Talk:Terraforming of Mars

message: This article does not mention it at all.  This single factor prevents Mars from ever being truly "Earth-like" due to it having only a third of Earth's gravity.  I think the article misses the point and needs to consider the scope and motivations for terraforming.  Humans settling there would have to cope with extremely low gravity.  Weightlessness#Human health effects  Gravity also has as many implications for Mars holding on to an atmosphere as the lack of a magnetic field. --EvenGreenerFish (talk) 02:38, 4 December 2012 (UTC)
replies: text: 3/8 gee, or even 1/6, is a far cry from weightlessness. —Tamfang (talk) 05:12, 4 December 2012 (UTC)
replies: text:  Added (briefly), along with other issues like amount of sunlight Rafflesgluft (talk) 15:01, 26 November 2018 (UTC)
replies: text: I agree that the low gravity may pose serious health issues, but I deleted the multiple statements saying that Mars does not have enough gravity to retain an atmosphere. Such concept is not supported by references and, in the past, Mars did have a thick atmosphere under the exact same gravity force it has today. Cheers, Rowan Forest (talk) 00:03, 6 January 2019 (UTC)
replies: text: Yes, thermodynamics plays a role in addition of gravity to hold on to particular gases. This would require an additional explanation and refs. Cheers, Rowan Forest (talk) 14:37, 19 January 2019 (UTC)
thread_title:  Gravity 

message: There seem to be a lot of artists impressions included in this article showing Mars looking almost like Earth with global oceans. However there is nothing in the article addressing this - it's complete science fiction. I think one image showing an ocean covered planet would be enough, perhaps along with some text saying that this is the kind of terraforming described in science fiction novels but that no proposed or suggested technology exists that would even hope to achieve something like this... and that anyway since the entire surface is toxic, such oceans presumably would be toxic too!
On a slightly different tack, another issue the article doesn't address is that one of the key ideas of terraforming is that a planet can be completely independent and not rely on supplies from Earth. Is it worth having a section on this? We haven't even managed to master sustainability here on Earth where we are overwhelmed with natural resources and natural cycles (water, oxygen, carbon, hydrogen cycles I mean), so I fear we have a long way to go before we can manage it on a toxic and hostile world such a Mars.
Rafflesgluft (talk) 15:13, 26 November 2018 (UTC)
replies: text: I agree in cutting down on those fictional images. Terraforming of Mars is very likely impossible, so any bases on Mars will always rely on Earth. This article can do a better job of stating it is mostly science fiction. Rowan Forest (talk) 15:25, 26 November 2018 (UTC)
replies: text:  Funny that we were both editing at the same time - sorry didn't realise. OK sure - it seems to me that the first image is actually very useful in describing the topic because it shows the concept of terraforming in a single image (albeit using four sub images), but the others are entirely gratuitous and can go. However deleting several images may be contentious so we should perhaps leave this notice here and if no objections in a month or two, come back and delete. What do you think? Rafflesgluft (talk) 15:35, 26 November 2018 (UTC)
replies: text: Well, four nearly identical [sci-fy] images are too much. Hard to argue in favor of keeping them all. Rowan Forest (talk) 16:20, 26 November 2018 (UTC)
thread_title:  Oceans?? 

message: The article currently states:
:Molecular oxygen (O2) only exists in trace amounts as Mars doesn't have enough gravity to hold on to it.
This has been marked as dubious, giving the reason:
:The Wikipedia article Atmospheric escape lists Mars as heavy enough to hold on to oxygen.
There are three reasons I think the dubious marker is in error.
Firstly, the cited article does not "list Mars as heavy enough to hold on to oxygen", quite the reverse. Talking about Venus it notes that "....cause the atmosphere to be stripped almost entirely, much like that of Mars". I assume therefore that the claim is based on the below diagram at the top of the article, which applies only to thermal escape (the article gives two broad categories of atmospheric escape, thermal and non-thermal). In the diagram we can see that Mars sits in the middle of the band for oxygen and nitrogen, which is to say at its current temperature, some of the molecules will be travelling below escape velocity, some will be above it. This is based on the current average Martian temperature. However when the atmosphere is warmer than average due to seasonal and daily variations, a higher proportion of molecules will be travelling above escape velocity (which unlike the speed of the molecules does not change with temperature) and so more will escape during those periods. This is particularly important to note on Mars as the common global duststorms have the effect of warming the atmosphere itself (the dust suspended in the atmosphere is heated by the sun, rather than the ground being heated). I.e. both the diagram and article text support the statement that Mars doesn't have enough gravity to hold on to O2.
Secondly, the other class of escape mechanism (non-thermal) is particularly applicable to Mars where the atmosphere is so thin that when the solar wind is strongest, it blows all the way down to the planet surface. This imparts far more energy to molecules in the atmosphere than from the ambient temperature alone, causing far more of them to exceed escape velocity (potentially even the heavier ones such as CO2).
Finally, regardless of the theoretical side, despite the absolutely tiny amount of oxygen in the Marian atmosphere, enough escapes that we have direct observations of it happening. In fact a diagram recording oxygen escaping is already included in the Terraforming of Mars article:
For these three reasons it seems clear to me that the statement "Molecular oxygen (O2) only exists in trace amounts as Mars doesn't have enough gravity to hold on to it." is not dubious. I therefore propose to remove the dubious marker.
As an aside, the above doesn't take into account the fact that terraforming itself will increase the rate at which oxygen escapes. Currently the rate of escape is very small because there is so little oxygen left. The entire Martian atmosphere is so thin that in some contexts it would be classed as a vacuum. On the surface of Mars oxygen makes up just 0.145% of the 0.087 psi atmosphere (for comparison, on the surface of Earth oxygen is 21% of a 14.7 psi atmosphere). For this reason, terraforming seeks to drastically increase the amount of oxygen in the atmosphere. An increase of around 2.5 million % would be needed to reach Earth like levels. If you double the number of oxygen molecules in the atmosphere, then you'll double the number that are going faster than escape velocity and so double the rate of escape. Terraforming also aims to increase the temperature, which will move Mars to the right on the above diagram and also increase the rate of escape of oxygen (as well as the rest of the atmosphere). Presumably it was back when Mars was warmer and had liquid water on the surface that the majority of the water and oxygen escaped into space in the first place.
Rafflesgluft (talk) 17:56, 28 November 2018 (UTC)
replies: text: Yes, thermodynamics is an additional factor when looking into retention of gases. The article can use a brief explanation on that, along with refs. I assume the latest papers from the MAVEN team have published that, but physics is not my strength. Cheers, Rowan Forest (talk) 14:42, 19 January 2019 (UTC)

text: I'm not sure the diagram shows what you say: (that the placement of mars in the oxygen 'band' shows some will be lost) since eg. earth can hold onto water. Isn't it more likely that the gas boundary lines (not the bands) represent the mean molecular or atomic velocity at that temperature, which we can see is below Mars' escape velocity ? - Rod57 (talk) 13:32, 10 November 2020 (UTC)
replies: text: Hi Rod, well it's possible, however note 1. Mars is losing oxygen. Loss of its oxygen into space has been observed directly, even at current temperatures, heating it up or adding more oxygen will only increase the rate of loss. 2. I believe the Earth is losing water into space, however it's incredibly slow. As the diagram notes, it's only water vapour that can be lost this way, and the vast majority of water on earth is either liquid or solid. The relatively small amount of water that is in vapour form doesn't get very high up in our atomsphere before it condenses - we get clouds - and falls aback to earth - we have precipitation. Finally, volcanic activity is actually adding water to earth's atmosphere all the time. I guess over the millennia we have reached an equilibrium. E.g. see  https://www.thenakedscientists.com/articles/questions/earth-losing-water-space Finally, even if the boundaries represent the mean speed as you say, in fact the speeds of individual molecules are distributed quite widely around the mean, depending on how much energy they lost/gained when colliding with other molecules. For example, please note that Mars is also leaking carbon dioxide (also observed directly - see above), even though the diagram shows CO2 as below the line. Its whole atmosphere is escaping and almost entirely gone, not just the oxygen, water etc. Rafflesgluft (talk) 15:33, 18 December 2020 (UTC)
thread_title:  Dubious - reason for low oxygen

message: This section of the article needs some more development. Redirecting massive asteroids is in itself a questionable feat in the realm of science fiction, as we can't even deal (yet) with near earth asteroids that threaten our existence. Beyond that is the recognized inability of Mars .38 Earth gravity to create an atmosphere of light gases, like oxygen and nitrogen, which are necessary for life as we know it. . There are  light gases in the Earths stratosphere, where the gravity is still almost 2/3rds greater than Mars. And none above it, because there is insufficient atmospheric pressure.  And atmospheric pressure is caused by gravitational pull. Given that Mars has water and that a gravity of .38 Earth, how did Mars with such a low gravitational field even create an atmosphere, much less water and how can it be terraformed? Serious discussion is needed, otherwise the subject is in the realm of  science fictionOldperson (talk) 23:21, 7 October 2019 (UTC)
replies: text: All the article is hypothetical. Redirecting an asteroid cites NASA Ames Research Center (c. 1993). "Technological Requirements for Terraforming Mars". So if you want to find or cite an updated reference then do it. Rowan Forest (talk) 23:40, 7 October 2019 (UTC)
thread_title:  Low gravity and pressure 

message: Cute idea, eh? Should it be incorporated? Jim.henderson (talk) 04:10, 6 May 2022 (UTC)
thread_title:  Elon Musk and 10,000 atom bombs 

message: If I have not miscalculated, the partial pressure of CO2 on Mars is 15 times that on Earth, which means that adding Earthlike air would not suffice; most of Mars's CO2 would have to be removed or converted. Is that right? —Tamfang (talk) 23:15, 25 March 2023 (UTC)
thread_title:  air conversion