Speculation of the composition of Eve's atmosphere

[AstronautGeologist]

Why is Eve's atmosphere purple?

"The atmosphere is possibly composed of iodine, given its purple coloration. " -KSP wiki page for Eve

The Evian atmosphere is likely composed of iodine. Iodine is a black solid element under standard conditions. Iodine goes from a solid straight to a purple gas, with no liquid stage that can easily be detected. Iodine, in the solar system is rare, and in Earth's crust its abundance ranks about 53rd at 0.450ppm to 0.500ppm.

Origin of Iodine on Eve:

Iodine has an atomic number of 53 placing it on the periodic table above Iron, Cobalt, and Nickel. Therefore its only produced in a supernova explosion. Large concentrations of iodine might be possible naturally in a region of the galaxy where supernova explosions happen frequently or from the remnants of a supernova of an exceptionally large star.

The heavier elements differentiate towards the core of a planet hence most of the iodine would be in the core, just as most of the iron, nickel, gold, uranium, thorium, etc. Perhaps Eve got torn up by something leaving only the core. Of course, it wouldn't just be iodine, it would also be iron, nickel, gold, uranium, thorium etc. Iodine is also produced by neutron bombardment of Xenon which in itself is a byproduct of Uranium decay so perhaps it's the leftover of a giant nuclear reactor, note a planetary core and mantle is a giant thorium/uranium fission reactor. There's also neutrons from cosmic ray spallation where cosmic rays hit something sending neutrons flying. It would take tens of billions of years for the thorium and uranium of a leftover planetary core to decay into xenon and get bombarded into iodine so such a planet could not be part of a star's planetary system, stars don't live that long, it would have to be the leftover core of a rogue planet, perhaps the leftover core of a brown dwarf star. Short of a passing neutron star or black hole, I can't imagine what could strip the rest of such a planet away.

A planet with an iodine atmosphere would have to have a very hot surface for pure iodine as a gas as iodine is a solid at standard temperature and pressure. Eve seems to meet the temperature criteria, since its surface temperature ranges from 40 to 150 degrees Celsius. The melting point of Iodine is 113.5 degrees Celsius.

Iodine, being one of the halogens, is a fairly reactive substance. The issue is that absent any processes to maintain the environment out of equilibrium, everything that can react with iodine will have reacted with iodine. Life will maintain the environment in such a non-equilibrium state, but the prospects for lifemay be poor. Geological processes could also do it, by bringing up substances that the iodine will react with. As for specific reactions, it reacts violently with some metals including aluminium, but of course those metals are unlikely to occur naturally in their pure state. a possible reaction then might be that of hydroiodic acid and carbonate rocks. Carbonate rocks on Earth are mostly biological in origin, but some are igneous so could occur on Eve (does Eve has volcanoes?). Hydroiodic acid is made by dissolving hydrogen iodide in water. Hydrogen iodide can be made by reacting elemental iodine with hydrogen or hydrogen sulfide gas, either of which can come out of volcanoes. The iodine-hydrogen reaction is accelerated by exposure to yellow light, giving an interesting means to control the reaction.

Looks like Eveian atmosphere to meh.

Edited June 13, 2013 by AstronautGeologist

[AstronautGeologist]

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Edited June 12, 2013 by AstronautGeologist

[Brotoro]

I think an atmosphere that thick made of iodine gas would be a lot more opaque that it appears.

I'm going with purple particulates, just because it's fun to say. And I'd like to check the upper atmosphere of Eve to see if if might support airborne organisms that are excreting the purple organic particulates.

[AstronautGeologist]

Brotoro, I'm crossing my fingers for clouds in a future update

[jwenting]

That close to the sun, iodine would certainly all be gas. Of course it doesn't take much iodine to give a volume of gas a purple tint so in theory it could be.

BUT you'd have to consider outgassing. At the temperature of the Eveian atmosphere, any light elements would quickly dissipate out into space (similar to what hydrogen gas does on earth, there's a constant flow of the stuff leaving the atmosphere, small but detectable).

So you want an atmosphere of stuff that's heavy, and gaseous at the temperatures encountered at Eve, probably near the triple point even so it can exist in solid and liquid for as well.

[AstronautGeologist]

Iodine vaporizes into a lovely purple gas which also happens to be quite toxic!

[AstronautGeologist]

Basic Information

Name: Iodine

Symbol: I

Atomic Number: 53

Atomic Mass: 126.90447 amu

Melting Point: 113.5 °C (386.65 K, 236.3 °F)

Boiling Point: 184.0 °C (457.15 K, 363.2 °F)

Number of Protons/Electrons: 53

Number of Neutrons: 74

Classification: Halogen

Crystal Structure: Orthorhombic

Density @ 293 K: 4.93 g/cm3

Color: blackish

[AstronautGeologist]

Basic Information

Name: Eve

Temperature min: -40.19 °C (232.96 K)

Temperature max: 149.96 °C (423.11 K)

Atmospheric Pressure: Atmospheric Pressure 507 kPa (507,000 Pa)

Atmospheric Height: 96,708.574 m

[Holo]

If you have the escape velocity of Eve, you can work out which gases will be retained.

[Brotoro]

Iodine is quite heavy, so Eve could hold onto it (as well as carbon dioxide and nitrogen...gasses typically found in terrestrial planet atmospheres).

A problem with Eve's atmosphere being iodine (aside from the general rarity of iodine in the cosmos, as the AstroGeologist has pointed out) is that it is a moderately reactive element (the least reactive of the common halogens, but still a halogen), so I wouldn't expect it to stay in the atmosphere if there is anything on the surface to react with (just as you wouldn't expect to see an atmosphere with lots of oxygen in it unless there is photosynthetic life there...or some other explanation)...unless there was some mechanism replenishing it.

I believe that Nova Silisko said something about wanting Eve's seas to be rich in stuff like Blutonium ...which has the problem that Eve's oceans would end up being huge natural nuclear reactors (assuming they contained enough neutron absorbers like cadmium and boron to keep the reaction rate from running away completely). And iodine is a volatile fission product (including both short- and long-lived isotopes), so the possibility comes to mind that maybe that's the continuous source of the iodine. I guess we would need to check Eve's atmosphere for other volatile fission products like cesium and xenon. But if this is why Eve's atmosphere is purple, it is absolutely not a friendly place. Let's hope not.

Edited June 11, 2013 by Brotoro

[dharak1]

I actually asked my science teacher about this and she said for iodine to be purple there has to be a starch reaction or something. So unless eve has something to react with it cant be iodine unless its oceans or something are made of it.

[AstronautGeologist]

The heavier elements differentiate towards the core of a planet hence most of the iodine would be in the core, just as most of the iron, nickel, gold, uranium, thorium, etc. Perhaps Eve got torn up by something leaving only the core. Of course, it wouldn't just be iodine, it would also be iron, nickel, gold, uranium, thorium etc. Iodine is also produced by neutron bombardment of Xenon which in itself is a byproduct of Uranium decay so perhaps it's the leftover of a giant nuclear reactor, note a planetary core and mantle is a giant thorium/uranium fission reactor. There's also neutrons from cosmic ray spallation where cosmic rays hit something sending neutrons flying. It would take tens of billions of years for the thorium and uranium of a leftover planetary core to decay into xenon and get bombarded into iodine so such a planet could not be part of a star's planetary system, stars don't live that long, it would have to be the leftover core of a rogue planet, perhaps the leftover core of a brown dwarf star. Short of a passing neutron star or black hole, I can't imagine what could strip the rest of such a planet away.

[AstronautGeologist]

@dharak1 I'll look into that.

[AstronautGeologist]

Question: doesn't iodine need starch to become a purple gas?

Short Answer: Iodine - gaseous, is purple. Starch makes it purpleier, purpler; more purple.

Long Answer: Starch is not required. (what's your science teacher smokin'? lol, aren't science teachers supposed to know what they're talking about?) Iodine is a gray/black solid which, when heated, sublimates; that is, it goes directly to the gas/vapor phase without becoming a liquid in between. Iodine gas/vapor is purple and so is iodine when dissolved in a non-polar solvent like carbon tetrachloride or benzene. The purple color indicates the presence of iodine and starch is not required. The reaction of iodine with starch is different; it reacts with starch to form a blue-black complex compound that isn't the same color as the purple gas/vapor.

Edited June 12, 2013 by AstronautGeologist

[AstronautGeologist]

What are the properties of this "blutonium"? I looked it up and I'm not getting anything.

[AstronautGeologist]

Originally posted by Brotoro at http://forum.kerbalspaceprogram.com/showthread.php/26296

But what DID get the KSC mission planners' attention were some measurements by Desdin that showed that the thick soup in

Eve's seas is unusually rich in the fissile element blutonium, which is necessary for making nuclear rocket engines.

Apparently, simple chemical extraction processes can separate the blutonium from the sea "water." Happily, the seas are also

rich in cadmiumium and boronate (known neutron absorbers), so there is no danger of the seas becoming natural nuclear bombs.

Below we see Desdin, our happy colonist on Eve, with the base habitat that was dropped to him in an earlier mission.

Not everyone is convinced by Desdin's reports, of course... Kerbal scientists are still hotly debating Desdin's claims that the purple chemical staining the surface of Eve is an organic compound that he says must have been deposited as tiny particles excreted from microbes inhabiting an upper region of Eve's atmosphere. But KSC officials ARE convinced about the blutonium resource, so the mission to build an Eve ascent vehicle was approved.

Interesting!

[paleorob]

Since we are pretty sure that blutonium will be a resource that can be extracted from the oceans of Eve (from the infamous resource chart), I would tend to lean towards the radioiodine atmosphere hypothesis over the atmospheric bioparticulate hypothesis.

[AstronautGeologist]

What are the possible abiotic sources for Iodine, and could such abiotic sources result in significant amounts of Iodine in a planet's atmosphere?

What are the possible biotic sources for Iodine, and could such biotic sources result in significant amounts of Iodine in a planet's atmosphere?

Edited June 12, 2013 by AstronautGeologist

[Kryten]

I've seen Iodine vapour, and it seems much pinker than Eve's atmosphere, if that makes sense.

[Brotoro]

I think the atmosphere of Eve must be purple because of suspended particulates of the same material that you find on the surface of Eve. Otherwise we need to find both a purple gas for the atmosphere and a purple solid for the surface. It's simpler if the same material does both jobs. Because solid iodine is not purple, it won't do the job for coloring both the atmosphere and surface. So...we need something else purple.

[th3shameless]

the iodine gases in the air could have somehow colored the ground through reacting with it or mixing with it

[Brotoro]

the iodine gases in the air could have somehow colored the ground through reacting with it or mixing with it

But the point is that while iodine gas is purple, I can't find any iodides or other iodine compounds that are purple. White, yellow, colorless...but not purple.

[kahlzun]

airborne organisms that are excreting the purple organic particulates.

I wonder if you'll find one-armed-one-eyed flying purple particulates?

[kahlzun]

the iodine gases in the air could have somehow colored the ground through reacting with it or mixing with it

Could the ground be white, and the purple colour just comes from the atmosphere? As in, purple light passes through, and makes the ground appear purple?

[Brotoro]

Could the ground be white, and the purple colour just comes from the atmosphere? As in, purple light passes through, and makes the ground appear purple?

If that was the case, then the ground would not look purple at night under the illumination of my rover headlights.