Slashdot Mirror
NASA Prototype: Could It Make Mars Breathable?
spiralx writes: "Scientists at NASA have successfully tested a solar-powered machine that takes carbon dioxide from the Martian atmosphere and produces pure oxygen. It will be tested for real on the next lander to go to Mars, planned for 2003. The article is here at Line One News." Mars will start seeming a little closer as news like this continues.
I think there is a big question here. While I do see the merits of this on a small scale (ie. for a habitat of astronauts on a mission, etc.), there are serious questions about possibly doing this on a large scale.
Eventually, people are going to want to do this to the entire atmosphere of Mars to make it breathable. What will happen then? Should an undertaking like that be considered? Should we totally alter a foreign planet and bring it away from its natural state? What would the result be?
While today this may seem like science fiction (Aliens, Total Recall, etc.), it won't be all that long before this kind of thing becomes a real possibility.
It is a curious but worrysome proposition.
Using your sig line to advertise for friends is lame.
The Evolution of Earth's Atmosphere
- Earth's early atmosphere might have originated from the capture of gases in the solar nebula before dissipation of the latter by the Sun
- the above theory is no longer the accepted one
- rather, we feel that the Earth's early atmosphere was formed from the vapourization of incident comets
- in the accretive atmospheric theory, the early atmosphere would have been rich in hydrogen - H and H2
- in the cometary atmosphere theory, the atmosphere would have been poor in hydrogen
- in either case, the atmosphere would have had water vapour (H2O), methane (CH4), ammonia (NH3), carbon dioxide (CO2) and carbon monoxide (CO)
- these molecules are still found in the gas giants
- the evolution of the atmosphere is a result of these processes:
- gravitational retention
- volcanic outgassing
- solar ultraviolet radiation
- processing by early life
Gravitational retention- molecules in the atmosphere move about using thermal energy
- energy of motion is called kinetic energy
- we define temperature as being the average kinetic energy of the particles (atoms, molecules) of a substance
- the kinetic energy of a molecule with mass "m" and velocity "v" is a familiar result:
- K.E. = 1/2 mv2
- the average amount of thermal energy for a molecule in a gas is:
- K.E. = 3/2 kBT
- here kB is Boltzmann's constant
- these two expressions represent the same quantity, hence:
- 1/2 mv2 = 3/2 kBT
- solve for v: v=(3 kBT/m)1/2 (1)
- equation (1) tells us the average speed of a given particle with a given mass and given temperature
- hotter particles move more quickly
- lighter particles move more quickly
- example: oxygen gas (O2) at room temperature
- mass= 5.3 10-26 kg
- T = 295 kelvin (= 22 celcius)
- kB = 1.38 10-23 J/K
- implies velocity v = 4800 metres per second
- pretty fast!!!
- molecular speeds in the atmosphere can be compared with the escape velocity for the Earth
- the escape velocity is the velocity required by an object to permanently leave a planet and escape into space
- it is
- vescape = (2GM/R)1/2
- M = mass of the planet
- R = radius of the planet
- G = gravitational constant
Planet --- Escape velocityMercury --- 4,300 m/s
Venus --- 10,300 m/s
Earth --- 11,200 m/s
Mars --- 5,000 m/s
Jupiter --- 59,500 m/s
Saturn --- 35,500 m/s
Earth's Moon --- 2,400 m/s
- to a first approximation, if the speed of an atmospheric molecule exceeds the planet's escape velocity, then that gas will not be retained in the atmosphere
- i.e., escape if vparticle > vescape
- in practice, this equation gives a false result, because for a given temperature gas particles have a range of speeds, from very fast to very slow
- the distribution of particle speeds is given by the Boltzmann distribution
- to retain a given gas in an atmosphere, a planet must have
- vescape > 10 vparticle
- therefore, the Earth lost all of its hydrogen and helium gases early in its history, but kept the heavier gases
Outgassing from volcanic activity- the interior of the Earth is heated by the decay of radioactive elements
- 4.5 billion years ago the surface of the Earth was a few thousand degrees kelvin and was more liquid than solid
- volcanic activity released gases such as water vapour, carbon dioxide, sulfur dioxide (SO2), nitrogen (N2), plus more methane and ammonia
- also released were gases from radioactive decay - argon and helium
- once the Earth had cooled down, heavy rains filled the oceans to their present depth
- water quickly dissolved the atmospheric CO2, where it forms bicarbonate (HCO3-)
- bicarbonate can form solids with calcium, notably limestone and chalk
- the atmosphere went from 80% carbon dioxide 4.5 billion years ago to 10% carbon dioxide 3.5 billion years ago (% by mass)
- at this time, H-C compounds (CH4) formed 80% and nitrogen formed 10%
Solar UV radiation- there was no oxygen (O2) or ozone (O3), so UV light easily penetrated the atmosphere and broke up CH4, NH3 and H2O into their constituent atoms
- hydrogen escapes, and oxygen combines with methane to produce carbon dioxide and water
- nitrogen became the dominant gas roughly 2.5 billion years ago
- in the absence of hydrogen, oxygen and ozone could exist in trace amounts thereby stopping most of the UV light from penetrating deeply into the atmosphere
Processing by early lifeYou can't handle the truth.
This device is not on the scale to change a planetary atmosphere. This is mainly something designed for either exploration missions or bases.
Some sort of genetically engineered plant or algae would be more realistic for planetary alterations, although mass water supplies would be likely required for this type of operation. If machinery was used, it would most likely have to be constructed from local materials and have a vastly larger scale power source than sunlight (which is weaker there.)
And in other news, a young second-grader in Arkansas has learned that trees are able to produce oxygen from taking in carbon dioxide as well! A ground-breaking coincidence? The jury is still out for all of the facts :)
Mike Roberto (roberto@soul.apk.net) -GAIM: MicroBerto
Berto
You don't want to breathe pure oxygen though. One good spark and your whole habitat is gone. Producing the necessary gases to mix with Oxygen (i.e. Nitrogen, some other noble gases) will be much more difficult than the production of oxygen. It may be possible to get nitrogen by mining the regolith (loose sandy topsoil on Mars).
This strikes me more as a way of producing fuel and water than as a production of breathable air, which could be better done by plants, which would also serve as food source.
One more thing... what use can be made of the carbon byproduct?
---- El diablo esta en mis pantalones! Mire, mire!
Before we get a lot of half-thought out replies, everybody should go out and read the series of books Red Mars, Green Mars, and Blue Mars by Kim Stanley Robinson. The series deals, as accurately as possible, with the colonization and terraforming of Mars. Mr. Robinson is a stickler for detail; in fact, it gets a little boring at times (I never thought I would read so much about the geology of Mars). On the other hand, he's a stickler for scientific detail, and addresses some key points, such as:
"Can we develop a reasonable atmosphere?" It's tricky--Mars's crust and elemental makeup is different, it has a low gravity, and has greater elevation variation than Earth. A good atmosphere at sea level may mean the majority of the world has an atmosphere similar to the top of Everest.
We've done some nasty stuff to Earth. Is it right to ruin the natural state of ANOTHER planet, too?
Water. Is there water on mars, anyway, and if there's not, what can we do?
Surviving in low gravity.
Lots more. In any case, I'm sure many questions will be raised by people commenting on this story. I'm just as sure that the majority of them are at least mentioned in the RGB Mars books. Go do yourself a favor if you're interested in this story, and check these books out.
Long ago, before humans roamed the earth, and certainly before they had big telescopes and long-range rocket-powered probes, mars had a breathable atmosphere. Unfortunately, it all got baked away. The critical issue for a planet holding an atmosphere is whether or not it has strong enough gravity to hold particles moving at the speed that gas particles travel in their kinetic vibrations. Earth, for example, cannot hold hydrogen or helium gases. If you pop a helium balloon, the helium will eventually drift out of the atmosphere and into outer space.
Fortunately, since O2 molecules are much more massive than He atoms or H2 molecules, the earth can also hold an O2 atmosphere. Mars is also massive enough for this, but there's a problem. Mars is not massive enough to hold oxygen atoms or ions. This is critical because of the UV radiation that the sun emits, which breaks up O2 molecules. On earth, those oxygen ions come together with O2 to form O3 (ozone) which also helps shield the rest of the atmosphere from UV radiation.
Since Mars isn't massive enough to hold oxygen ions, it can't hold them up in the part of the atmosphere where an ozone layer would likely form. Thus, its atmosphere cannot be protected from more radiation, which further ionizes the O2 molecules. This is precisely what happened to the atmosphere on mars, as well as the surface water, and it is what will eventually happen to Mars's polar ice caps. I don't know exactly what the time scale would be for creating a breathable atmosphere, and I don't know how long it would take for it to dissipate, but I think you'd have to be continually working to keep it there, assuming you had the resources to get a planet-wide breathable atmosphere in the first place.
WARNING: there is a trojan on your
They're infringing on my patent. I have a working example in my back yard of a much more efficient machine, it is also solar powered, using multiple redundant flexible green solar panels to absorb solar energy, a self-maintainence system that will repair our adapt to compensate for medium scale damage, a robust, flexible physical structure capable of withstanding considerable force by dissipating the energy throughout the structure and bending, and utilises as fuel a small set of chemicals and H20.
It has further advantages over the solar machine exhibited, its components are easily recycled into a number of useful objects, various parts are edible and it aids in topsoil stability. It is also capable of self-reproduction given a requisite amount of available fuel.
It also comes in numerous makes and models suitable for every task, from extremely large to the inconspicuously small.
I call it The Plant, and I would demand royalties on this inferior implementation except that..well..its obviously so inferior no-one would ever buy it.
You can't win a fight.
I remember when I was kid playing the old game SimEarth on my Mac (not the Mac SE or the Mac Classic, but the Mac .. The Mac). Despite the game being very primitive and only in black and white, they had a couple of scenarios that were really interesting. One was to take Mars and make it livable and the other was to take Venus and make it livable. The easiest way to do both was to put in these devices that converted the carbon dioxide to oxygen (the hard way was to crash ice comets into the planet, both cooling it off and releasing oxygen .. don't ask me).
.. these sorts of transformations don't happen overnight).
I wouldn't say it's so worrisome. Making other planets livable for humans is going to become a fact of life if we ever decide to permanently leave this world. Mars is another system, but it's a dead system, and adapting it for human needs is not going to make species extinct or ruin our understanding of Martian phenomena (and even if it were alive, we'd have plenty of time to find out
But that's beyond the logistical nightmares of actually getting such a thing to work. Look at how long its taken our planet to register the effects of 150 years of industrial revolution, and the environmental change is a blip, an abnormality barely noticeable on the geological scale that scientists are still debating whether or not we are the cause. You can rest assured that by the time human beings are ready to purposefully alter the state of another planet's environment, they'll have the necessary expertise (and computer/robotics/cybernetic systems) to do it much more exactingly than you or I can imagine.
By the way, in the SimEarth game, the irony of it all is that once you terraform the planet (Mars was easier, Venus was much more difficult), sentient life can rise, become industrialized, and then ruin your environmental masterpiece. Maybe that should be the bigger fear, not what havoc we wreck when we purposefully change the environment, but what terrors we cause when we neglect it.
That way ...
*ducks back into the trenches having stirred up a hornets nest of stereotypes* :)
The universe being as large as it is, if life exists on Mars, our closest neighbour, life almost certainly exists on billions of planets. (This is of course accepting the fact that recent astronomical discoveries tell us planets are by no means rare. That gas giants are common suggests rocky worlds/moons are common as well. The reason I qualify certainly with almost is because within one solar system, the planets may be able to contaminate each other - remember that Mars meteorite found in Antarctica with bacteria inside.)
I personally believe life is ubiquitous. Intelligent life is another question. It I believe to be common, but nowhere near as much so as life itself. Regardless of the frequency of intelligent life, if life in any form exists on Mars, that life isn't important as it is not the least bit unique. We see nothing on Mars but the possibility for single and possibly multicellular microscopic life. This viewpoint seems to be where we disagree. If there were complex life forms on the planet, I would agree with you in that we should leave it alone. However, there are not.
If extraterrestrial life is everywhere, it doesn't strike me as that great of a loss to perhaps exterminate or at the very least dramatically change the habitat of one planet's native bacteria. Is it that great a price to pay in order to forever alter the current situation of the human species? Right now, we have all our eggs in one basket. One catastrophe of great enough proportions, whether it be accidental or deliberate, could wipe out our entire species. I would like to alleviate that risk in as short a time as possible, whatever the cost.
Once that is done, we can pick and choose as much as the more cautious people desire. Until then though, all it takes is one mistake, one fluke chance, one random event, and we're no longer a living species. We didn't survive this long as a species by taking chances that great.
(To argue that humanity's extinction would be good is just plain silly. We're just as natural and only a couple steps up from monkeys and gorillas. If you believe that human beings are a plague on the universe, help fix the problem and kill yourself. After all... the people with the time and money to spend considering such a thing are almost always among the world's biggest consumers/polluters. When you're starving to death, you have a few more pressing concerns. Note that I don't claim to have ever been in that situation, since some like to jump on things like that.)
------
If a tree falls on an anonymous coward yelling 'first post' in the forest, does anybody hear?