life on an atmosphere-less planet

[gib65]

If there was a planet with bodies of water, but there was no atmosphere, could life still survive? Assume the sun that planet orbits is at the right distance.

 

I also realize that a planet with water would also have a thin atmosphere of water vapor, but this is still less than what Earth has. Earth also has oxygen, nitrogen, and an ozone layer protecting life from harmful rays.

[DrCloud]

Assume the sun that planet orbits is at the right distance.

 

Right distance for what?

 

With no atmosphere, Earth's average surface temperature would be down around 0F, meaning most of whatever water you're stipulating would be frozen.

 

Of course, if your planet were closer to its sun, perhaps there could be a pure water atmosphere (at a pressure equivalent to whatever vapor pressure the temperature of the liquid water would allow).

 

Although the stratospheric ozone keeps us air-breathers out of harm's way as far as UV radiation is concerned, so would a pretty thin layer of liquid water, so this isn't an issue for your planet. With no atmosphere, there wouldn't be any significant amount of dissolved oxygen in the "ocean", but anerobic life exists on Earth.

 

Asking whether life would survive implies something about pre-existing life -- as in, would any of Earth's current life forms survive under those conditions? That's not the same as asking whether life in some form could develop under these conditions.

 

Finally, remember the curious life-forms that have been discovered in the deep ocean around the hot vents on the mid-Atlantic ridge. It's doubtful that they "need" the atmosphere in any real way. On the other hand, the processes that they do need could well create an atmosphere over time.

 

So the question seems more complex than it might appear. HPH

[Sisyphus]

I guess the question would be, why not? Even if liquid water is necessary for life (which I doubt), you can still have liquid water without an atmosphere if you have some source of heat within the planet itself, like radiation or tidal friction.

[Edtharan]

The oceans of earth are usually simulated as a dense atmospheric layer.

 

The moon Europa had not atmosphere, but seems to be made of water (with a rocky core). This moon is one place where there might be a chance for life.

 

So, Yes. Life might be able to exist on a planet with no atmosphere and ther might even be one here in our solar system. We just have to go and check (and that is something else altogether).

[reor]

Gee, i once had a weird dream about a rocky moonlike planet (or moon?) with little (or no?) atmosphere, water under the surface and some dinosaur-like creatures...

 

I'm wondering if life could evelop in our current atmosphere. I've read it must have been different in the "early days".

[insane_alien]

the amount of radiation(X-rays and all that) at the surface would be substantially higher than here on earth especially if it didn't have a magnetic field. i would imagine that the life would be subterranean if it existed at all.

[herpguy]

With no atmosphere' date=' Earth's average surface temperature would be down around 0F,[/quote']

Are you sure about this? The bodies of water should absorb a lot of the heat. Also, seeing how water vapor is one of the largest greenhouse gases, that should also absorb some heat. I highly doubt the temperature of the planet would be as low as 0 degrees F.

[DrCloud]

^ Yep.

 

This is one of the easiest calculations to do, and it's usually introduced early in a physical geography class to illustrate how Earth's atmosphere, via its greenhouse effect, makes the planet habitable.

 

Using the power of the Sun (at our distance from it), the observed planetary albedo, and the blackbody radiation principle, the surface temperature with no atmosphere comes out at about 255C. Now, this includes no water vapor (a potent greenhouse gas) in any kind of "atmosphere"; however, it also uses the observed albedo, which is somewhat lower than it would be at this low temperature. These two omissions tend to cancel each other, and the albedo effect would dominate so that the actual temperature would be even colder.

 

Oceanic heat absorption has nothing to do with it, as this is a steady-state calculation, and water's heat capacity comes into play only when you're concerned about rates of heat storage or about moving heat around.

 

I posed this in the hope that the OP would clarify his question. Life without a significant atmosphere is one of those questions that exobiologists love to speculate over, but you need to specify the boundary conditions carefully. HPH

[gib65]

I posed this in the hope that the OP would clarify his question. Life without a significant atmosphere is one of those questions that exobiologists love to speculate over' date=' but you need to specify the boundary conditions carefully. HPH[/quote']

 

I didn't know it depended on so much - thanks for educating me.

 

I re-read your first post, Dr. Cloud, and there seemed to be two questions I should address:

 

Right distance for what?

 

I'm just assuming that if the sun was too close, all life would burn up (i.e. couldn't even be initiated) and if it was too far away, it would be too cold. I didn't have a numerical distance in mind, just whatever distance makes for the "right" temperatures for life to thrive.

 

Asking whether life would survive implies something about pre-existing life -- as in, would any of Earth's current life forms survive under those conditions? That's not the same as asking whether life in some form could develop under these conditions.

 

I was thinking about life starting on such a planet and having the opportunity to evolve. But taking Earth's specimens and transplanting them on another planet is also an interesting question. I doubt that all the life forms you described evolving around hot vents on the ocean floor really depended a lot on the fact that Earth has the specific atmosphere it does... or do they?

 

In any case, I think my question was answer, so thanks everyone.

[Edtharan]

This is one of the easiest calculations to do, and it's usually introduced early in a physical geography class to illustrate how Earth's atmosphere, via its greenhouse effect, makes the planet habitable.

Well Europa, out near Jupiter, is a lot colder than here on Earth. Yet it is strongly believed that it has liquid water on it. Due to the massive tidal forces of Jupiter, the rocky core gets squeezed and heats up. This heating would be enough to melt the ice into water. Evidence for a body of water on Europa is that one of the spcecraft sent there measured a magnetic field. This could only have occures if ther was a layer of electrically conductive liquid there. On Earth we have a layer, in the core, of liquid Iron that generates the Earth's magnetic field. On Europa, this might be done with a salty layer of water.

 

So on Europa, we have good evidence that ther is liquid water, in a place in the solar system that would noramlly only have ice, as it is far below the freezing point of water.

 

If locations like this can exist on a moon orbiting around a large planet and scientists have discovered many large planets around other stars (large planets are easy as they can cause the parent star to wobble and this can be detected), then it is very possable that life on Plantest is rare, but life on Moons, might be more common (as there would be more moons in places places that could lead to liquid water).

[SmallIsPower]

Life exists in extreme environments

microbial species thrive in environments with broad extremes of temperature, ranging from deep-sea,hydrothermal vents (about 114°C [237°F]) to Siberian permafrost (−15°C [5°F]). (Above about 130°C [266°F], complex organic molecules become unstable and begin to break down. This temperature may comprise an absolute upper limit for life based on the limitations of carbon chemistry.) In addition, microorganisms occupy nearly the entire pH range from about 1.4 (extremely acid) to about 13.5 (extremely alkaline). Microbial life also occupies an equally broad salinity range from freshwater to saturated brines (containing about 300 percent dissolved solids) where salt (NaCl) precipitates. Finally, organisms also survive at very low water availability by creating desiccation-resistant structures that can survive for prolonged inclement periods.