Would Laythe really be habitable, Redux

[Holo]

[the most glorious post]

The forums won't let me give you any more reputation, but I love this post.

[peadar1987]

You're welcome

Fantastic work! I know that there is someone on this forum with the knowledge to calculate this So assuming Laythe gets as much radiation as Io, not Europa (which would be circa 36 Sv/day), the avarage dose on the sea level would be (more or less) 12.6 uSv/hr, right?

Closer to 12.1uSv/hr, as a conservative, all gamma-radiation figure, which corresponds to about 105 mSv/year, and a slight increase in the cancer risk. You're getting into some serious dose rates at even a few hundred metres above sea level now as well, better not be into hiking!

It is a bit of a fudgey calculation though, and it doesn't take into account the fact that if you're a colonist on Laythe, you're going to be working inside for most of the time anyway, giving yourself extra shielding. It also doesn't take into account radiation from other sources though, like rocks, food, and the air, which are all pretty significant on earth.

Basically though, if the atmosphere is toxic, you could probably go out and about your business wearing normal clothes and breathing apparatus, and not have to worry about giving yourself radiation poisoning, or even a very large increase in the risk of getting cancer, unless you're particularly high above sea level.

[peadar1987]

The forums won't let me give you any more reputation, but I love this post.

Aw, thanks!

[czokletmuss]

Closer to 12.1uSv/hr, as a conservative, all gamma-radiation figure, which corresponds to about 105 mSv/year, and a slight increase in the cancer risk. You're getting into some serious dose rates at even a few hundred metres above sea level now as well, better not be into hiking!

It is a bit of a fudgey calculation though, and it doesn't take into account the fact that if you're a colonist on Laythe, you're going to be working inside for most of the time anyway, giving yourself extra shielding. It also doesn't take into account radiation from other sources though, like rocks, food, and the air, which are all pretty significant on earth.

Basically though, if the atmosphere is toxic, you could probably go out and about your business wearing normal clothes and breathing apparatus, and not have to worry about giving yourself radiation poisoning, or even a very large increase in the risk of getting cancer, unless you're particularly high above sea level.

Thanks for the response! Well than, according to Kerbal Maps (http://www.kerbalmaps.com/) elevation map, there aren't that much safe places to stay on Laythe. Most of them are at circa 1000m above sea level, not including the polar capes.

And if your calculations don't include background radiation like this on Earth, I assume we should add 3mSv/year to the dosage (at least 3 mSv).

So apart from being completely dark (I hope inverse-square law will be implemented in the KSP so that there isn't the same brightness everywhere), probably very cold moon with (probably) toxic atmoshpere with traces of oxygen (not to mention its incredibily hard to get to 36Sv/day in orbit!) Laythe isn't that bad

[peadar1987]

Well, anywhere near the shores would be okay (especially if you were near a mountain, which would block out any of the radiation from its direction.

Also forgot to mention, my calculations assume a flux of 36 Sv/day perpendicular to the atmosphere. I don't know what the flux is like in the van Allen belts, but if it's directionally-biased, you're looking at having a far lower dose rate on the surface, especially when you're shielded by the planet from the worst of the radiation.

I'm guessing it'll be pretty dark, so agriculture will be very difficult, and it'll be on the chilly side, but I don't reckon frozen (this is just going on the characteristics from the game, they say it's not frozen, so the greenhouse effect must be enough to keep it from freezing!). And you're right, not dying of radiation poisoning on the surface is the easy part, it's getting through the lethal doses on the way there that's the problem, you're going to need a seriously heavily-shielded capsule!

(incidentally, the highest point on Laythe is about 5600m, the dose rate there with Io-levels of radiation would be a whopping 875 Sv/year! You would not be a healthy Kerbonaut if you went climbing!)

[czokletmuss]

(incidentally, the highest point on Laythe is about 5600m, the dose rate there with Io-levels of radiation would be a whopping 875 Sv/year! You would not be a healthy Kerbonaut if you went climbing!

That's nothing - in low Laythe orbit you would het 13.140 Sv/year! Thirteen thousands Siverts - no probes or stations for Laythe. Not longer than for a few hours, that is. I guess no electronics could survive 36 Sv/day (thats 1500mSv/hour!).

Well, anywhere near the shores would be okay (especially if you were near a mountain, which would block out any of the radiation from its direction.

Also forgot to mention, my calculations assume a flux of 36 Sv/day perpendicular to the atmosphere. I don't know what the flux is like in the van Allen belts, but if it's directionally-biased, you're looking at having a far lower dose rate on the surface, especially when you're shielded by the planet from the worst of the radiation.

From what I remember, Jupiter's mangetosphere rotates quicker than its moons move while orbiting. The result? Particles trapped in magnetoshpere hit mainly the trailing hemosphere of the moon, which means that the leading hemosphere should be much safer (the half of the moon is your radiation shield).

I'm guessing it'll be pretty dark, so agriculture will be very difficult, and it'll be on the chilly side, but I don't reckon frozen (this is just going on the characteristics from the game, they say it's not frozen, so the greenhouse effect must be enough to keep it from freezing!).

Assuming there is water in the ocean - what if there is ammonium hydroxide? It freezes in −57.5 °C (for 25% solvent). And I seriously doubt that there would be lots of oxygen - I guess it can be produced by radiation toring apart particles with oxygen atoms, but it would be very small quantities. NovaSilisko mentioned vulcanism added in the feature, so there would be lots of sulfur and other nasty vulcanic stuff - basically Io after collision with Europa with some Titan spraying on the top (ammonia, methane).

Edited November 14, 2013 by czokletmuss

[Holo]

That's nothing - in low Laythe orbit you would het 13.140 Sv/year! Thirteen thousands Siverts - no probes or stations for Laythe. Not longer than for a few hours, that is. I guess no electronics could survive 36 Sv/day (thats 1500mSv/hour!).

Time to invest in lead spacesuits!

[Brotoro]

Thanks for the response! Well than, according to Kerbal Maps (http://www.kerbalmaps.com/) elevation map, there aren't that much safe places to stay on Laythe. Most of them are at circa 1000m above sea level, not including the polar capes.

And if your calculations don't include background radiation like this on Earth, I assume we should add 3mSv/year to the dosage (at least 3 mSv).

So apart from being completely dark (I hope inverse-square law will be implemented in the KSP so that there isn't the same brightness everywhere), probably very cold moon with (probably) toxic atmoshpere with traces of oxygen (not to mention its incredibily hard to get to 36Sv/day in orbit!) Laythe isn't that bad

I don't think you are reading that map correctly. I've been to both polar caps on Laythe, and they are both very near sea level.

Also, Laythe clearly has more than a trace of oxygen, since our jet engines work as well there as they do on Kerbin, so Laythe probably has about the same partial pressure of oxygen as Kerbin.

PLUS, you keep assuming that diminutive Jool has the same strength radiation belts around it that Jupiter does, whereas I think it unlikely that such a small planet would generate such a field.

[czokletmuss]

I meant that we should consider polar caps as a hazardous place at all since they are at the sea level.

Maybe. Or it was just a cool feature (one more celestial body to use engines!) added for the sake of gamplay and it's going to change. Check what NovaSilisko said about Laythe (link on wikipedia) - it's going to change quite substantially.

But it's KSP universe, everything is more or less the same like IRL but scaled down - you have the same 1g on Kerbin and Earth but Kerbin is much smaller. I assume that magnetospheres are as strong as IRL but smaller too.

[Brotoro]

Also, regarding light levels on Laythe, I don't think things are as bad as you think. Laythe is 5 time further from Kerbol than Kerbin is, so it gets 1/25 the illumination. Assuming that the devs want Kerbin to have roughly Earth-like lighting conditions (32000 to 130000 lux at high noon), then Laythe would have 640 to 5200 lux at noon. This classroom I'm sitting in right now probably has a light level of around 400 lux (considerable more than your typical living room lighting of 50 lux). So you are not going to be stumbling around in the dark on Laythe.

[czokletmuss]

You are correct - but this pose some problems for vegetation. Plants with access to only 4% of solar energy on Kerbin will have... troubles growing. BTW, I really hope the inverse-square law will work for solar panels too.

[Brotoro]

I meant that we should consider polar caps as a hazardous place at all since they are at the sea level.

Good...I missed your 'not'. Regarding the direction that the particles bombard Laythe: I expect that the north/south movement of the particles (as the go back and forth between getting pinched at the Jool's magnetic poles) is much larger than the motion of Laythe through Jool's magnetosphere, so the particles would preferentially hit the poles of Laythe.

Maybe. Or it was just a cool feature (one more celestial body to use engines!) added for the sake of gamplay and it's going to change. Check what NovaSilisko said about Laythe (link on wikipedia) - it's going to change quite substantially.

Certainly the devs COULD make the game less fun by taking away the oxygen from Laythe and making it a radiation hell-hole, but they don't HAVE to do that. The KSP universe is indeed scaled down. And while this requires them to make the planets and moons have a mysteriously high density (at least for part of their interiors), it also gives the devs to opportunity to use a magnetic field strength for the tiny Jool that will allow kerbals to cavort with abandon there, and give the players more interesting places to visit.

[magnemoe]

Jupiter is larger than all other planets in the solar system combined including the other gas giants. It really is much larger than Saturn.

I know Jupiter is more massive than Saturn, also that Saturn is very light, however both are in the same class and not pocked gas giants like Uranus and Neptune

My point is that then discussing radiation and Jool we has no reason to think that Jool behaves just like Jupiter despite the name

Another issue we has an sample of two medium sized gas giants and two small as far as I know we don't know anything about the radiation and magnetic field around exoplanets.

[plainawesome]

It depends, if laythe has a strong magnetic field and atmosphere then it may survive and be habitable, though it's really close to jool, the tidal forces will rip the surface apart and it'll make volcanos

Hmm, never thought of that one. :I

[Holo]

Laythe would have more radiation and vulcanism than Io. This is because Laythe orbits at 271 relative Mm whilst Io orbits at 420.

[HafCoJoe]

It seems as though everyone is arguing that water on the surface would be frozen at 4 Celsius if it had a thick atmosphere or not or evaporated away if higher. NEWSFLASH: Water doesn't always freeze at bellow 0 Celsius! - Lakes and large bodies of water (I.E. Oceans and Laythe) have enough tidal heating and enough average temperature that the waters stay barely above freezing. Only if the entire surface is cooled enough does the water melt. I think that the surface would rapidly change temperature

I'm with all you guys with Photosynthesis in the deep oceans putting out enough oxygen.

Really though, In KSP Laythe has liquid water that is still on the planet, not frozen, and is 4 Celsius. How this is I have no clue other than for science!

P.S. Don't credit any of that ^

[Rokker]

In addition to Avera9eJoe's comment about tidal heating meaning water doesn't always freeze at 0 degrees C, let me give you a short history lesson on the magical non-SI temperature of Fahrenheit. One thing I have heard criticized about Fahrenheit is that freezing point is 32 instead of 0 and that Fahrenheit's 0 is, I believe, -17.777 etc.. The reason for this is that Fahrenheit when it was being formed was to be somewhere around the freezing point of brine at avg atmosphere, yes this is vague, I know, it doesn't mention the concentration of solution and whatnot, however, the point is that only pure water and certain solutions freeze at 0 degrees C and many solutions of water, specifically salt based, the freezing point can get drastically lowered. If you guys would simply read the wiki, it is even suggested that the lack of freezing implies that the seas of Laythe have a relatively high concentration of ionic compounds, likely salt. This combined with tidal forces, combind with volcanic activity, combined with a decent amount of heating from the radiation trapped in Jool's magnetosphere (depending on where you stand in the magnetosphere argument) say that the ocean could stand a chance of not being frozen.

[Crown]

Maybe Kerbals can live on Laythe like other people can on Darehitorimo. Just with a big jacket and an oxygen mask. Living in container-like homes to be protected from the sand storms. This sounds quite familiar now.

I think 800hPa is about the pressure on a 3000 meter mountain. So there shouldn't be a big problem regarding this.

Of course only if all this radiation isn't trying to cook the brave little green guys.

[Rokker]

Ok seriously guys, can we please just agree that IF radiation was high then they would fall back on the plans for colonization of Mars and the Moon and cover themselves in pre-existing top layer minerals until the radiation is shielded. and instead explore the habitability of Laythe as a place with a lower oxygen concentration than Kerbin, low temperatures and no apparent access to drinking water.

[Brotoro]

?..combined with a decent amount of heating from the radiation trapped in Jool's magnetosphere...

You aren't going to get any significant heating from radiation belts -- the particle density is way too low. Because the individual particles in a radiation belt have VERY high energy, they can damage important molecules in your body or your transistors... but there aren't enough of them to keep you warm.

[Brotoro]

Ok seriously guys, can we please just agree that IF radiation was high then they would fall back on the plans for colonization of Mars and the Moon and cover themselves in pre-existing top layer minerals until the radiation is shielded. and instead explore the habitability of Laythe as a place with a lower oxygen concentration than Kerbin, low temperatures and no apparent access to drinking water.

I'm not sure where Mars and the Moon come into this.

But because my jet engines work just as well on Laythe as they do on Kerbin (at equivalent atmospheric pressures), I would expect Laythe to have about the same percentage of oxygen in its atmosphere as Kerbin.

If Laythe's oceans are just salt water, drinking water would not be a problem, since distillation is very easy. If Laythe's oceans are a mix of water and ammonia, the separation is more difficult, but still possible.

[LLlAMnYP]

You still dont get that the surface and core would have to be impossible hot to heat up the atmosphere to anything close to where ice melts into liquid water.

When it comes to atmosphere warming it matters alot.

When you have heat from sun it will heat up the atmosphere while the radiation/lightrays travels through the atmosphere with very little actually reaching the surface which is why the surface temperature on earth is comfortable instead of blistering 200c like our own moon.

If you get same amount of energy from the interior that same energy is used to heat up the surface and water instead of the atmosphere, which means it would be boiling off long before any significant heat is added to the atmosphere.

Even if the water was literally boiling from interior heat there would still would not be anywhere near the effect of the atmosphere heating our planet for example experiences.

Besides we are talking about a moon here with 85% the pressure of our planet. Atmospheric pressure has alot more to say than the percentage of greenhouse gases when it comes to being able to hold heat. But either way there is no way it could be heated up anywhere near enough to allow for liquid water at such a distance from the sun.

Our moon heats up to 200c (and cools down to -170c) because it rotates so damn slow (thus being exposed to light and dark for extended times). And because there is no atmosphere to redistribute the heat evenly across the moon. However, the bulk of the sunlight actually goes towards heating the ground on earth as well. It is then convection, not radiation, that transfers the heat from the ground to the air above it. That is also a reason, why it is much colder in the mountains at high altitudes, that would not be the case had the sun heated the atmosphere directly.

For the same reasons, if the air temperature is as warm as 4c on Laythe, it is reasonable to expect, that the top layers of its surface are also close to that value, no more, no less.

[Rokker]

I'm not sure where Mars and the Moon come into this.

But because my jet engines work just as well on Laythe as they do on Kerbin (at equivalent atmospheric pressures), I would expect Laythe to have about the same percentage of oxygen in its atmosphere as Kerbin.

If Laythe's oceans are just salt water, drinking water would not be a problem, since distillation is very easy. If Laythe's oceans are a mix of water and ammonia, the separation is more difficult, but still possible.

I mentioned the Moon and Mars because, lacking a magnetosphere and therefore subject to higher radiation, the most common and feasible plans for radiation protection of long term bases there is to either pile dust on top of it (or make some kind of concrete analogue out of the dust) until the radiation levels are safe.

Your assumption of "a jet engine works equally well so oxygen must be the same" only applies if the engine is 100% efficient and burns all the oxygen entering often jet engines don't burn all of their oxygen meaning that as long as the ratio of oxygen entering the turbojet is above the amount being burned. However, Air intake efficiency is lower I think, implying more of Laythe's atmosphere has to be sucked in to maintain the levels of oxygen at the amount they burn. This would keep the engine's ISP the same whilst still being less efficient due to less oxygen.

Distillation of water can be easy, but it would all depend on how large the landing party is and how much water needs to be produced, the larger the amount of people, the more complex it can get to produce enough for them to have enough to drink and maintain an active lifestyle.

[LLlAMnYP]

Your assumption of "a jet engine works equally well so oxygen must be the same" only applies if the engine is 100% efficient and burns all the oxygen entering often jet engines don't burn all of their oxygen meaning that as long as the ratio of oxygen entering the turbojet is above the amount being burned. However, Air intake efficiency is lower I think, implying more of Laythe's atmosphere has to be sucked in to maintain the levels of oxygen at the amount they burn. This would keep the engine's ISP the same whilst still being less efficient due to less oxygen.

Well he didn't say that really. If for the same atmospheric pressure the function of an air-breathing engine is more or less the same, it's reasonable to assume, that the partial pressure of oxygen is also the same. Given, that the rest of the atmosphere is more or less inert and can be considered buffer gas (as is the case, say, on earth and perhaps, by extension, on Kerbin) a different concentration of oxygen will lead do a different behavior of the engine. So if the engine functions as normal, we should expect a similar oxygen concentration.

Admittedly, that may not be too valid if, for instance, Laythe's is composed of heavier or lighter gases, thus having a different speed of sound which, undoubtedly, would be important for an air-breathing engine.

[little square dot]

I really had no idea gas giants emit radiation. This is interesting. I am running to wiki

Almost everything emits radiation. You emit radiation.