“The rate of loss of gas today is very low — slow enough that it would take billions of years to remove the equivalent amount of gas that is in the atmosphere,” principal investigator Bruce Jakosky said in an email. There is some CO2 left in the polar ice and in carbon-bearing materials, he added, but not nearly enough to warm the temperature significantly if it somehow was put back in the atmosphere.
“There isn’t a source of CO2 that could replenish the atmosphere — even outgassing of CO2 from volcanoes has got to be incredibly slow today,” Jakosky added. “If we wanted to put enough CO2 into the atmosphere to raise temperatures significantly, it would take something like 10 million kilometer-sized comets (if they were all made entirely of CO2). This is just not feasible.”
I think there are other possibilities (e.g., bombarding it with carbonaceous and other asteroids, and comets, and manufacturing the CO2 on the surface), but largely, I consider the obsession with Mars to be much more romantic than practical, at least as a new earth.
What about when the farmers and ex-penal colony members grab a nuke or two and crack open dormant volcano fields so that James Cameron buys an option to film it?
If I remember correctly we did a homework problem in my astronomy class (400 level) and concluded that Mars is too small to keep it’s H2O. That is, in the upper atmosphere the kinetic energy of H2O was larger than the escape velocity. Thus no matter how much water you dump there it will eventually “boil off”. (too low gravity and too thin for a earth like cold trap) It might take a few years but if you spend all that time and effort to terraform mars, it will just die again in a few 1000 years. Unless you keep importing huge amounts of water. (of course it was just simplified homework problem so the result could be wrong)
Actually, Ryan, once you build the robot ships to bring ices in the outer Solar System to Mars, there is no reason not to keep some of them operational after Mars has been terraformed. The number needed to terraform Mars in a century would be at least 10 times larger than what is needed to balance off your worst calculated loss levels. A major industrial undertaking? Sure! Impossible for a Solar System-wide economy? Not at all.
In general, I do agree with Rand that focusing on any single node in what will be a Solar System-wide industrial economic network is quite foolish, but the technical difficulties of terraforming are way overblown, even by people like Jokasky, who would know better, if he took the time to think about it.
IIRC the half life of water vapor on Mars is in the millions of years. Not large enough on a geological time scale, sure. But on a human time scale, if you can afford to terraform it in the first place then you can afford to maintain it.
Why restrict the terraforming /atmospheric-forming to Carbon Dioxide?
Peer-reviewed science suggests man-made climate change — in this particular case, deliberate and intentional change in a very crappy cold climate to a nice warm cozy one — results from man-made molecules. CFCs. “Freon ™” etc.
https://phys.org/news/2013-05-global-chlorofluorocarbons-carbon-dioxide.html
Now, where one mines Mars for fluorine to make the molecules may be an issue.
But the larger point is that _IF_ one has good scientific theory, big projects become matters of engineering and finance. If one has crappy theory, no amount of money or clever enginering will make much difference. We haven’t got good results from climate theory, so far here on Earth. I see no reason to write-off Mars, now, based on the theories regarding climate and CO2 that, at the moment, prevail.
It’s always been fantasy. Living on Mars will be like living on Manhattan, only nicer. No one talks about terraforming Manhattan, do they? Although now that I think of it…
Terraforming mars is just stupid. IT’S ALREADY A GARDEN SPOT!
No matter where we go, we are going to terraform it one habitat at a time.
If we found mars orbiting another star the morons would already be making plans to colonize it.
Mars is wealth just waiting to be picked. I wish I could live long enough so history will show today to be filled with fools. Actually I don’t have to wait… history already has a long list of fools no different than those of today.
You, terraform Mars by not altering it’s atmosphere.
To create pressure, use water.
On Earth, 10 meter depth of water, makes1atm pressure. Mars 1/3 of Earth gravity, requires about 30 meters depth of water in order to make 1 atm of pressure. And you don’t need 1 atm pressure to breathe- you need at least 2 1/2 psi [1 atm is 14.7 psi].
So if in diving bell 30 meters below surface of lake on Mars, and bell has air in it, it will be about 1 atm of air pressure.
You could leave this diving bell by holding your breath and swimming beneath the bell- and you could swim up or down by 10 meter of depth and experience less pressure difference as you would experience if did the same on Earth [ going 10 meters up and/or down]. And if using scuba or an air line, one do this for indefinite time period.
What is needed for Mars is water- and not very much. Or maybe, Mars has enough to support billions of people. Or more correctly, Mars most certainly has enough, the only question is related to the cost of “mining it”.
It seems mining enough water would be a lot cheaper than the crazy idea of adding enough atmosphere.
All that is needed to “colonize” Mars is about 1 billion tonnes of “essentially free” water. “Essentially free” water would be all the water one could want/need for the same or cheaper cost than whatever the seat cost to get to Mars. Or water at about $1 per lb [or less].
$1 per lb or $2000 per ton or 1 billion tonnes is about 2 trillion dollars of water.
So to start a colony requires about 1 billion tonnes, to have civilization requires trillions of tonnes of water and water need need to cost less than say less than 100 times more than water does on Earth. US uses about 600 billion tonnes of water for it’s 300+ million population per year.And it seems possible to me that Mars could “evolve” to point where Mars water is cheaper than Earth water- for various reasons.
This is the way to go. To get O2 you just add algae.
Another way to go could be to dig a REALLY deep hole, like on Larry Niven’s Canyon.
From Rand’s link
That works out to over 5 million cubic kilometres of frozen CO2. Converted to a gas at 1 atm that is enough to fill the atmosphere of Mars 28 km deep.
I’m not going to try to figure out closer than that – he’s off by at least an order of magnitude without even considering the exponential effect of pressure decrease with altitude.
“…I’m not going to try to figure out closer than that – he’s off by at least an order of magnitude without even considering the exponential effect of pressure decrease with altitude.”
Hmm.
5 million cubic km of frozen CO2 equals about 7.5 million billion tonnes
Or 7.5 billion billion kgs- 7.5 x 10^18 kg.
Mars currently has “~2.5 x 10^16 kg”
Or it’s about 300 times more than it’s got.
If one merely added 30 times more to atmosphere, one could maybe have enough pressure to breathe without a pressure suit.
Or Mars has about 1/100th of 1 atm of pressure. [And about 1/60th of the density- of Earth sea level density- it’s cold and CO2 is a denser gas. Or 1.2 kg per cubic meter vs .02 kg].
So, one breath with 1/3 of 1 atm of pressure.
But the issue was warmth.
I would say that impacting 10 million 1 km diameter space rocks would
add considerable heat to the atmopshere- so say a decade or so of
considerable added heat. And were the impacting to occur within short time period, the temperature could make Venus cool in comparison. But this wasn’t factor considered.
Instead one has delve into the pseudo science of global warming- “the
science of “the science which is settled”.
Now, Mars currently has 28 times more CO2 per square meter area of planetary surface as compared to Earth’s abundance of Co2 in it’s atmosphere.
Or Mars has about 25 trillion tons of CO2 compared to Earth’s global quantity of somewhere around 3-4 trillion tons [or about .04% of Earth’s atm- Earth has 5.1 x 10^18 kg or 5100 trillion tons of atmosphere. Or if CO2 were 1% of atmopshere then
there be more than 51 trillion tonnes of it in the atmosphere but currently it’s about 400 parts per million- less than a 1/10th of 1%.
Since Mars is smaller planet it has 28 times more than Earth per square meter or per square km- and it’s currently not doing much in terms of warming up Mars.
In my opinion if one added 30 times more CO2- and not counting the heat added from the impactors- that it would not make Mars feel any warmer.
Instead I think it would make Mars miserably colder.
Now, dust levels on Mars do significantly affect air temperature.
And if you added 30 times more atmosphere, it’s reasonable to guess one will cause there to be more dust in the atmopshere.
With more co2 and more dust one could have increase in global average temperatures.
So instead of -50 to -60 C global average temperatures, it could be somewhere around -30 C to 40 C global average temperature [mostly due to added dust].
And roughly that’s what I mean by miserably colder.
Now, I skip commenting on whether 300 times more CO2 would make Mars much warmer- I would simply say
say that even adding 30 times 25 trillion tons of anything is rather expensive.
One issue with terraforming planets with lower gravity than Earth is you need more mass/area to get the same pressure. On Mars this could help a bit with warming, since (for a given CO2 partial pressure, assuming an Earth-like overall composition) you end up with a much larger CO2 column density.
If you wanted to terraform the moon, though (assuming leakage wasn’t too fast) I think it would undergo a runaway greenhouse if there were exposed bodies of water.
Apparently there aren’t enough science fiction readers in the space industry anymore. No need to lose atmosphere to out-gassing if you put a roof on the world.
Mars already has more total CO2 in its atmosphere (about 9 times) as does the earth. In fact, per unit area, it has 54 times as much. Adding more would do nothing to the atmospheric temperature. Adding water vapor would. But to achieve a partial pressure of water vapor equal to that of the CO2 present would require getting 5.5E16 pounds of water somewhere.
The mass of the rings of Saturn is estimated to be about 7E19 pounds, virtually all of it water. So taking 0.08% of it would satisfy the goal. Unfortunately, the energy required to get it out of Saturn orbit is about 20,000,000 megatons of TNT equivalent, or 1,000 times that of all the nukes the US and Soviet Union had at the height of the Cold War. It’s also more than 200 times the amount of energy the entire human race consumes annually.
There has to be a better way.
What mars has is abundant cheap iron. That’s how you hold an atmosphere. A plastic sheet would do it in some cases, but you’d almost have no maintenance with iron… it wouldn’t even rust.