuclear payloads generally spark intense demonstrations, so some other method to distribute the dust onto the caps would be preferable.
An alternate suggestion is to use space based mirrors to melt the ice caps. This would likely prove expensive. The mirrors might have to be built in orbit, and could require extensive space based industry around Mars. Whether developing such an industry would be worthwhile is unknown.
A third possibility would be to use super greenhouse gasses. Kim Stanley Robinson’s Mars trilogy rests on the assumption that this would work. About a hundred factories the size of a Volkswagen have been suggested as effective, and perflourocarbons have been recommended as the appropriate gas.
This is probably a workable idea, and may prove cheaper than solar mirrors. Maintenance on the planet is likely to be much safer, and cheaper than maintenance to orbiting stations.
I would suggest that it should be possible to insert genetic material into plants so that they produce these perflourocarbons. Since these gasses are safe for humans, even food plants could be used to produce the gas. It could be used as a buffer in habitats, and vented to the surface when excesses occurred.
Using genetically altered plants to produce greenhouse gasses could be a slower, and less precise method than using factories, but since one genetically altered seed could easily be converted into fields of the stuff, it would drastically cut down on the needed shipment sizes sent to Mars for the terraforming process, and since many plants require very little maintenance, the work hour cost would also go down.
Crops producing perfluorocarbons would help to terraform Mars while they helped to feed Mars. Soon, it would be possible to introduce less demanding species onto the surface of Mars itself, allowing more rapid transformations of the surface.
There is a slight risk that these crops could grow out of control, producing too much perfluorocarbons, but this is unlikely. In the early days, an over productive greenhouse could simply be opened up, to kill off the plants, or humans could weed them out with some efficiency. Once the temperature got too hot, the crops would be injured , and wilt. Plants without the perfluorocarbon genes would be slightly more efficient, so these could be introduced to out-compete any excessively effective greenhouse plants, and solar wind shielding could be turned off to destroy hemispheres of over productive plants if the need arose.
All these choices are possibilities that have jumped into my head in ten minutes of thought. Certainly, there are numerous other ways to prevent excess greenhouse gasses from being produced by plants.
In this final phase, we will do the finishing touches on Mars. Virtually all plants will be grown under the Martian sky, with domes necessary only for human and animal life. Soon, even they will be able to move out into the wide expanses of a terraformed Mars. By this time, Mars will have been invested in heavily, and there will be a large industrial infrastructure on Mars, capable of producing most anything needed for this phase of terraforming.
Here, a few finishing touches will need to be taken care of. Temperature, and sunlight requirements will be tweaked to satisfy, radiation shields will be installed, and backup systems for them will be developed. Safeguards against loosing volatile gasses will be set up.
Some plants may require more sunlight than is available on Mars, and some animals may require “moonlight” signals for certain behaviors. Most economically important species are likely to be fine as is, but if not, orbital mirrors of various kinds might need to be developed. These would slightly raise the temperature of the planet itself, making less greenhouse gas necessary.
The cheap, and easy production of greenhouse gasses by plants will slowly be replaced by regular plants, and regular greenhouse gas factories, built on Mars at a fraction of the cost. Using factories will allow for more precise alterations of climate. Whether such a replacement should, or can be total is uncertain. I suspect that a few greenhouse producing plants will survive well into the next millennia, and there is nothing wrong with that.
The L1 solar wind shield will be backed up by surface systems, and perhaps a series of orbital devices, to protect the more productive areas in the event of a catastrophic failure. Ground based magnetic fields would be extremely easy to maintain, and might completely replace the L1 devices in later years, although if there are migratory species on Mars, this could prove impossible. Further research would be necessary on this point.
A last problem will be replacement of hydrogen. It is believed that water vapor will be subject to photo dissociation. That is, sunlight will break water vapor into hydrogen, and oxygen molecules. Hydrogen is capable of traveling faster than escape velocity, and the higher temperatures of a terraformed Mars could allow that to also travel faster than escape velocity, so this process could produce a net loss of water on Mars.
Whether this net loss is a large amount of water or not remains to be seen. If it is small, we might be able to have a terraformed Mars till the sun went red giant without needing to worry about it. If not, we might have less than a century of terraformed Mars before the planet becomes a desert. In this case, some safeguard would be highly desirable.
Since water is necessary for all living things, some way to prevent this loss may be necessary. Thankfully, the water vapor molecule itself is far too dense to ever reach escape velocity. Thus, one line of investigation might lead to gasses that block the wavelength of sunlight responsible for photo dissociation. Sadly, wavelengths close to this one are responsible for photosynthesis in plants. Blocking this wavelength might interfere with plant growth.
Since I have admitted that increasing gravity on Mars is not an option, the next most logical step would be to decrease temperature, which would lower the average speed of particles. Of course, this would not go well with terraforming, as we would have to drop the temperature below current average surface temperatures of Mars. All life on Mars would then need antifreeze for blood, making it impossible for humans to live there without their humanity coming into question.
If we could add a buffer gas to the atmosphere of Mars that was lighter than the gas we are trying to keep in place, it might be possible to weigh that gas down. Helium would be lighter than oxygen nitrogen, and even carbon dioxide. Small quantities of it are available in the solar wind. Some other gasses are also probably heavier than oxygen, and an easy supply, or at least a supply somewhere ought to be available. However, hydrogen is the lightest atom in existence, and nothing we know of would weigh it down.
It seems that it is impossible to trap hydrogen molecules on the surface of Mars. However, it might be possible to replace those molecules lost. The solar wind is composed mainly of hydrogen, and if we could only redirect this solar wind onto Mars, we would have a way to replenish our supplies of hydrogen.
Large electromagnets, such as those used in particle accelerators might be used to redirect the solar wind onto Mars. Sadly, such a process is likely to very expensive for only small returns. Solar power, of course is available for free in this area, but construction parts are still not free.
Another option would be modeled after the rings of Saturn. A wide array of dust particles such as those that make up Saturn’s rings should dissipate quickly. The force of the solar wind, random bumps into each other, and gravitational influences among them should have dispersed them entirely within a mere thousand years or so. Instead, they have remained virtually the same since the first telescope recognized them. Some force must be keeping the rings in place.
The force that keeps the rings in place has been discovered. Small moonlets in the gaps of the rings pull on the ring materials. Moonlets outside the rings pull outwards, and backwards, slowing the dust particles down. Once the moon has moved on, these particles are slower than their orbit dictates, and they fall inward.
If we could place sizable objects in an orbit just outside the orbit of Mars, these objects would pull on the hydrogen particles in the solar wind, slowing them, and forcing them to fall into the orbit of Mars, where Mars would hopefully sweep up some of them. This option assumes that Mars would not just push them away from it, and that the force of the solar wind pushing outward would cause large amounts of hydrogen to pile up in this area.
There are several sources for material that could be placed in orbit just outside that of Mars. Several US mariner probes were sent around Mars before falling into an orbit just beyond Mars. Several early Russian probes also were sent into this orbit. Perhaps some of these space craft could be redirected to get a small start on this project.
Small space probes are not likely to be significant in this effort, and I suspect that it will require a larger number of more massive bodies to achieve any noticeable effect. Thankfully, just outside the orbit of Mars is the asteroid belt. Redirecting asteroids is not as easy as redirecting comets, but I believe it can be done.
Carbonaceous asteroids, for example, are composed of hydrocarbons, a collection of chemicals somewhat similar to coal. Hydrocarbons contain large amounts of carbon, oxygen, and hydrogen. Current rocket fuels are usually composed of hydrogen and oxygen, or methane and oxygen. Both of these rocket fuels could be produced from the raw materials available on carbonaceous bodies, so there is a source for fuel in the asteroid belt.
Where there is fuel, there is motive force, so we should be technically able to move at least some of the asteroids. Since we are using these asteroids as nothing but mass, their composition once they arrive in their new orbit is unimportant. However, it would probably be a very good idea to leave some fuel on them for station keeping purposes.
With Mars shielded against radiation, heated, with a thicker atmosphere, and systems for reducing hydrogen loss, or replenishing it, the terraforming process requires only one more thing.
It will probably take some time to change the atmosphere from mostly carbon dioxide to mostly oxygen. Plants could do it, but there are also mechanical processes that could speed things up. Once that is done, humans can walk about on Mars without space suits, and terrafoming will then be complete.
1) Foundations of Astronomy, Fourth Edition By Michael A. Seeds. ISBN 0-534-26036-5
2) The Case For Mars By Robert Zubrin. ISBN 0-684-83550-9
3) Mining the Sky By John S. Lewis. ISBN 0-201-382819-4
4) Mars, The Living Planet By Barry E. Digregorio, Dr. Gilbert V. Levin, and Dr. Patricia Ann Straat. ISBN 1-883319-58-7
5) The Deep Hot Biosphere By Thomas Gold. ISBN 0-387-95253-5
6) N Space By Larry Niven. ISBN 0-812-51001
7) Red Colony Articles: Lichen by Kian Cochrane, Martian Boiler Room By Kevin Reimund, Perfluorocarbons By Alex Moore