April 06, 2005
Will Environmentalists Some Day Oppose Global Warming Of Mars?
Some day decades from now environmental extremists groups might try to sabotage a rocket launch carrying equipment to Mars for a massive climate engineering project. Artificially created octafluoropropane could trigger a melting of the Mars polar ice caps and make Mars much more capable of supporting life.
WASHINGTON—Injecting synthetic "super" greenhouse gases into the Martian atmosphere could raise the planet's temperature enough to melt its polar ice caps and create conditions suitable for sustaining biological life. In fact, a team of researchers suggests that introducing global warming on the Red Planet may be the best approach for warming the planet's frozen landscape and turning it into a habitable world in the future.
Margarita Marinova, then at the NASA Ames Research Center, and colleagues propose that the same types of atmospheric interactions that have led to recent surface temperature warming trends on Earth could be harnessed on Mars to create another biologically hospitable environment in the solar system. In the February issue of Journal of Geophysical Research-Planets, published by the American Geophysical Union, the researchers report on the thermal energy absorption and the potential surface temperature effects from introducing man-made greenhouse gases strong enough to melt the carbon dioxide and ice on Mars.
"Bringing life to Mars and studying its growth would contribute to our understanding of evolution, and the ability of life to adapt and proliferate on other worlds," Marinova said. "Since warming Mars effectively reverts it to its past, more habitable state, this would give any possibly dormant life on Mars the chance to be revived and develop further."
The authors note that artificially created gases—which would be nearly 10,000 times more effective than carbon dioxide—could be manufactured to have minimal detrimental effects on living organisms and the ozone layer while retaining an exceptionally long lifespan in the environment. They then created a computer model of the Martian atmosphere and analyzed four such gases, individually and in combination, that are considered the best candidates for the job.
Carbon and flourine would need to be concentrated from the Mars surface materials.
Their study focused on fluorine-based gases, composed of elements readily available on the Martian surface, that are known to be effective at absorbing thermal infrared energy. They found that a compound known as octafluoropropane, whose chemical formula is C3F8, produced the greatest warming, while its combination with several similar gases enhanced the warming even further.
My guess is that this would still be very difficult to do because a nuclear reactor would probably be needed to provide the energy for a chemical plant to fix the flourine to carbon. Also, a permanent human Mars colony or robots would be needed to carry out the needed work. The construction of a human colony would require much more material to be shipped to create livable conditions for humans far enough under the surface to provide protection from radiation.
The researchers anticipate that adding approximately 300 parts per million of the gas mixture in the current Martian atmosphere, which is the equivalent of nearly two parts per million in an Earth-like atmosphere, would spark a runaway greenhouse effect, creating an instability in the polar ice sheets that would slowly evaporate the frozen carbon dioxide on the planet's surface. They add that the release of increasing amounts of carbon dioxide would lead to further melting and global temperature increases that could then enhance atmospheric pressure and eventually restore a thicker atmosphere to the planet.
Such a process could take centuries or even millennia to complete but, because the raw materials for the fluorine gases already exist on Mars, it is possible that astronauts could create them on a manned mission to the planet. It would otherwise be impossible to deliver gigaton-sized quantities of the gas to Mars. The authors conclude that introducing powerful greenhouse gases is the most feasible technique for raising the temperature and increasing the atmospheric pressure on Mars, particularly when compared to other alternatives like sprinkling sunlight-absorbing dust on the poles or placing large mirrors in the planet's orbit.
How many gigatons would be needed? How much energy would it take to manufacture those gasses? How much energy would be required simply to gather and refine the raw materials?
Advances in robotics will eventually make climate engineering of Mars much easier to carry out. Fusion reactors (still a distant prospect) would probably weigh less than fission reactors and therefore would be easier to transport to Mars. This whole job will become much easier to carry out as a variety of new technologes are developed in the future for Earth-bound purposes.
I do not see Mars colonization as a cost-effective way to ensure the survival of the human race in the short to medium term. Mars is too costly to reach and too hostile to human life forms and to the life forms that humans use for food, medicine, and other purposes. At best only a handful of people could be transported to Mars to form a colony there.
If the goal is to ensure the human race's survival then the money spent on creating a Mars colony would be better spent on a number of other purposes. A great asteroid defense system could be built for a small fraction of the cost of setting up a Mars colony. Such a system would eliminate the biggest natural threat to continuation of the human species.
A massive volcanic eruption is another potential danger that could lead to billions of human deaths. Well, most humans wouldn't die from the initial eruption blast. The problem is that the sun would be blotted out (thereby rendering solar photovoltaic power useless). What we need is an uninterruptible power source. Today the only such power source we have is fission energy but cost and safety concerns have limited its use. Therefore if ensuring the continuation of the human race is the goal money allocated to accelerate fission and fusion energy research would be better spent than money allocated to a Mars mission.
Then we come to the human-generated threats to our continued existence. Most and perhaps all of those threats would probably pose a threat to a Mars colony as well.
First off, some humans may either intentionally or accidentally develop aggressive artificially intelligent robots. Well, Mars is not a place to go to escape from them. If robots some day become smart enough take over the Earth they will be able to build rockets and travel to Mars where they will be able to easily overrun any human Mars colony.
The nanotech goo idea is a human doom scenario where nanotech replicators start dividing uncontrollably and overrun the earth. The nanotech goo probably eventually lead to the overrun of a human Mars colony as well. The nanotech replicators would probably develop artificial intelligence because some of them would be programmed to construct complex systems. If the nanotech replicators become self-aware and highly organized they too would eventually mount a mission to Mars and wipe out humans on Mars.
About the only scenario where I see that a Mars colony might prevent the extinction of the entire human race is the case where a bioengineered plague would be unleashed in the human population. But my guess is we'd be better off spending money on biodefenses than on a Mars colony. Certainly that is true for the vast bulk of humanity that would still be here on Earth after a Mars colony is established.
There is a more fundamental reason why I oppose human species continuation as a justification for the creation of a Mars colony: I don't want to die either here on Earth or on Mars. Nor do I want to have the vast bulk of the people I know die while I (improbably) survive a while longer in a puny Mars colony. We ought to set our sights higher and aim at ensuring the continued life of the vast bulk of the human race, not just some small remote outpost living a tenuous existence in an extremely hostile environment. Efforts to set up a Mars colony seem to me misdirected as long as we do not have an asteroid defense system, fusion enengy, and last but not least, technologies for rejuvenation.
This debate was argued long ago (1970's) and the result was "The High Frontier", by Gerard O'neill. The L5 scenario is based on boring 1970's space and materials science technology. Developments in biotech and nanotech by 2030 will make the L5 scenario much more doable. Mars is a red herring.
While I also believe technologies for rejuvenation should be priority, I think we should not underestimate the importance of spreading ourselves throughout the solar system (and perhaps one day the galaxy).
As you stated, one expertly weaponized virus could potentially lead to the extinction of Humans on Earth.
A combination of the two tedchnological strategies should therefore be developed in concert if possible imho.
But why on Earth (actually why on Mars) did most of the atmosphere of the Red Planet vanish? It is known that once upon a time, the atmosphere of Mars was fairly thick...
It seems that because the mass of Mars was below a critical amount, the gravity of the Red Planet was probably not strong enough to compress the atmosphere, and hence the high altitudes of the upper atmosphere caused much of the gases to escape to the outer space after millions of years. Apparently, our planet does not have this problem because the mass of the Earth is greater, which makes it possible to compress the atmosphere close to the surface so that the gases do not escape from the Earth.
So when the human astronauts inject super greenhouse gases into the atmosphere of Mars, the very thin nature of that atmosphere will be an issue. We must make a reliable calculation for the feasibility of the Mars polar ice cap melting project. Otherwise, I am very much in favor of moving to Mars when I grow up.
For the cost of establishing a permanent Mars base we could instead build probably dozens (or hundreds?) L5 or Moon bases. But since I think the odds of any of us getting into an L5 colony or Moon colony are extremely low I am not excited by those prospects.
For the cost of a Mars colony we could instead build on Earth a great many sustainable dome cities or buried cities that could isolate themselves entire from a genetically engineered virus. Far more people could live in those dome cities than could live on L5 colonies built with the same amount of money.
Again, when it comes back to the desire to avoid death I keep coming to the conclusion that there are better ways to spend the money than in space. No matter what you propose to do in space I can propose to do something down here on Earth that will save more lives for the same amount of money.
fission reactors are being designed now for space ships to do extended trips with power intensive propulsion systems. obviously they are fission reactors at the present time since fusion reactors have yet to be demonstrated in the lab, much less in practical application.
what about a dome colony on the moon? it's closer and would be a lot more fun vacation to live at 1/6 earth's gravity and look out on the earth. i doubt it would be much pricier than the international space station.
"But why on Earth (actually why on Mars) did most of the atmosphere of the Red Planet vanish? It is known that once upon a time, the atmosphere of Mars was fairly thick..."
The current state of Mars Atmosphere is the way it is because of the temperature there.
Mars is cold, too cold. Once, when the heat of the Sun affected Mars more greatly, back when it was bigger or hotter, all of the elements that all the planets once had were much like those on Earth. Liquid water flowed when the temperature was right for that, and there was an atmosphere of those elements which we have today on Earth. But as the sun's rays ceased to shine so hotly upon Mars, those light elements became frozen. Now, there is no liquid on mars, and no ozone layer. Some portions of the light elements may have cooked off. But likely, a great deal of them have stayed frozen within the tundra crust of the red planet.
To effectively terraform Mars, more than chemical manipulation in the form of plant respiration or greenhouse gas injection will have to come about. What is needed to make mars habitable for human life is heat. So how do we heat an entire planet?
FuturePundit mentioned mirrors, but that is just on of many solutions. Clearly the easiest way is to increase the solar flux onto the red planet.
Large diameter Optical magnifiers mounted on satellites?
Solar collectors beaming energy?
Photo-voltaic powered space heaters?
Massive scale simultaneous exothermic reactions using air-spraying and surface soils?
Fusion space heaters?
None of these are feasible. Sustained long-term heat must be maintained, and it must be maintained throughout the entire sunside. The rotational rate of mars may be of some use in that regard, but the problem still stands that Mars is in great need of a fair amount of heat if life is to survive. Plants may be genetically modified to grow in the nitrogen rich fertile soils there, yet humans will never be comfortable until the atmosphere is within the comfort region of the human condition.
Large diameter optical magnifiers focusing the luminosity of the sun from far Mars orbit, effectively increasing the diameter of the sun as seen from Mars and focusing those rays upon mars light side could do the trick. The focused rays would have to be distributed over the whole planet's light side, and the satellite array would have to be large enough to collect enough flux from the sun to provide for liquid water on Mars. It would have to be a very great number of distributed satellites using very light very cheap and very precise magnifying lenses. The fun part here is that there would be warm spots until the entire array was up. This entire array could be manufactured on Mars from synthetic hydrocarbon based plastics. Of certainty is the fact that the planet's rotation would need to be considered. The entire scheme is dependent upon the manufacture of solar sail technology and the ability to spread large solar magnifying films out over a large enough area to collect enough flux.
The Key of this scheme is to augment the natural flux, not interrupt it. By adding more actual flux, the desired result may be achieved. The effective problem here is, however, just how much material needs to be placed out there, and how big do the satellite anchors have to be to counteract the force of the solar wind. It seems the ideal is a satellite of a mass and placement such that the gravity of the sun pulls just as much as the solar wind pushes. This free-of-orbit location would be close enough to the sun to capture more of its rays with a smaller surface as well.
But then of course one needs to determine whether an artificial gas casing layer such as the ozone layer would be necessary to account for the decreased gravity of the Red Planet.
Why does Mars have such a thin atmosphere?
Why is there a ring of asteroids outside the orbit of Mars rather than a planet?
The answers to these questions may be related - if the odds of intelligent creatures developing on a habitable planet is high...
At any rate, an extraterrestrial colony may be vital for the future of humanity after all. It's a huge waste of resources - unless you consider that most of the alternate uses of those resources are severely hindered or outright prevented by political controls. Get a colony out in the boonies and let them practice hard-core laissez-faire capitalism, and they'll happily crank out technological advances as fast as their numbers allow - and if they crank out babies as well, they'll fix any shortcomings in that area.
The human race used this technique once already, setting up a colony across the Atlantic rather than in deep space but with much more primitive technology, and it paid off handsomely in the long run.
How do you know that lenses would be cheaper than mirrors? My guess is the mirrors could be very thin.
I see both lenses and mirrors as problematic due to small asteroid hits. The area they'd need to cover would be very large.
I'd like to see some physics on the amount of additional energy we'd need to either produce in fusion reactors or funnel toward Mars with mirrors or lenses to warm it up high enough to make it livable for humans.
But if the intent is to create a non-Earth habitat where lots of people can live then aren't L5 and moon colonies more cost effective?
I think the odds of getting hundreds of billions or trillions allocated to constructing a Mars colony are lower than the odds of getting smaller amounts of money allocated to the development of fusion energy or an asteroid defense system.
Also, I do not see why I down here on Earth should want to spend a large amount of money to allow a small group of people who do not include me to go live on Mars.
I also do not expect a small Mars colony to innovate at even one millionth of the rate of the US population let alone the US, Europe, Japan, and China combined. There won't be enough brains on Mars to make a difference.
I have always been a big sci-fi fan but I don't see humans reaching out to colonize space until our energy situation has evolved to the next level. Probably fusion - plentiful, safe, non-polluting (in theory). To me this is a much higher priority considering that fossil fuels are going to become scarce around early to mid-century. If we do not use fossil fuels as a springboard to elevate energy technology to the next level, if we regress into a state of energy scarcity that persists and stifles research and progress, we may never get the chance again.
I am not an expert on planetary science, but it would seem that even if we made the martian atmosphere dense and warm enough to support human life, how will we fix the fact that Mars has almost no magnetic field and thus no protection from the solar wind? I guess solar activity could be closely monitored and people could retreat to their protective domes or whatever in the event of a storm. I wonder what a human born and raised in 30% of earth-normal gravity would look like.
"I wonder what a human born and raised in 30% of earth-normal gravity would look like."
You would like a nine foot freak who couldn't cut it in Earth's gravity well. When I was making the arguments for Mars exploration back in the late 90s or so I always thought that was a valid argument against, and in favor of orbital habits where you could create artificial spinning G...
I also think that Randall is overlooking capitalism and political concerns as to why people might want to hit the road, not to mention that solar sats would pay for themselves. And I'm not even looking at valuable properties you might find in terms of Helium 3 or in the asteroid belt...Because it's there, and it's probably very valuable is why there will be space exploration, unless Richard Branson and Burt Rutan are just silly and unreasonable people...
Of course, I use to think these settlements would be decent Star Treky places to live. I"m now convinced that they would look a lot like Deadwood or Outland...
Anybody read _the Greening of Mars_ by James Lovelock and _Red Mars_, _Green Mars_, and _Blue Mars_ by Kim Stanley Robinson?
I agree that energy research is more important than space exploration. With cheap energy we can do
What do solar satellites have to do with a trip to Mars? I think solar satellite construction would be a far more productive way to use a few hundred billion dollars than a trip to Mars.
But the people who want to hit the road to go to Mars today ask the rest of us to use the government's power of taxation to pay for their Mars colony.
Mars is not that valuable. It has an incredibly hostile environment for humans. It is incredibly expensive to get to and to maintain human life on safely. Technological advances that will make fusion reactors feasible would be much more valuable.
Branson and Rutan have no idea how to make a trip to Mars affordable.
Money spent to go to Mars would be better spent on medical research, energy research, and defenses against natural disasters.
Just curious. How old are you? Since you believe that we will conquer aging in your lifetime I would like to know what timeframe you were looking at. I'm 42 but my youngest is 3. So will I be the last generation to age-out?
Does one really have to be an extreame environmentalist to oppose this? I don't consider myself one, but I'm hesitent to get behind making any radicial changes simply because we don't know if there's primitive life there. Proof of nonterrestrial life would be huge. Worth risking the human species over, perhaps not. But primates have been around quite some time, I'm willing to side on the idea that we'll be OK for the next couple hundred years.
If space does not appeal, then how about research in life support systems. Life support systems allow humans to survive in any extreme environment, in space or on Earth: underground, undersea, nuclear war, biological war, etc.
Points in no particular order:
- A colony on Mars has defenses that no domed city on Earth could hope to use against a
plague: distance and sterilizing environs. If the goal is to "win" by having an outpost survive a doomsday plague, Mars is a far better choice than any place on Earth.
- Adding light to Mars is relatively easy; you could balance a solar sail between its own thrust and the gravity of Mars and shine light on the (night side of) the planet.
- Even Earth's magnetic field is not particularly protective against cosmic rays; that job is done with a ton of mass shielding per square foot. Magnetic fields are effective against low and medium energy charged particles, like solar protons.
- IIRC, some people have proposed "artificial magnetospheres" to provide both shielding from low-energy particles and drag against the solar wind.
I do not know when rejuvenation technologies will start extending life expectancy faster than we age. 2025? 2035? I figure 2050 at the latest.
- A Mars colony would need to be built underground due to radiation. We could build a similar sized and totally sealed colony under the Earth for a small fraction of the cost.
- If domed above-ground cities are all sealed off as soon as a plague is first discovered then some cities will remain uninfected. Most plagues are spread human-to-human.
- If the goal is to put a portion of the human race beyond the reach of plagues that could spread a few weeks worldwide before being detected we ought to have domed cities that each spend 2 months of the year sealed off. Different cities could be sealed off at different times with some overlaps.
- If the goal is to be able to have people who can fight a massive plague then what we ought to do is build a number of scientific mini-cities that are high isolation environments. Then we'd have lots of microbiologists and immunologists who could be protected from plagues and work on cures.
- Faster means of transportation between Earth and Mars using Earth orbit and Mars orbit nuclear or solar power stations sending concentrated laser beams at space ships might be the way to achieve faster transit times. Some of the laser power hitting a solar sail on the space ship could be converted to electricity to power the magnetic field.
- Moon bases and L5 colonies could each rotate thru periods of quarantine so that some would survive if a plague hit Earth and was going to wipe out the human race.
- I'd rather spend the Mars mission money advancing biodefense technologies. How about nanotech immune response devices floating around in our bloodstreams?
The more I think about it the more I think a Mars mission and a Mars base are premature by a few decades at least. There are more important areas of science and technology we should be pushing first.
Getting back to the actual article, it seems it would be much, much easier to set up a factory to pump out the super-greenhouse gas down here on Earth. Not much call for it though, unless a small, cold, nuclear armed state (Initials PRK?) wanted to hold the world to ransom...
Back to Mars now, and I disagree that it would be easier to make the factory than it would be to send gigatonnes of gas to Mars. If we sent it from Earth, yes, but what if we just diverted the course of a few water and CO2 ice comets? Note that 95% of the cost of this project is needed anyway for asteroid defence.
The idea of some suicidal/homicidal nut group making lots of flouropropane and then releasing it all at once into the Earth's atmosphere also crossed my mind as well. I wonder how much energy, raw materials, and money it would take to do it. Perhaps they couldn't hope to cause much harm before being detected.
As for diverting comets: Yes, that thought occurred to me as well. But I have no idea much water and CO2 are available to divert. My impression is that it is not much. People talk of really big asteroids being a kilometer in diameter. Well, that is not much.
I figure we'd have a better chance of developing some way to scoop up materials from a moon of Jupiter or Saturn.
Also, how much oxygen is in the soil of Mars? If we could bring enough hydrogen from elsewhere in the solar system could we make enough water to flood the place? Or would the thin atmosphere cause all the water to evaporate? We need a lot of oxyen and hydrogen to remake Mars. Anyone up on the proposals for how to do this? Surely this has been a topic covered by the Mars colony enthusiasts.
If you are genuinely afraid of a plague wiping out the human species on Earth, an underground city isn't going to do the trick unless it has a population of fanatics content to semi-permanently isolate themselves from all direct physical contact with the outside world. An ideal plague to wipe us out would be one that had a lengthy period of communicability without symptoms to achieve a very high penetration before anyone realized there was a problem. Our underground city need only admit one unknowing plague bearer to ruin everything. This is a bit more unlikely over interplanetary distances unless space travel becomes so cheap that the cost of establishing colocies on Mars and elsewhere becomes a minor concern.
I wouldn't expect to hear much discussion of going to Mars from Burt Rutan. He's a very practical guy focused on advancing through things that are already within our grasp if we only make the effort. I would surely rather pump a a billion dollars into his R&D with closer term goals that would still ultimately contribute to any eventual human exploration of Mars. We still aren't very good at getting humans to orbit and only a small dwindling group of elderly men have ever been beyond Earth orbit. We have plenty of work to do in the immediate neighborhood to better enable our reach beyond.
there's this goofy show that used to come on called "Sifl and Olly," where thse sock puppets goof off and do "interviews." Well, once they interviewed the planet mars. He told them that once his surface was thriving - cities, billions of people, animals. They asked him what happened, and he replies "oh, you'll see. you guys keep it up. you'll see."
oh, also, I see no reason to protest the changes on mars unless there's life there already. if we exterminate all life on the planet (assuming there is any), intelligent or otherwise, it's xenocide and obviously not justifiable. If there's no life, it's just a big dead rock and we're actually adding life to it.
Eric Pobirs has neatly refuted the "sealed city" defense concept. Look at what happened after 9/11: a few days without air travel and things were pretty screwed up. Two months a year of complete isolation for everyone? You have to be kidding to think that such an idea could be implemented. People wouldn't stand for it.
The beauty of remote outposts... is that they are remote. Getting to them takes time. Any disease which cannot remain dormant for the entire duration of the trip is very likely to trigger quarantine measures (or better) at the far end.
Mars isn't such a bad place for humans, having the CHON necessities in vast quantities compared to any other likely spot. Still, it might not be the best place to begin. For various reasons (that I hope to finish blogging about soon) the earth-sun L1 point might be a worthwhile place to start. Yes, there's nothing there but SOHO... yet.
Thanks for the response. I just ran into your blog lately and find it a good read. thank you for you efforts.
As for 2050 for rejuvenation. That's going to be tough. I'll be 88 and the oldest of all my predecessors have yet to make it past 87. My 3 year old will be 49 so should make it. Should be interesting - might have to do the cryogenics avenue, though that seems even more far-fetched than slowing human aging. Having it come earlier would be much better though!
As for Mars: George why would the presence of life have any impact on the decision to colonize Mars? If the human race plans to step out into space, it will make the colonization of the New World look like it was done by the Sierra Club. If life is found on Mars that would be great, but its probable extinction when the colonists arrive and terraform should not be part of the decision. We can save them in zoos if need be.
You can make a very good argument that only intelligent life needs to be avoided (especially the ones that can eliminate us). I always remember that its better to be the Conquistador than the Aztec....
I think we're getting it wrong on the premise. I don't think this will be an effort funded by governments, necessarily. My dream of space exploration has nothing to do with NASA or nation states. I dream of space exploration working the same way the Internet works: with a group mind constantly seeking out answers and approaches. I don't necessarily think the US will lead in this. By the way, I think solar sats will build the infrastructure that will take us to MARS and also prove profitable. As far as those silly people Rutan and Branson, i think their plan is to first make low orbit trips profitable, then low orbit hotels profitable,then trips to the moon profitable...that kind of thing. Ask them again in 20 years...
I also think you're looking at what NASA could or should do. When you should be asking what will Brazil, India, China, Japan and the EU do, not to mention possibly seven to eight viable private space firms? When you look at that way, and you assume that Rutan may have figured out a way to get to low orbit cheaply, Mars isn't just likely, it's inevitable...
We aren't going to have a self-sustaining Mars colony in the next few decades. If the continued existence of the human race requires such a thing before then we are in trouble in terms of species survival. Though I do not care about the cause of allowing some small group of humans to survive on Mars while the rest of us die. I would rather focus efforts on preventing us all from dying right here.
Cities and isolation: Yes, people are generally not willing to do so much to isolate themselves. But the taxpayers are also not willing to fund the creation of a Mars colony that will possess enough equipment hat it will be able to sustain itself once established. So you are comparing one unrealizable alternative with another unrealizeable alternative.
Governments are currently unwilling to fund a big push to Mars. As the baby boomers retire and caring for them requires tax increases and cuts in other areas of spending the US government and other Western governments will become even more unwilling to fund a Mars colony.
Keep in mind that a Mars colony would be many times more expensive than a Mars mission and the mission can't even get the funding required.
My take on the Mars colony boosters is that they are just fantasizing. I give far better odds for a political coalition building to fund a serious effort to stop and reverse aging than I do for establishing a Mars colony in the next 30 years.
Mars is inevitable? Not if the human race wipes itself out. But otherwise, yes, I agree. Technology wil eventually advance to the point where the cost of a Mars mission and Mars colony will fall by a few orders of magnitude. Then the Mars colony will be established by sending lots of robots to do all the initial work. But down here on Earth for a few decades to come many technologies will be advanced in order to solve problems on Earth and that desire to solve problems on Earth will be what eventually makes a Mars mission and a Mars colony possible.
I think the Mars colony people really think they are going to go! The people who worked in the dome in New Mexico (forgot the name) truely believed they would be selected for the first deep space mission. It's a religion. The fact that they are msotly in their 20-30s and don't realize that if a colony project is started now that it will be their KIDS (and only if they are selected from millions of potential colonists), not them who would go. They don't understand that they have a better chance of playing in the NBA than going to Mars. But its a religion - not based on reality.
Unless true aging prevention comes along the best chance for anyone over 20 to get into space will be a Rutan type tourist. If you are 40 forget it.
"How do you know that lenses would be cheaper than mirrors? My guess is the mirrors could be very thin.
I see both lenses and mirrors as problematic due to small asteroid hits. The area they'd need to cover would be very large."
Clearly, any kind of physical surface for this application would be in constant danger of destruction by space debris. Of course, the obvious solution is to use a non-physical system. Today's FuturePundit post brings up the thought of E-M fields deployed by a superconducting wire. Similar ideas have been proposed for solar sails. A solar sail that has only a mast can't be ripped to shreds. So in answer to your question...the reason refraction would be cheaper is because light could be refracted at Mars by a very strong magnectic field. Of course that has all kinds of problems in it. Either that, or something similar. Perhaps a cellular system of closest-packed mylar and an automatic patching system.
"I'd like to see some physics on the amount of additional energy we'd need to either produce in fusion reactors or funnel toward Mars with mirrors or lenses to warm it up high enough to make it livable for humans."
"The energy...is approximately 2.9kw− hr/m2 for SR1[Earth] and 2.1kw−hr/m2 for Sojourner[Mars]." [from http://www.kipr.org/papers/iros03.pdf]
Mars receives at least 500 W/m^2 of solar flux. [http://ralph.open-aerospace.org/solar/ares/report/sumrep2.htm]
Earth recieves 1372 W/m^2. [from my atmospheric physics textbook]
So that extra 872 Watts per square meter is one heck of a lot of juice.
Mars 3,393,000 meters radius, cross-sectional area: 3.617e13 m^2 --> 1.808e16 W of solar flux (Joules per second)
Calculating how many watts Mars needs to receive in flux to get the same energy per square meter as Earth:
1372 * 3.617e13 = 4.963e16 W
and the difference between what Mars gets from the Sun now and what it needs is 31,550 TW.
So let me clarify...
Mars needs 31,550,000,000,000,000 Watts to have the temperature of Earth, and thus the material properties of our home planet (liquid water etc). Thats a LOT, especially when you consider that currently the world uses about 4 terawatts to meet all its energy needs.
So...for the purposes of terraforming (and the obvious conclusion is..."I'd rather live in a dome!") fusion reactors or any other kind of energy generation won't cut it. That is just so much! Dang!
And at 500W/m^2, that means that we would have to set up
3.155e16 / 500 = 6.31e13 m^2
63,100,000,000,000 square meters of extra flux. (all told, more than the cross-sectional area of the earth)
It seems to me that the only way to feasibly heat mars is with 100 satellites each having a radius of 450 km.
"But if the intent is to create a non-Earth habitat where lots of people can live then aren't L5 and moon colonies more cost effective?"
Costs of maintenance being what they are, it seems to me that the cost of an enourmous system of distributed mars-synchronous flux enhancing satellites would be cheaper both to set up and to maintain than any of the orbital station or lunar base scenarios. The difference being primarily in the fact that an appropriately heated Mars would be habitable even in the event of numerous breakdowns in the satellite system, and that the freedom of unconfined civilization on Mars would be able to repair the systems themselves much more quickly than any repair mission to L5 orbit would be able to do anything. It all comes down to resources. The cost of setting up on Mars is significant and time consuming, but once done, the resources available are plentiful and the society could be self-sustaining. Any L5 or Lunar colony would in essence be a space station relying on Earth for resources (since the moon has only He-3) and Mars could provide its own.
And whatever you say about what needs to be done first (and I agree with you by the way), the goal is of course to settle mars as a habitable planet. We have run out of room to expand, and we all need and want more. Every teenage boy in this world that's ever heard of interplanetary travel wants to be a galactic homesteader. (I can't wait to wear a womp-rat skin hat!)
Always expect the unexpected. Don't be dull-witted and merely extrapolate present trends into the future. Just because everybody else does. Based on probabilities from what we know now, billions of people are likely to die from religious/ideological violence in the next few decades. The technology of mass murder is getting too effective and accessible to suppose otherwise.
Technologies for space habitation are less clearly inevitable, but Star Trek etc. penetrated the minds of a lot of smart people. Rutan and his colleagues/competitors are not the ones who will turn the corner. But they certainly inspire the people who will. It's the idea that has to be out there in enough smart minds to have a chance to fuel the breakthroughs.
Just about every step toward that goal has to find a way to make a profit. The gov. can't afford to freight this one and is too stupid anyway.
On second thought...inhabitants of low-g worlds are at such a disadvantage...I never wanted to live on mars anyway.
gustable, learn some physics! Magnetic fields do not affect the paths of photons in vacuum.
The density of meteoroids is very low. The Long Duration Exposure Facility (LDEF) was in LEO where there is plenty of fine space junk as well as meteoroids, but its aluminized Mylar thermal blankets, while holed, were largely intact. Mirrors could easily lose 30% or more of their area without falling apart, and that amount of damage would take a long, long time to accumulate.
I know I'm dipping into sci-fi here, but sure they do. Why can a tokamak mag field around a fusion generator keep all those excited particles at bay? If a mag fiueld of that strength can keep all that e/m rad out, it can surely affect light...or perhaps not. But that doesn't matter because my scheme will surely work, if what you said about the LDEF is true!!
I'll be rich!!
The magnetic fields in a tokamak are not confining photons, they are confining a plasma of charged particles. Magnetic fields act on moving charges by the vector cross-product of charge and velocity: F = B × V
"So...for the purposes of terraforming (and the obvious conclusion is..."I'd rather live in a dome!") fusion reactors or any other kind of energy generation won't cut it. That is just so much! Dang!"
Why won't fusion generators cut it? I can imagine fusion generators providing 35,000 terawatts of power.
"A one-gigawatt fusion plant would need about 100 kilograms of deuterium and three tons of lithium to operate for a year, generating about seven million MWh of electricity."
If hydrogen-boron fusion could be used, that would be even better: