New Environments, getting offworld so humanity survives

According to an expert who gave a lecture on this topic it takes between 300 and 500 years to terraform mars, which is still a long time, (in people years).

Stephen Hawkings thinks the human race will be fine if it can survive the next 100 years. Problem is he isn't very optimistic about our ability to do that. 

As with much popular media, the bbc documentary is exagerating.

1. Teraforming mars isn't as simple as adding oxygen and water.

In reality, mars used to have a lot more oxygen. It lost it in the normal means that planets continuously lose their atmospheres. Gass moves at a very high velocity, at the molecular level. Whenever a molecule of gass reaches the escape velocity for that planet (the same speed a space ship has to achieve to leave an orbit), and doesn't run into another molecule on its way out, it leaves the planet and floats off into the vacuum of space.

Added oxygen won't stay very long due to its low mass. That is the biggest impediment to colonizing mars at the moment. While it is 50% farther from the sun than we are, that only results in  ~55% less solar heat.  The mass of mars, on the other hand, is right around 1/10th that of the earth, so gass only needs 1/10th the velocity to escape. With the way that gass velocities are distributed (a very steep bell curve), that makes a huge difference.

 Its present atmosphere is fairly stable because it is mostly carbon dioxide, which is substantially heavier than normal oxygen (though not as heavy as ozone). At one time in the distant past, it had an atmosphere much like that of earth, but as time goes on, more and more molecules escape until lowering pressures and temperatures (particularly when greenhouse gasses leave) create a near equilibrium and the gass loss slows to a nearly immeasurable rate. Where that near-equilibrium lies depends on the mass of the planet, and its thurmal characteristics (mostly distance from the sun). Mars just falls short of being able to keep a lot of oxygen.

 Trying to fight the ballance that has naturally been reached on mars won't be as trivial as simply making a lot of oxygen, no matter what the idealistic storytellers say. Terraforming mars is still like trying to inflate a baloon with holes in it. Yes, we can produce enough oxygen to get the atmosphere of mars into roughly the same proportions as that of the earth, but no, we can't keep it there.

Not to say that it can't be done. It will require either 1. A whole lot of sustained oxygen production. Much more than is currently produced by the entire planet earth, or some sort of method to keep the air there. That is, we can devote all our efforts into blowing a bunch of air into the perforated balloon, or we can also try to patch some of the holes.

As far as I am aware, the only way we can do that is to build air tight (or nearly air tight) structures around the growing plants. That is a far bigger obsticle than planting some algae and letting it grow.  Since we are usingliving organisms, the domes will also have to be somewhat translucent if we ever plan to use anything that requires much light. Also, more CO2 will have to be introduced  into the structures to keep the plants from asphyxiating.

Most pro-colonization propiganda likes to overlook or understate the speed at which the atmosphere returns to its ballancing point. They also like to exagerate the affect that adding some atmosphere to mars will have on the temperature. Temperature and size are oppositional forces in the dynamics of an atmosphere. While more atmosphere will increase the heat somewhat, increases in heat will have a much larger affect on the rate at which gasses escape.  Its easy to ignore that, using a partial equation or some creativly edited interviews makes it more believable.

2. It won't be that hot in a mere 50 millenia.

The people who are now saying that we have 50000 years until the earth is a scorched inferno are the same ones that spent the 90s Not reallytalking about how we would all be underwatter due to global warming by now. 1,000,000,000 years would be a better estemate. The sun is just about the last thing that we have to worry about as a species. Diseases, war, and commets are our biggest threats now.  

Globalization has made illness much more dangerous than ever before. We don't even know how many potentially extinction causing illnesses have occured in the past, but unless our medical technology improves greatly, the next one will probably the last. And we have had some close calls. Ebola, anyone.

Though I hate the media over-hype of modern plagues. Sars was a joke. Traditionally, every 15-50 years, a really nasty flue has come out of asia and ravaged the world. Sars was just the latest, and also probably the most mild in recorded history. We kind of have flue treatment down, now. Even without vaccination, our ability to quarantine and sanatize make slow moving, low fatality illnesses benign. And our ability to treat what used to be lethal symptoms makes flues laughable. Nobody should ever die of a flue anymore.  But I should stop before I go on my heroin rant.

Wars are an obvious threat, but only recently have we developed the ability to exterminate our entire race. Arguably, we don't have it yet.

Shit flying around in space is our other big danger. We have evidence of at least 3 impacts that could have wiped out human life entirely. The oldest of which is believed to have created the moon, but thats not something that can be verified. The other two might not be as dangerous as they seem, and may have even occured while human-like life was on the planet, but again, dating a crater isn't a very precise thing.

What is really dangerous about something hititng the plannet, is that we don't know the odds. We really know very little about what is out there, even in our own solar system. We don't know how many asteroids or commets are on intersect courses with earth, we can't even decide how many planets are in our little solar system. We do know, though, that every solid planet (or planet sized rock of some other type) that we have seen so far shows signs of some serious impacts. 

But not to be an alarmist, most of the craters, rings, planets, and tilted orbits are very old, and the number of rocks flying around has probably decreased significantly since then. I am really more worried about SARS. But again, we don't really know. We haven't been around long enough.

The earth is about 4 billion years old. The universe, depending on which expert you ask is between 7 and 14 billion years old. Recorded history is 50000 years, and the fossil record goes back 500,000,000 years (roughly the last 1/8th of the age of the earth). Most of what we know about the past is probably mostly wrong. We have no records of any living multi-cellular organisms more than about 500 million years old, but we also don't have many rocks more than 500 million years old that are big enough to contain the fossile of a multi-cellular organism. Earlier than that, we think that there probably weren't any complex forms of life here, but we don't have any substantial evidence. We could have just as easily had another dozzen or so epochs.

What we do have records of indicates that life comes and goes. Most of the more successfull life forms of the past probably drowned in their own wastes and/or starved themselves out.  Again, there are some really big holes in the records, and we don't have any accurate measurement of dates, so what we "know" could be way off. For example, carbon-13 dating relies on several assumptions about our atmosphere, the sun, and cosmic radiation. Sometimes numbers that are largely agreed upon change overnight. 

 Anyway, I guess i kind of went on a rant. I like bbc documentaries, I really do.  But Merlin is no Carl Sagan. And colonizing mars is definitely a step in the right direction. We should get started right away. Actually, we should have gotten started a long time ago. Traveling to mars isn't much harder than traveling to the moon, and the large amounts of CO2 would be very handy.