I was wondering how a planet like Earth might lose its atmosphere. Could: a) a natural phenomenon, some kind of collision etc cause this, and if so what else would happen to the planet (ie extent of surface damge, changes in orbit, rotation etc) as a result of the collision or other natural phenomenon. b)Is there any conceivable thing humans on earth could do that would blow off our atmosphere? c)Is there any way a hostile party in space could do to divest the planet of atmosphere without physically destoying the surface itself?
quote:a) a natural phenomenon, some kind of collision etc cause this, and if so what else would happen to the planet (ie extent of surface damge, changes in orbit, rotation etc) as a result of the collision or other natural phenomenon.
Yes. Solar winds can and do strip atmosphere from the earth. It's a slow and gradual process, and the earth re-claims a lot of the lost atmosphere through its gravitational well.
Inter-planetary collisions powerful enough to strip atmosphere from the earth's gravity well would obliterate the entire surface of the planet.
Rotation does not affect gravity. Mass affects gravity. The earth spinning faster or slower does not influence its gravitational pull.
If the earth's magnetic field was dimenished significantly, solar winds would be more capable of stripping atmosphere as well.
quote:b)Is there any conceivable thing humans on earth could do that would blow off our atmosphere?
Nukes. And lots there-of. But again, lost atmosphere would likely be reclaimed over time.
quote:c)Is there any way a hostile party in space could do to divest the planet of atmosphere without physically destoying the surface itself?
This becomes an issue of mass. An exterterrestrial third party can sift atmosphere from the earth. But what becomes of that lost mass? If it's stored on the ship itself, then as the gravity well of the earth shrinks, the gravity well of the ship increases. See wikipedia:
quote:The atmosphere has a mass of about 5×10^18 kg, three quarters of which is within about 11 km (6.8 mi; 36,000 ft) of the surface.
As the gravity well of the ship increases, it's ability to remain in earth's orbit becomes threatened. It would require a greater relative speed to maintain its orbit.
As far as harvesting atmosphere from orbit, there's no current technology available for such an endeavor. In theory, a surface-to-orbit tether/elevator might work (one heck of a vacuum!!). But you're still lifting mass out of the earth's gravity well, even if it's just atmosphere. That's a lot of energy spent moving mass.
If the aliens aren't collecting the mass, and just intend on blasting it away from the earth, then simulating or stimulating stellar winds might be more effective.
[This message has been edited by Rhaythe (edited June 02, 2011).]
Earth's atmosphere is held in place by the Earth's gravity. One must also consider buoyancy forces of one gas to another. It's a quite complicated mechanism that I cannot explain with my current knowledge or writing space. However, creating a sufficient blast/energy wave could literally blow the atmosphere away. The other way is to introduce a large amount of non-breathable gas that would alter the atmosphere's composition in a way to make the conditions too hostile to support life.
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Addendum to my earlier post - the space "vacuum" would also be pointless on its own, as the earth's atmosphere is already surrounded by a vacuum (obviously). So the tether/elevator would require some other mechanism for stripping gasses. Posts: 487 | Registered: Mar 2008
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Actually, interestingly enough at the beginning earth's atmosphere was very similar to the way Venus's is now. Something along the lines of 400 times the atmospheric density, and similar concentrations of sulfuric acid and CO2.
I would greatly recommend reading into how the earth went from being unable to sustain water on the surface to the formation of the oceans, and how those oceans then served to filter the CO2 out of the atmosphere and greatly reduce atmospheric density, and then the continual change when life first appeared and greatly bumped the Oxygen levels in the atmosphere. Not only will it provide great ideas for stories and help you build a more believable world, but it's also really interesting.
[This message has been edited by Natej11 (edited June 02, 2011).]
Rhaythe, you had the right idea with your "heck of a vacuum," just not quite the right mechanism.
Open stable wormholes that have one end in the atmosphere near sea level and the other in deep space. Atmospheric pressure at sea level will force air into the wormholes because there's no countervailing pressure at the other end. With nothing to catch the air at the vacuum end, air will continue to flow out through the wormholes until the atmospheric pressure on Earth is close to zero. The rate at which that happens will depend on the size and number of the wormholes.
quote:Rotation does not affect gravity... If the earth's magnetic field was dimenished significantly, solar winds would be more capable of stripping atmosphere as well.
Now, there is the point that the moon's existance, (Earth's) rotation and tidal forces help drive the magnetic field via a dynamo effect. However eliminating the moon wouldn't eliminate the magnetic field, as tidal effects from the sun would suffice. It remains a mystery why Venus doesn't have a magnetic field, while Mercury does. Also, not that while Venus has had its free hydrogen stripped from the atmosphere, the remainder of the atmosphere is denser than Earths, so solar wind only has a limited effect on heavier gases.
Magnetic tornadoes (or flux transfer events) may help strip the planet. These act like windows in the atmosphere for the solar wind to get through. Once again, this would probably take a long time. I wonder if they can also funnel atmosphere out? Consider what would happen if an extremely persistent solar flare created some of these on Earth.
You need to steal an atomsphere? No problem! Takes a diabolical mind and it is clear my bright friends just aren't devious enough.
It will take an advance technology and an ambitious effort but the solution is simpler than creating a vaccuum sucking wormhole. Allyou have to do is replicate an experiment you can do in your kitchen.
Take a collander. Fill your sink with water. Set it onthe water and watch what happens. Look at that! It sank and the water filled the bowl through the mesh at the bottom! If you cover the mesh (papertowel will work but wax paper is better) you can extract the water in the bowl. Apply the same principle to steal your atmosphere.
It will take a 3-dimensional mesh sphere. Erect it outside Earth's atmosphere. You'll need to invent a material for the job (energy-force field grid will work). Contract the sphere on the planet. Get it as close to the surface as possible. Cover your grid (make your force field solid). Expand your sphere (100 miles over the surface). Dimple one side of your sphere (I suggest the dark side - solar wind likely would be pushing the atmosphere to that side anyway) so the gasous mass will fall toward the gravity well. Now open the other end and invert your sphere to capture the gas within. Look at all that nitrogen and oxygen you have for your Dyson sphere! Now take off with your sphere while all life on the planet asphyxiates. Of course, the water left on the planet will now boil, filling the planet with an oxygen rich atmosphere so plan on a second trip back to get all of that as well.
Actually, there is an easier way - one that won't require speculative physics such as wormholes. Send tonnes and tonnes of magnesium or aluminium (metal) powder into the atmosphere. The friction from reentry would make this sufficiently hot to react (it doesn't need much to burn). They both react strongly with oxygen, until the oxygen is burned up. And then they will start reacting with nitrogen. Once the nitrogen is gone (and all the water will be gone too, by that stage, both via a reaction with Mg3N2 precipitates falling into the seas and via boiling as snapper suggests) then there is not much atmosphere left - mainly 0.7% argon that doesn't react much with anything. (Note, all CO2 and H2O will react with the metals, therefore using up most of the lesser gasses in the atmosphere as well).
By the way, I know that the USA calls aluminium "aluminum", but do you call magnesium "magnesum"?
Now, for a title of a story that uses this method, perhaps Noble Trinity, with characters called Neon Light, Argon Naught and Krypton Night.
[This message has been edited by Brendan (edited June 02, 2011).]
This all sounds interesting but it's been done already... in fiction anyway. I read one short story many years ago where a ship full of aliens seriously considered using some type of gravity device to strip the atmosphere. In one book explorers came across a de-atmposhered planet and found evidence there was one at one time. They never figured out what stripped it away though.
Modifying Eric's idea . Have one huge wormhole to an alternate universe where the Earth doesn't have an atmosphere. Some experiment gone crazy-like John Ringo's "Through The Looking Glass"- or a natural event perhaps?
In one of the later Star Wars books the Yoozhan Vong (bad guys), use a biological weapon, essentially a very virulent single-celled organism that devoured all life in its spread, in the process producing oxygen in such quantities that eventually the entire planet went up in a gigantic conflagration.
Not exactly stripping the atmosphere away, but it certainly made it toxic and unlivable.