Talk:Terraforming of Mars/Archive 2

Questions to answer

I don't know where to direct these questions, but the answers might be interesting to add to the article if someone wants to research them. Chadlupkes 19:51, 24 May 2006 (UTC)

• How much effect does the size of Mars have on the density of the atmosphere? If we did the work to increase the atmosphere, how much would it lose by simply not being able to hold the gasses on the surface? Now, given the density difference between Venus and Earth, perhaps some gases could be more able to increase concentrations than others. I know that some gases like Helium and Hydrogen have the ability to escape our own atmosphere, so at least Hydrogen would need to be combined with Oxygen in water molecules to be able to make them heavy enough.

How about looking into: http://sciyo.com/articles/show/title/potential-of-the-solar-energy-on-mars where me and the main author look into exactly that, among other stuff. You also have some references in that article towards other articles discussing this exact same thing.204.17.179.2 (talk) 21:20, 31 March 2010 (UTC)

• There were some tests done in the laboratory here on Earth to see what kind of terrestrial life form would be able to survive and thrive in that type of environment. Is there any information in Wikipedia about those studies?

• i dont know where to put this but shouldn't the artical explain how they would get oceans going if mars was terraformed?

Add your own questions...

^I think it explains, but if not, look at my link above. There are NASA studies. We found water ice there, enough to make an ocean if we melt it all by heating the atmosphere up. Therefore, we heat the atmosphere, we solve the issue with the water.204.17.179.2 (talk) 21:20, 31 March 2010 (UTC)

It's not only Venus that has a higher atmospheric pressure than Earth; Titan also has a higher atmospheric pressure than Earth, despite having a surface gravity less than Mars's. I have an equation in one of my books for the (simplified) halflife of an atmospheric gas based on molecular weight and surface gravity; I'll find that. Oxygen and nitrogen have much longer persistence times, being in diatomic gas form, than water vapor, but the persistence time for any gas is long enough that the required replacement rate to maintain a steady state would be minuscule compared to the rate at which it would have to be added in the first place for a reasonable terraforming program. - Reaverdrop (talk/nl/wp:space) 20:01, 24 May 2006 (UTC)

• A question i have is the cost, are there any estimates out there on how much terraforming mars would cost?Crd721 06:48, 18 August 2007 (UTC)

It's almost impossible to make an accurate estimate - even to within a couple of orders of magnitude - at this stage, and the answer is probably not particularly meaningful. At the most basic level, we don't know how big the world (Solar System?) economy will be by the time terraforming is attempted. Nor do we know which technologies will be available and effective for the job, if it's attempted (obviously, being able to use living things as part of the process reduces the cost greatly). And are we assuming a pre-existing human Mars colony, or starting with a blank slate? --Robert Merkel 04:47, 30 August 2007 (UTC)

If you have one planet to start with and two at the end, you probably turned a profit ;) 70.15.116.59 15:55, 14 November 2007 (UTC)

It may be more meaningful to talk of costs in terms of energy. For example, if the delta-V energy required to push ice/ammonia/whatever from other orbits requires a mass of nuclear fuel greater than all of the payloads we've ever gotten off of earth to date by a factor of, say, 10, then that may be more meaningful than 92.6 yottadollars in the year 2314. 206.124.146.40 (talk) 03:35, 24 July 2009 (UTC)

I could be wrong, but i think its 2 million dollars per second. At least thats a good rough estimate.

• I'd like to see calculations of the volumes of gas required to build an earth-like atmosphere on mars. Specifically, what volume of CO2 would be required, as compared to the volume currently on mars, and what volumes of oxygen and buffer gas would be required? Perhaps compare these values with volumes likely to come from the various gas sources listed in the article. The whole global warming/climate change issue here on earth has shown that we are clearly capable of manipulating an atmosphere on a global scale, but it would be very good for this article to give numbers that put in to perspective exactly how much effort would be required to build an atmosphere nearly from scratch. ~ Harperska 17:25, 11 November 2007 (UTC)

• Terraforming Mars sounds nice, but there IS a Reason why the water disappeared. It would be still there. There was a theory that Mars Gravity cant hold the Water. is this true? Christian Kiss —Preceding unsigned comment added by 141.70.92.23 (talk) 11:03, 14 November 2007 (UTC)

• a lot of this is actually addressed in the article, albeit sloppily. Loss of atmosphere -- which includes water -- is a function of gravity (retention) and impact of the solar wind (erosion) plus atmospheric heating (insolation -> expansion). Someone with the right sort of knowledge, or a lot of patience, could knock off a loss rate figure, and thus a replacement-needed figure -- you'd have to assume a human-livable temperature at ground level, of course. Larry Niven did the math for the moon; it turns out that if we really wanted to, our closest heavenly neighbor could have an atmosphere and surface water! NASA actually did an estimate for the time needed to terraform Mars (wish I could find it!), for that matter -- and arrived at a figure of between 100 and 1000 years, which I see as a sort of official way of saying "we really don't know enough". Dismalscholar (talk) 09:55, 16 January 2008 (UTC)

• In the "Why terraform?" section, it says that the reason for terraforming Mars and migrating there is that the sun will grow too hot in hundreds of millions of years. This is the only reason listed for terraforming Mars. But hundreds of millions of years is an extremely long time and it's likely that human life on Earth won't last that long. There are many things that could wipe out humans at any time, such as overpopulation, famine, disease, asteroids, meteorites, climate change, or nuclear war. I think it should be mentioned in the article that, besides the sun growing too hot, there may be other, much more pressing reasons for colonizing Mars. —Preceding unsigned comment added by 70.44.78.154 (talk) 17:57, 2 April 2008 (UTC)

• I would like to see a comparison of surface radiation levels after transforming to an earth-like atmosphere. There is solar AND ALSO cosmic radiation to account for, and without the magnetic field, conditions could be quite nasty. I'm under the impression that radiation levels increase quite rapidly to lethal levels as you leave the Earth-Moon system, and without a magnetic field, I can't see why Mars would have a much lower level of radiation then the space around it. If I can find information on this, I will add it myself. naturalnumber (talk) 18:52, 15 January 2010 (UTC)

I have added some information on cosmic rays, and linked to another wiki page with even more information. It shows that they do pose a serious risk. I am not sure about solar radiation yet. naturalnumber (talk) 21:08, 15 January 2010 (UTC)

• Regarding the section "Magnetic field and solar radiation", specifically the statement "Without a magnetosphere, the Sun is thought to have thinned the Martian atmosphere to its current state;"... How would the atmosphere form in the first place, given these factors preventing a sustainable atmosphere? Basically, the article reads like there was once an atmosphere that was at some point "thinned" by solar radiation. How would an atmosphere accumulate under these conditions? Eckm (talk) 22:49, 31 March 2010 (UTC)

• Possible Answer. Early on in the development of the planet the planet could have had magnetosphere.. I think I once learned that because Mars is smaller the core cooled down quicker than that off the earth. In those early times a 'moving liquid' core could produce a magnetic field. On top of that plate tectonics also favours CO² sequestration. — Preceding unsigned comment added by 2A02:2C40:400:0:E5DF:627C:F729:4FBF (talk) 02:32, 13 January 2015 (UTC)

• Regarding the section on sublimating the southern dry ice cap, I think it dates from a time when we thought the icecap was entirely made of dry ice and not just 8m deep as we know now (wikipedia on martian polar ice caps). Doing the math, we have (with the northern one added) a volume of 6409 km3 of dry ice, let's say at an average density of 1.5g/cm^3 that makes a mass of 9.6*10^15 kg, adding that to the atmosphere wich has a mass of 2.5*10^16 kg and raising the temperature to 230K average globaly (arbitrary value to say we have melted dry ice and not water ice) with the current volume of the atmosphere, I find out that it raises the pressure from 0.63 to 0.87 kpa. So very far from the promised 30kpa. Then I am just a hobbyist, not a real scientist, so if someone who actually know all that stuf better could check the calculations, that be great. — Preceding unsigned comment added by Kelewan (talk • contribs) 12:43, 3 August 2014 (UTC)

Next section: Adding Life

I think the next section we should add to this article is one about what it would take to add life to the Martian environment. But the only thing that I've seen on the subject is in Sci-Fi. Who has some true research done on this subject? Chadlupkes 19:55, 24 May 2006 (UTC)

This is a pretty old comment but I think still relevant. There is mention of the addition of extremophiles, but I think if anyone finds any valid speculative sources about more complex life forms in relevance to terraforming I think that would make an interesting section. Eddie mars (talk) 15:50, 6 March 2010 (UTC)

I don't have a reference at hand but it will probably be an algae that thrives in high CO2 gas environment and produces O2 as a biproduct; that is how multicellular surface life developed on Earth. However, to be done on Mars, something has to be done to protect it from ionizing radiation from space, like growing them on vented caves. --BatteryIncluded (talk) 16:39, 6 March 2010 (UTC)

Certain strains of the extremophile cyanobacteria are candidates; here are some research papers you can use and quote:

• A primitive cyanobacterium as pioneer microorganism for terraforming Mars.
• Terraforming Mars: dissolution of carbonate rocks by cyanobacteria

Also, here is a bit on multicellular plants for later stages of terraforming: Technological Requirements for Terraforming Mars

I believe the absence of quality references of animal use in terraforming is that that their introduction will do very little to help the build up of a benign atmosphere, however, in the later phases of terraforming, "farm animals" (herbivores) could be a valuable food and fertilizer source for the human colony. If all phases were to be successful (millions of years required) there may be attempts to create some kind of balanced biosphere, where a very large biodiversity and ecosystems would be required. If this proposed section is added to the article, there must be mention of ensuring that the seasonal changes are within the livable tolerance of the organisms introduced.

Cheers, --BatteryIncluded (talk) 03:00, 12 March 2010 (UTC)

Duration of Terraforming

How much time would the terraforming of a planet take? -- 86.121.56.174 16:37, 11 September 2007 (UTC)

Better set this one aside for a 3 day weekend, just to be safe.

They predict something around 50 years to just establish a colony, and millions of years for an atmosphere. —Preceding unsigned comment added by Roboy600 (talk • contribs) 04:42, 22 December 2007 (UTC)

Probably a lonnnnnnng time.19:53, 29 September 2007 (UTC) —Preceding unsigned comment added by T.Neo (talk • contribs)

For Mars, it would probably take somewhere between 400 and 1,000 years. Venus would probably take at least twice that. Elsewhere, low surface gravities would allow atmospheres to escape fast enough to make it not worth the effort. 70.252.172.50 (talk) 15:32, 27 December 2007 (UTC)

I understand it could take as little as 1,000 years for a terraformed Mars to lose its atmosphere. That may sound like a long time, but humans as a species may be around another billion years or more. Can we afford to throw away a planets worth of breathable atmosphere every thousand years? There's only so much available.173.60.95.232 (talk) —Preceding undated comment added 23:13, 31 July 2011 (UTC).

Yes, Zubrin (as referenced in the lede) estimates Mars could be warmed and "atmospherized" in 50 years enough for plant life, with the creation of enough oxygen for humans to breath within 900 years, mainly done by the plants imported. --Roentgenium111 (talk) 14:54, 29 August 2012 (UTC)

Actually latest estimates by the Mars Society are 1000 years to get as far as plant life and reasonable CO2 atmosphere so that you only need an aqualung type oxygen breather instead of a spacesuit - but that's not including oxygen, which would take more millennia, with Chris McKay estimating 100,000 years if done using plants. That's because - to make oxygen using plants - the photosynthesis cycle has to take CO2 out of the atmosphere - and turn it into organics - that's how it works. So you then have to build up a layer of several meters of organics over the surface of Mars before you can get a significant amount of oxygen in the atmosphere - even though it comes from splitting water. Also because of the lower gravity, Mars needs more actual mass of oxygen, nearly three times as much, for same atmospheric pressure. So that's obviously going to take a fair time to happen. His 100,000 years I think would be speeded up by a factor of 2 to 50,000 years if you have giant mirrors giving same solar radiation as Earth. If it worked that is of course. And you also have the problem that CO2 is poisonous to humans in high concentrations even when you have enough oxygen to breathe - so you need something else like Nitrogen as well as a buffer gas and Nitrogen is in short supply on Mars. Overview of their ideas here National Geographic - The Big Idea Robert Walker (talk) 17:23, 1 August 2014 (UTC)

Permafrost sea level?

The Main Page describes the featured picture at the top of this article as representing the sea level on Mars if all the existing permafrost melted. I know that estimates of the depth of ice at the polar caps have increased greatly in recent years, but I thought we were still far short of such vast oceans. Could someone provide this information in the article? 70.15.116.59 00:41, 14 November 2007 (UTC)

Reasons for terraforming

This section needs expert attention. There are several more important reasons than a scenario that happens millions of years in the future. In fact, using that is almost an argument NOT to do terraforming -- there are many more fruitful, immediate, and cost effective space projects (let alone terrestrial ones). The factors considered by NASA and others are documented, it won't be difficult to find solid references.Piano non troppo (talk) 13:32, 6 September 2008 (UTC)

Same here, surpopulation and lack of ressources causing planet colonisation is a mith. Lack of ressources could impeach it in fact. This passage need correction.193.52.245.6 (talk) 14:26, 15 July 2010 (UTC)

I agree about the Sun argument. Surmising that the human race survives that long, Mars wouldn't be all that habitable during the Suns death and most certainly not after. As we're talking billions of years in the future it is not unreasonable to assume that humans, if they still exist, would've left the solar system all together, let alone Earth. Jamiepgs (talk) 19:35, 10 August 2010 (UTC)

Wouldn't it be easier and cheaper to build O'Neill colonies or space rings instead?173.60.95.232 (talk) —Preceding undated comment added 04:25, 1 July 2011 (UTC).

We won't know for sure until we try both. —Tamfang (talk) 07:25, 1 July 2011 (UTC)

It should be easy enough for someone with the appropriate training and experience to compare the two. Terraforming Mars will probably take centuries to complete. An O'Neil cylinder could be built in less than a decade. Mars contains enough raw material to build the equivalent of thousands of Earths.173.60.95.232 (talk) —Preceding undated comment added 23:07, 31 July 2011 (UTC).

The asteroid belt contains enough material to build Stanford Toruses with a 1000 times the surface area of the Earth. That's a calculation that goes back to the 1970s at least and is the reason they focused so much on O'Neil Cylinders and Stanford Toruses in the first place. So you don't need to mine Mars. Indeed you can start with the Moon, a small bulldozer, for a year or two and a mass driver would be enough to get all the materials for a Stanford Torus's cosmic radiation shielding, population 10,000. Or a single 300 meter sized NEO - some of those are more accessible than the Moon for delta v. See Asteroid Resources Could Create Space Habs For Trillions; Land Area Of A Thousand Earths.

My article on Trouble with Terraforming Mars might be a useful source for ideas and material - it's not peer reviewed so you can't cite it directly here - but has lots of links to other material. I'd be interested to help with the article - but I'm hesitant about editing Mars articles since an episode last year when all the material I contributed to the Mars section of wikipedia was deleted over a period of a few weeks by a couple of editors who felt that it was inappropriate to mention these issues in the colonization sections of the encyclopedia - and I got labelled as a troll for trying to defend my edits. (Though it was all well cited, my best attempt at summarizing published research - and whether I did or not - certainly I had no intention of including any of my own opinions in the encyclopedia).

But anyway you are quite right - is easy to look up the figures. The 1970s estimate was, I think around 30 years to build the Stanford Torus - with 1970s technology - something like that, might be 40 years, would need to look it up. The estimate for terraforming Mars by the Mars society is about 1000 years - and that's for a CO2 atmosphere -another few extra millennnia to get the oxygen levels up (Chris McKay estimates an extra 100,000 years) - and that is if it works - and requires sustained high technology civilization - only way to live on Mars is in spacesuits throughout the process etc and requires giant telescopes in orbit, greenhouse gas factories etc etc - with no guarantee that it will work - as after all it took millions of years on the Earth and are many differences also showing that what works on Earth would probably not work unchanged on Mars. So - seems to me is obvious which of the two is easiest to do... Robert Walker (talk) 16:29, 1 August 2014 (UTC)

Removed some sentences.

I have been unable to find information backing this statement up, feel free to do so if you know more about it, I have removed it completely as it seems unnecessary at this time.

• "However the results of studies announced in 2008 show that due to tidal interaction between the Sun and Earth, Earth would actually fall back into a lower orbit, and get engulfed and incorporated inside the Sun before the Sun reaches its largest size, despite the Sun losing about 38% of its mass. Therefore, it is a question still unanswered."

Eddie mars (talk) 20:19, 5 March 2010 (UTC)

"About 7.6 billion years from now, the Sun will reach its maximum size as a red giant: its surface will extend beyond Earth’s orbit today by 20% and will shine 3,000 times brighter.[3]"

In the second article, the sentence is present "About 7.6 billion years from now, the Sun will reach its maximum size as a red giant: its surface will extend beyond Earth’s orbit today by 20% and will shine 3,000 times brighter.[3]". Though it has been properly cited, 'extend beyond earth's orbit by 20%' is not inaccurate, but more properly described as biased, or debateable. I have done alot of research, and way too many sites have come to cite them. But my point: chances are the person who wrote this only used one site to get this information. My results have claimed differently from 'barely engulfing venus' to 'fully engulfing mars', therefore that statistic should be changed to a wider range. (I haven't changed anything in the article though, I'll leave that to someone else)—Preceding unsigned comment added by Ogel6000 (talk)04:05, 11 October 2010 (UTC)

signature information added by Fartherred (talk) 17:26, 11 October 2010 (UTC)

ocean

It has been found that significant amounts of water are stored in the south pole of Mars, and if all of this ice suddenly melted, it would form a planetwide ocean 11 meters deep.

Well, not exactly. Assuming that means that the volume of polar water is 11 meters × the surface area of Mars, what you'd get is more like a 33 meter ocean in the north! What's a good way to reword this? —Tamfang (talk) 00:58, 6 November 2010 (UTC)

External Links need to be updated

Most don't work or definitely are not high quality. — Preceding unsigned comment added by 208.88.175.43 (talk) 17:51, 25 August 2011 (UTC)

quite a web

I worked on this article once long ago, and must say it's better since I last dropped in. With my efforts to redo it constantly going into my trash bin as unsatisfactory, I've decided the entire article needs expert attention. The reason is that terraforming a planet such as Mars isn't going to be a linear progression, but a complex web.

People think in terms of warming Mars first, or adding an atmosphere first, and then discuss the magnetic field after, but those are woven together, as is the topic of life. If we start warming Mars, that alone will change the atmosphere, and may end up driving desirable gases off the planet. To keep that from happening, other gases have to be added right from the start, to keep the desirable ones at lower concentration. But we don't know how stable any of that will be because it will change the moment any life is dropped in, whether blue-green algae or molds or whatever. Just as a good atmosphere is necessary to sustain life, a biosphere is necessary to stabilize the atmosphere, and the temperature.... and that all depends on the gravity and the magnetic field.

The article mentions making an artificial magnetic field, but without any hint of an engineering solution to that, it's nothing but science fiction. Without that magnetic field, it just might be the case that none of the above efforts would have a point to them at all. The Star Ship Enterprise might just reconfigure its main deflector dish and liquefy the core and set it spinning, but for a Wiki article there has to be at least some credibility, something that can appeal to current engineering and/or theory for its foundation. Just as a silly example, someone might say that the solution to warming up Mars is easy -- just move it fifty million miles closer to the sun. While that's simple in concept, it's ludicrous as anything but science fiction for the time being.

At any rate, to even go ahead with terraforming is going to have to assume the magnetic field problem has been handled. Then, atmosphere, water, warmth, and life go hand in hand in a careful balancing act.

To add to the mix: do we need the technology to retrieve asteroids in order to do this? the ability to catch comets and steer them? Dismalscholar (talk) 03:07, 20 December 2011 (UTC)

Additions to the article can be improvements if they are reliably verified. For instance the statement: "Without that magnetic field, it just might be the case that none of the above efforts would have a point to them at all." It might be true. When one says "might" it opens the door to a large number of true statements of limited value. If there is a source for that it might be worked into the article. Fartherred (talk) 18:47, 20 December 2011 (UTC)

Incorrect marking of dead links

I discovered that item 15 in the citations list, http://science.nasa.gov/science-news/science-at-nasa/2003/29dec_magneticfield/, was marked as a dead link, but that it was accessible. I corrected this. However, I also updated the "accessdate" to mark the date that I confirmed the citation was accessible. Is this correct, or should I have left the accessdate alone? --Filksinger (talk) 07:53, 17 March 2012 (UTC)

@Filksinger:, yes, that is the correct process. It shows the date accessed by the last editor who confirmed the source. N2e (talk) 00:39, 14 September 2014 (UTC)

This article is missing a major section: Global Active Magnetic Shielding

The major objection to any discussion of terraforming Mars is that Mars lacks a magnetosphere. Subsequently, Mars cannot retain an atmosphere since it has been thought that the dominant non-thermal atmospheric loss process on Mars is due to solar wind. As such, this article is not complete without a discussion of Global Active Magnetic Shielding. NASA is currently researching active shielding for spacecraft and primary candidates for active shielding include, but are not limited to: confined and unconfined magnetic fields requiring super-conducting magnets, plasma shields, and electrostatic shields. Proof of concept for the feasibility of electrostatic active shielding has already been established. Last year, the Johnson Space Center published their final NIAC phase one report, "MAARSS: Magnet Architectures and Active Radiation Shielding Study" (http://www.nasa.gov/offices/oct/stp/niac/westover_radiation_protection.html). Planetary-sized magnetic shielding is also supported in a report by the National Institute for Fusion Science of Japan, "Feasibility of Artificial Geomagnetic Field Generation by a Superconducting Ring Network" (http://www.nifs.ac.jp/report/NIFS-886.pdf). This report states: "The approach of generating artificial geomagnetic shield is also applicable to the moon and other planets such as Mars, where there is no or thin atmosphere and small planetary magnetic field, in order to support the establishment of habitable bases, should the need arise." My main point here is that the lack of a magnetosphere is not necessarily a show stopper for terraforming Mars.

I am aware of the magnetic umbrella mechanism in the southern hemisphere of Mars (http://science.nasa.gov/science-news/science-at-nasa/2008/21nov_plasmoids) (http://adsabs.harvard.edu/abs/2008AGUFM.P13B1320B). It could be that these plasmoid losses have been the major mechanism of atmospheric loss in Mars' history. Certainly this needs to be researched and a means to counter these local magnetic fields would need to be developed if any terraforming attempt is to be successful. Hopefully MAVEN will provide us with some answers. Nydoc1 (talk) 23:53, 12 February 2013 (UTC)Nydoc1

Speed of Atmosphere loss relevance to human civilisations

Is there really a need for magnetic shielding?

This article "https://www.nasa.gov/press-release/nasa-mission-reveals-speed-of-solar-wind-stripping-martian-atmosphere" suggests that "MAVEN measurements indicate that the solar wind strips away gas at a rate of about 100 grams (equivalent to roughly 1/4 pound) every second."

If humans managed to create a thick atmosphere on Mars, the half life time of the atmosphere could be in the time scale of a Billion Years. This would not be considerably relevant for humans in the near to mid future. — Preceding unsigned comment added by 131.176.243.9 (talk) 10:29, 8 January 2018 (UTC)

Since the entire concept is completely impossible for mankind to ever achieve, I wouldn't worry too much over it in the article.104.169.16.173 (talk) 17:30, 17 February 2018 (UTC)

Out of date atmospheric composition

I believe that the table containing the percentages of gases in the atmospheres of Mars and Earth uses old data, and should be updated using the data from Curiosity rover obtained in September. — Preceding unsigned comment added by 31.205.67.64 (talk) 23:38, 5 November 2013 (UTC)

 Done — Reatlas (talk) 16:07, 6 November 2013 (UTC)

Article is missing lots of references and citations

An editor has placed (in 2013) an article-level tag on the article that there is much " unverifiable speculation and unjustified claims." In my view, this is correct, as their are entirely too few sources provided for the statements made.

I have started to remove some of the specific unsourced statements: those that have been challenged for more than a couple of months. I have also specifically challenged other statements and requested citations. Over the next months we should be able to add reliable source citations for that which editors would care to source, and then begin to remove the rest, as it is either original research or simply not verifiable in a reasonable period of time.

At that time, we'll be able to remove the top-of-article tag, and the article will be cleaner and better per Wikipedia policy. Cheers. N2e (talk) 00:36, 14 September 2014 (UTC)

Electrolysis

One of the "citation needed" notes is ludicrous: no citation is needed to support the statement that with water and electricity electrolysis could be done on Mars; sixth-grade chemistry is not different on another planet. Dismalscholar (talk) 07:01, 4 June 2017 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Terraforming of Mars/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

141.151.15.254 (talk) 19:34, 11 December 2007 (UTC) If there is existing life on Mars,then further study would have to be done before terraforming could proceed. Jerry Lehane III 141.151.15.254 (talk) 19:34, 11 December 2007 (UTC)

Last edited at 19:34, 11 December 2007 (UTC). Substituted at 07:49, 30 April 2016 (UTC)

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