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#1 2014-04-16 16:00:24

Tom Kalbfus
Registered: 2006-08-16
Posts: 4,401

Martian Canal Highways

This idea came to me as I was driving down a highway. Imagine a paved highway on Mars made of asphalt. There are three lanes going one way and three lanes going the other, and a green space between the two directions on the highway just like on Earth, we also place an equal amount of green space on either side of the highway. So lets assume each lane is 10 feet wide (3 meters). There are three lanes going in one direction of the highway, that's 30 feet, plus we have breakdown lanes on either side, that's 10 feet wide on the inside and 10 feet wide on the outside for 50 feet in one direction, we have a 50-foot wide median and then another 50 feet for the 3 lanes and 2 breakdown lanes going the other direction, and we add 50 feet of green space on either side of the highway, for a total width of 250 feet, and we seal that in a plastic tube that is pressurized at a one-Earth atmosphere mixture of nitrogen and oxygen. to help hold all that air pressure in we place the plastic tunnel at the bottom of a Martian canal that we dig for this purpose, or perhaps we could use a natural river bed that may already exist on Mars for this purpose to save work. We put an outer plastic tube over this ancient river bed or canal and we pressurize to twice or three times the normal atmospheric pressure of Mars, this pressure is still to thin to allow breathing by a normal human, but it will allow liquid water to exist within a narrow temperature range. The atmospheric pressure of Mars is 0.087 psi, so lets triple this to 0.254 psi I think liquid water can exist under these conditions. The pressure within the highway tunnel will be 14.69 psi, same as Earth at sea level. A cubic meter of water weighs a ton under earth gravity and a ton is approximately 2200 pounds. On Mars this same amount of water would weigh 836 pounds. A meter cube of water is about 1600 square inches of a foot print, so divide what a cube of water weighs by the square inches of its foot print and we get 836/1600 = 0.5225 psi, we want to get to 14.69 psi so we divide 14.69 psi/0.5225 psi to get 28.11 meters of water on top of the highway tunnel, subtract half a meter of water to get 27.6 meters of water, the bottom of which equalizes with the air pressure of the highway tunnel. We also have 0.254 psi of compressed Martian atmosphere on top of the canal to allow for a liquid surface on top. So each cubic meter holds 1000 liters of water. Since the highway will be 250 feet wide with all the green space, each 10 feet translates to 3 meters. 25 * 3 = 75 meters, so a section of canal that was 75 meters wide by 75 meters which is 27.6 meters deep would contain 155250 cubic meters of water or 155,250,000 liters of water. Since we need to keep the interior of the highway tunnel habitable for humans, it needs to be heated, this would mean that some of the water above would be liquid but as we got closer to the surface in would be frozen most of the time, assuming we have some decent insulation of the tunnel walls. The plastic should be clear to let in sunlight and the 27.6 meters of water should also be clear to let in sunlight so it filters down into the highway tunnel below. Besides holding in the air pressure, 27 meters of water also makes great radiation shielding, in case of a solar flare. The Tunnels would contain highways that allow the passage of air breathing cars, perhaps hydrogen fuel cell vehicles. electrolysis plants crack the water into hydrogen and oxygen, and the hydrogen is sold in pressurized form at fuel stations placed inside the highway tunnels to refuel the cars inside at need, that way the cars don't need to be pressurized, only the tunnels do and since there is less leakage with less surface area per unit volume than individual cars, this would be a safer mode of transportation that traveling outside on the Martian surface in pressurized vehicles with airlocks.


#2 2018-03-31 03:14:28

From: USA
Registered: 2018-03-28
Posts: 10

Re: Martian Canal Highways

On a slight tangent, does anybody happen to know the ratio at which plants convert CO2 into oxygen?


#3 2018-03-31 08:59:29

From: Chicago
Registered: 2015-12-14
Posts: 276

Re: Martian Canal Highways

It's a bit complicated; even though the (simplified) equation for photosynthesis gives a 1:1 molar ratio for CO2 and O2, net oxygen production via photosynthesis is quite small per plant since most of it gets respired by the plant itself. (Respiration is just photosynthesis in reverse.)

Net Primary Productivity (technically the production of organic carbon, but duly converted since there's a 6:1 molar ratio between oxygen and organic carbon produced it works just as well) on land ranges from less than 48 mol O2/m^2 in the deserts up to more than 600 mol/m^2 in the tropical rainforests, with a typical value of ~360 mol/m^2 in the temperate parts of North America, Europe, and China according to … IGURE6.htm. The concentration of CO2 in the atmosphere is currently around 400 ppm according to Duly converted and spread across Earth's surface area, this gives around 1,960 mol/m^2 of CO2.

So assuming all of the CO2 is used by land plants this gives a ratio of 0.02-0.31 mol O2 ultimately produced by plants per mol CO2, or 0.18 for a temperate climate. On Earth the ultimate amount of O2 that is produced per CO2 is even lower since much of what's given by plants is respired by animals, fungi, or other organisms that don't make their own food(what are known as "heterotrophs"), but on Mars this could perhaps be controlled.

The Earth is the cradle of the mind, but one cannot live in a cradle forever. -Paraphrased from Tsiolkovsky


#4 2018-03-31 11:25:51

From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,035

Re: Martian Canal Highways

This is a serious question? Ok.

IanM gave a good response. I'll give my take. Photosynthesis is a complicated process, I wrote a webpage about it. The page is a proposal to use invitro photosynthesis for life support.

The net reaction is:
6 H2O + 6 CO2 → 6 O2 + C6H12O6

That means 6 molecules of water + 6 molecules of carbon dioxide become 6 molecules of oxygen plus one molecule of sugar. Specifically a monosaccharide: simple sugars. Most common simple sugars are glucose, fructose, and galactose. These are all carbon rings: 6 carbon atoms in a ring. There are other sugars; pentose sugar has 5 carbon atoms in a ring. The most common pentose sugar is ribose, which is a component of DNA. These can be combined: a single hydrogen atom removed from one sugar, a hydroxyl group (one oxygen and one hydrogen) stripped off the other. Then the free bond of one simple sugar binds directly to the free bond of the other. This forms a disaccharide, which means 2 sugar. The "H" and "OH" bond together to form water. Examples of disaccharides: sucrose (white table sugar), lactose (milk sugar), and maltose (malt). Plants can also bond 6-carbon simple sugars into a long chain. Starch is a polysaccharide, meaning it's a lot of simple sugars linked together. Amylose is a long chain of monosaccharides, amylopectin is highly branched. Recent research shows amylose has a little bit of branching too; nature is messy. Starch is a combination of amylose and amylopectin. So the general formula for polysaccharides:
(C6H10O5)n·(H2O) where "n" is between 40 and 3000.

vemsemigma asked the "ratio at which plants convert CO2 into oxygen". By "oxygen", I assume he means O2. Notice combining simple sugars releases water, so the ratio of water to sugar changes a little depending whether it's a simple sugar or complex carbohydrate. However, the ratio of CO2 to O2 is always the same, it's always 1:1.


#5 2018-03-31 17:19:33

From: New Hampshire
Registered: 2004-07-22
Posts: 19,235

Re: Martian Canal Highways

The other part of that question is which plants do the best exhale of o2 rate? As we would want to grow those that transform h20 and co2 into the sugars and air for man to breath at that highest of rates.


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