Does anyone know haw it would be posible to make a breathable atmosphere on Mars?  Same composition, but less density woudl be fine.  Something that people can survive on.
209834
Terraforming Mars is one of the big subjects in Astronomy today; everybody has a different opinion on it. To answer your question:\n\nFirst it is necessary to heat the planet. Perhaps the use of orbiting mirrors or the introduction of CFCs into the atmosphere would do the trick. As a result of warming past the melting point of carbon dioxide, or about -78 degrees Celsius, a large amount of this gas will be released into the atmosphere, increasing the atmospheric pressure to one that is somewhat survivable to humans with oxygen supplies. As the planet warms even further as a result of this greenhouse gas the melting point of water will be reached, and a large amount of liquid water will be released onto the surface, perhaps enough to cover about 40% the planet in ocean. Of course, some will evaporate, causing water vapor, another greenhouse gas, to further warm the planet. Plants and algae could be introduced to the now warm and wet planet, to metabolize the large amount of carbon dioxide in the atmosphere and turn it to oxygen. After all of this has occured, over anywhere from 50 to 10,000 years, Mars will be inhabitable and will resemble Earth greatly.\n\nFor more information, see this page: http://en.wikipedia.org/wiki/Terraforming
413222
Some planets are too hot for water, some are too cold. The larger planets are made from methane and other gases.
190502
It depends on a variety of things: the angle of entry into the atmosphere, the size of the comet, the composition of the comet, etc.\n\nAn interesting note: one of the proposals for terraforming Mars is to use ice-coments to raise the amount of water vapor, create a greenhouse effect, and both warm the planet and add to the water on Mars.
672210
If you were able to create an Earth-like atmosphere on a planet, then it would scatter sunlight just as Earth's does and the sky would be blue and bright when the sun was on it. If you just have a pressurized dome (a more technologically feasible situation), there wouldn't be enough air to significantly scatter light and you could look out of the dome and see black sky.
131551
dude above this comment addressed some of the problems . . . but what about the solutions?\n\nFor my astrobiology class I did research on terraforming Mars, and learned quite a bit.  The first thing that would need to be done is landing, constructing miniature chemical fixing plants that could do to the atmosphere exactly what we're doing to this planet right now: release greenhouse gases that otherwise would be locked in the regolith. This would have to be done first to allow the planet to warm up a little bit, but this would take a few hundred years. You see, this would project would have to have the full commitment of the entire human race over a few thousand years for this to be "completed."\n\nAfter a few hundred years of warming,  you might actually outgas enough atmosphere from the regolith to hold liquid water stably, you might have a little more CO2 to build atmos. pressure, but growing algae or anything would require genetic engineering, since algae, im sure, is not going to grow in soils containing peroxides and epsom salts. They would fix the atmosphere to contain more oxygen. This would also take a few hundred years as well.\n\nAssuming we had the patience for this, we could have some sort of atmosphere close to 60% the pressure of ours within 600 years, and the temperatures from the 50s-70s (one scientific paper said something about 77F being reached feasibly). So this terraforming is do-able, but do we need to? have we finished discovering things on Mars before we start erasing it with running water and weather systems? \n\nSome say there is still a lot of water on Mars, enough to make an ocean covering the entire planet about a few feet deep (thats a lot), but that would take a lot of work to achieve.  Also, you have to realize that all this work would not be permanent.  Mars has no magnetic field, and thus no real protection from the solar wind which would slowly strip the planet of its atmosphere. \n\nthe "mars project" would be fruitful but not permanent, and would work for probably a good several millenia, but would need maintenance. . .  \n\nim done typing
601218
It most likely will never melt, as Mars is far from the Sun. If it does, it might not last long, as it has no atmoshpere and a weak gravitational pull.
91484
Since the first guy did not even bother to read your question...\n\nYea, you've hit one of the big mysteries in Science - the early atmosphere. Lots of people are doing research in this area.  I just read a great book that talks about it: "Genesis: The Scientific Qest for the origins of life." Great book - check it out.
328540
It's completely beyond our current science and technology to replicate the environment of Mars with such precision that we could be confident that we'd have the exact same (or even similar) conditions for life as exist on Mars.\n\nIn addition, how would we replicate Mars' environment when we know so little about it?  You'd need to send thousands of probes to Mars to get enough information to even *begin* such an experiment ... and by the time you'd finish that, you could've already run a full set of experiments on Mars testing directly for the past or present existence of native life forms.\n\nA planet's biosphere is an incredibly complicated thing.  It's something that scientists seem to only now be learning about our own biosphere, unfortunately a bit too late.
176035
Living on Mars wont happen for a long time, \nFirstly we dont have the technology so we couldnt get there even if we wanted to\nSecondly it would cost a HUGE amount of money just to get the technology and then even more money to go into space\nThirdly, the journey to Mars is a couple of months at least so it would take a long time to get there and we dont know the effects of deep space radiation on the body yet so all the astronauts could die\nIn the near future ( say 50 years)  it is very unlikely the someone will go to Mars\nIn the far future ( say at least 100 years) then it is very likely\n\nAlthough if you mean someone living in an atmosphere on Mars rather than going there in a spaceship and landing and then coming back, well, it will take hundreds upon hundreds of years to do that as we have to create an atmosphere on Mars first and that is very very hard
382809
Carbon at room temperature and pressure is a solid, not a gas. If you raised its temperature enough to make it a gas, it would become highly reactive and would be too hot for you to breathe.
117671
There is no evidence to show conclusively that life ever existed on Mars, and the lack of evidence strongly suggests there never was life there.  If even bacteria lived there some trace would show up in the fossil record, and so far the probes have found no evidence of this.\n\nIt doesn't mean that there isn't life somewhere on the planet, or that life existed there once upon a time, but it's highly likely that there never all that much life on the planet.  Life tends to spread -- for example, no matter where we look on the Earth, we find some evidence of life, even if only bacteria, even in the frozen arctic or the middle of the sahara desert.\n\nAt the present time humans cannot live on Mars without an artificial environment.  The air pressure is far too low and the atmosphere has far too little oxygen.  The temperature extremes are far worse than even in the Antarctic.  \n\nWhile it is possible to build a "Marsbase" of some kind the difficulty lies in getting all that material over to Mars from Earth and then down from Mars orbit.  It's one thing to drop a probe through the atmosphere and bounce it hopefully somewhere within a 100-mile radius of its intended landing site; it's quite another to have a steady drop of material that all has to land in the same place.\n\nNaturally the builders could make use of local materials.  The main problem is the lack of water, which only seems to exist on the surface at the poles.  Therefore the base would probably have to be located at or near the polar areas of Mars, so that ice could be harvested and used to produce oxygen.
280096
How about a bowl of water beneath it? Is that within the rules? Alternatively one of the other posters is planning to drill a hole through the centre of the planet, you could always use their hole, it wouldn't break then!
272623
Check that first letter. I think it is "atmosphere."\n\nCheck this link:\n\nhttp://liftoff.msfc.nasa.gov/academy/space/atmosphere.html
187584
Well if I remember this right...NASA was doing experiments a few years ago with rhubarb and pumpkin plants. The C02 oxygen exchange was the greatest. Also there was something about a genetically engineered algae they were trying out
294246
Ah, lots of planets have water, it's a very common substance, however imn out solar system it's mostly ice. life as we know it needs floating water. Mars might have had this, but it looks like the climate on Mars took a wrong turn a few billion  years ago. THere might still be life there in the form on single cell organisms, but we need to be able to drill down the ground to find out. Europa is also a candidate for life asn it seems that it has floating water under it's cover of ice (2 - 3 km deep!). \n\nThere might be live in other solar system, but its very hard for us to see, so far we can only find huge planets around other stars, not planets like ours, but in a few years we should be able to see them and then we might be able to see if they contain oxugen and or methane, which can be an indication that life is present, however to be sure we must go there, which we unfortunatelly wont be able to do in a very long time
604977
The only way humans could survive would be underground and only if they had a reliable source of power such as geothermal or maybe nuclear if they had access to fuel.\n\nThe weather would make life on the surface unlivable.
270498
Although the gravity on Venus is very similar to Earth's (about 0.95 G), the other conditions of Venus' surface would not make for a very pleasant visit by an unprotected human.\n\nThe atmospheric pressure at 'sea' level on Venus is about 95 times that of Earth's atmosphere, which would be an equivalent pressure to being half a mile deep in the ocean.  The open pockets and cavities in our bodies would be completely crushed, and we would be unable to breathe.\n\nThat's assuming we'd want to breath.  Most of Venus' atmosphere is carbon dioxide, which is not exactly conducive to human respiration.  What isn't carbon dioxide is rather high in a number of sulfur compounds, including hydrogen sulfide (the stuff in sour gas wells that kills people very very dead very very quickly), and sulfuric acid (which is also not fun to breath, or even have on your skin).\n\nAssuming we had some kind of super-duper hard shell pressurized, armoured, acid-proof space suit with suitable oxygen supplies, we'd still have problems.\n\nThe average temperature on Venus is about 480 degrees Celcius (somewhere in the realm of 900 F), which is hot enough to melt lead, and the rivers of molten sulfur probably wouldn't be too hospitable either.\n\nThe only thing the planet might have going for it would be mineral resources, but we can probably get those just easily from the moon or even the asteroids.  That atmosphere is just too darned hostile.