Terraform Humans First, Then Mars?

An anonymous reader writes "Related to the future of Mars, NASA released the transcript of an expert panel which debated terraforming the red planet. Planetary scientists including NASA's Planetary Protection Officer, John Rummel, and science fiction writers (Kim Robinson, Arthur C. Clarke, and Greg Bear) chimed in. When asked if Mars should be transformed to a place where humans could walk without life support suits ("naked"), Sir Clarke responded, "Perhaps we should ask the Martians first." Can it be done quickly-- or at all? Is terraforming ethical? If humans colonize, are the colonists on a one-way trip akin to exile?" Read on for a bit more.

"A consensus seemed to be that like waking a sleeping giant, planet building seems possible if oxygen is not a requirement and some microbial life is dormant underground. But the question of making a planet suitable for plants alone seems to span tens of thousands of years. The remaining science fiction notion was terraforming humans, instead of planets, and making us survive on what is now a very alien world."

Comments

Oxygen requirements = yes, Pressure = no.

[WhiteBandit]

I've recommended this on quite a few occasions. Check out Dr. Zubrin's book The Case For Mars. The last half of the book deals with terraforming Mars.

In short, it would be "relatively easy" to create the amount of oxygen that would be needed for us to survive. However, the atmospheric pressure is so low that we will probably never be able to walk around the surface without some sort of protective suit (or oxygen mask).

Re:Oxygen requirements = yes, Pressure = no.

[WhiteBandit]

Not really knowing anything about the subject, I'm wondering - if you can pressurize a person for deep sea diving then why can't you de-pressurize them for mars walking?

Nope. The pressures are extremely different. The pressure on Mars is about 10 millibars, or about 1 percent of the equivalent atmospheric pressure on Earth.

At this pressure, water immediately turns to vapor. So in effect, your blood would end up boiling. Anyeurisms and things as blood vessels in your brain explode.

Deep sea diving is different in that we're piling on a lot more pressure on our bodies. It's fairly easy for our bodies to cope with more pressure. Depending on how deep you dive, the equivalent atmospheric pressure would be about 15 times greater. I'm not sure how much our bodies could sustain (just doing some simple googling on this), but that is probably near the limit.

But based on the sole fact of low pressure and lowering the boiling point of water, I'd say no.

Re:Oxygen requirements = yes, Pressure = no.

[swillden]

Deep sea diving is different in that we're piling on a lot more pressure on our bodies. It's fairly easy for our bodies to cope with more pressure. Depending on how deep you dive, the equivalent atmospheric pressure would be about 15 times greater.

To amplify, because our bodies are made mostly of water and incompressible solids, increased pressure has very little direct effect on us. We have some internal air spaces that have to be equalized, but once that's done, increased pressure does little. In fact, the only way in which increased pressure does affect us is in that it alters the behavior of our body chemistry somewhat. At the pressures that divers go to (people have been to over 30 atmospheres, and we could probably take far more than that) the most significant change is the way in which gases dissolve and permeate our tissues.

Higher pressures causes more of a given gas to dissolve into our blood and tissues. For example, as high amounts of nitrogen dissolve into our tissues we experience a narcotic effect (called "nitrogen narcosis"). Oxygen is a highly volatile element and becomes toxic in large amounts. For this reason, very deep diving uses a lot of helium and very little oxygen or nitrogen. Lowering the percentage of oxygen in the breathing mixture keeps the amount of oxygen in the diver's body below toxic levels. Deep diving is done on oxygen mixtures that are so thin you'd asphyxiate if you breathed them on the surface.

And that leads directly to a major problem with trying to breathe on Mars. In the martian atmosphere, the pressure is so low that even if you were breathing 100% O2, you'd die of oxygen starvation.

To understand why, you have to understand a little about how mixed gases and dissolved gases behave under pressure. The key concept is called "partial pressure", and it's very simple. The partial pressure of a gas in a mixture is simply the ratio of that gas times the pressure of the whole gas. So, if you're breathing 20% O2 at sea level (one atmosphere), you're breathing O2 with a partial pressure of 0.2 atm. For convenience partial pressure of O2 is written "ppO2".

In direct correspondence to partial pressure, there's another concept called "partial tension". Tension is the measure of the "pressure" of gas dissolved in a solid or liquid. In your body, the amount of a non-inert gas, like O2, that participates in chemical reactions is directly proportional to the partial tension of that gas. In turn the partial tension of a gas in your body tissues is equal to the partial pressure of that same gas in the air you breathe (well, it's not always equal, it takes time to reach equilibrium, and some other factors mean that it's never *exactly* equal, but never mind all that). It's reasonable to just assume that, at equilibrium, ptO2 = ppO2.

So, in order to have enough O2 to function, your bodily tissues have to have a certain ptO2. Your tissues could equilibrate to the martian atmospheric pressure (assuming the boiling point of water doesn't become an issue), but you'd die because even at 100% O2 the ppO2 = 0.01 atm. IIRC, you need about five times that to function.

At the high end of pressure scales, your body can endure ppO2 of up to about 2 atm. Divers generally try to keep it below 1.6 atm, 1.4 atm is what the training agencies recommend. So, at 30 atm, breathing gas with only 1% O2 is perfectly adequate, even though you'd asphyxiate with so little oxygen at sea level. 1% O2 at 1 atm is a ppO2 of 0.01, just the same as 100% O2 at 0.01 atm, i.e. Mars.

Re:science

[OrthodonticJake]

I don't know; science fiction writers have been right about the future of technology many times. Of course, you could argue that it's because they imagine something and then scientists see their ideas and say "Lets do that", but I think there's at least one other factor involved. The more scientific of the scifi writers try to make their writing as explainable as possible, and it's that goal that makes their ideas easier to implement. So I think that having the science fiction crowd along for the ride is definitely a good idea.

Re:ET, is that you?

[Artifakt]

Of course the early Spanish and such knew that European diseases could be fatal to the "Indians". But, they didn't have a germ theory of disease or other modern explanations, and they didn't know about immunity mechanisms at all. They were genuinely surprised to see diseases that had a relatively small mortality rate in Europe, or that generally took months to kill, spread so fast among the indiginous peoples, and often kill within a day or two. This is confirmed by the many letters and messages they wrote relating how remarkable it was. Most of these were sent by Roman Catholic monks, who it appears often genuinely tried to help, but by gathering Native Americans into crowded conditions usually made things worse.
The Bio-warfare attacks with smallpox laden blankets and such generally happened in the 1700's to 1750's, not the 1500's. Those people's ethics probably weren't any better than the Conquistadores, but they understood a bit more about the technical end of handleing Smallpox and other diseases. One of the most notable of these was Lord Amherst's decision to distribute blankets known to be full of smallpox, an attack which he justified in his letters and memoirs on Biblical grounds, although the second most well documented use of smallpox was at the order of a mercenary garrison commander near what is now Chicago ILL, who was a freethinker and justified it on the grounds of European racial superiority. While these two attacks are the only ones with extensive documentation made at the time by the chief perpetrators, it seems probably that there were more, ranging from a low estimate of about 10 to more than 100 depending on the historian's best guess.