Titan Occupies A Solar System Sweet Spot

SocietyoftheFist writes "From an article on the BBC website, scientists have determined that Titan occupies a 'sweet spot' much like Earth. Venus is the same size as Earth but too hot so water boiled off long ago ending most geologic processes. Mars is too small to generate enough heat to keep water from freezing so it too slowed down geologically. Titan is much like the Earth with winds, rains and tectonic forces but instead of water it has an abundance of methane. Methane is liquid at the temperatures found in Titan's atmosphere and replaces water in the equation."

Comments

Hmm, methane

[Saven Marek]

Methane hey. that could be spelled "oil"

I say we go get rid of the terrorist on Titan.

Re:Hmm, methane

[ShineyMcShine]

this has got to be the best first post ever...

Re:Hmm, methane

[cyberfunk2]

Actually gasoline is typically octane.. not methane.
While crude oil does contain some methane, that is not the primary component, nor the one we use for diesel or common car gas.

Methane is very flammable.. you'd have to keep the gas compressed all the time.. seems like an awful lot of trouble.

The political motivations of your post however, are quite clear... Go post on fark if you want to start a flame war.

Re:Hmm, methane

[EtherealStrife]

Hey, don't laugh it off so quickly. Conspiracy theorists might want to consult Stephen Baxter's Titan, in which the accidental destruction of the spaceshuttle Columbia on re-entry prompts a daring mission to Titan, to prep it for human colonization / mining (and it doesn't hurt that it comes at a time when NASA's funding is being reconsidered, and the program itself re-evaluated -- yup, still talking about the book).

Published November 1, 1998.

I remember hearing about the "Columbia Disaster" and thinking damn...Baxter's gotta be shitting his pants today...

Re:Hmm, methane

[rossdee]

"Actually gasoline is typically octane.. not methane."

True, the major components of gasoline are Octane and he[iane. Of course thare are many other additives including ethano;.

"Methane is very flammable.. you'd have to keep the gas compressed all the time.."

You'd have to keep it compressed because it is a gas at room temperature, so it would take up a lot of space. Of course you could keep it in a gas bag on the roof of the vehicle like people did in WWII with coal gas.

Methane is the major component of 'natural gas' which can be used as an automotive fuel in compressed tanks (Called CNG) It could also be converted into synthetic gasoline. There is a plant that does this in NZ.

methane?

[TheAdventurer]

omg it's the fart planet!

The 14 year old cherry-bomb-in-mailbox type of rascal in me demands that we light a match and drop it on Titan. BOOM. That would be neat.

Re:methane?

[aklix]

I'm sure that liquid air will burn right up...

Re:methane?

[Anonymous Coward]

What I don't get is how is this considered the sweet spot?

Its not oxygen, its not water, its not livable, its not breathable, and I'm sure as hell that the temperature's not close to tolerable.

Re:methane?

[Tango42]

Methane only burns in the presence of oxygen, there's not enough oxygen on Titan for that. You'll have to go back to mailboxes.

Re:methane?

[dreamchaser]

There are theoretical models which postulate that life 'not quite as we know it' could evolve in a methane based ecosystem.

Re:methane?

[DrEldarion]

You're thinking too narrowly - not all life has to be carbon-based, mostly water, and oxygen-breathing.

Re:methane?

[thrillseeker]

There are theoretical models which postulate that life 'not quite as we know it' could evolve in a methane based ecosystem. Ahhh - so that's where slashdot began.

Re:methane?

[suitepotato]

Cue umpteen posts noting that there's no oxygen for the methane to combust with. Follow with posts noting the redundancy and anal nature of the preceeding posts. Follows those with posts arguing the relatively humorous nature of the posts preceeding the preceeding posts. Mix thoroughly, bake at brainstorm temperature, serves as many /.ers as bother reading.

Re:methane?

[e_xworm]

Actually that star wars scene allways troubled me...
So we have these guys here, they're in deep space no planet's anyware and they see that big round thing and what do they think it is? A moon? A moon of what?
Not that they should have said "they're heading to that small spherical space station" but shouldnt they consider it as a small planet rather than a moon?
Wow, come to think of it, this must be the worst off-topic post ever

Re:methane?

[e_xworm]

Isn't methane a little bit too flammable? Imagine that poor titanian that first discoveres fire:
"Hey look i have created..."
KA-BOOM

Re:methane?

[Skreems]

I'm not positive on the chemical reaction, but if you open up a canister of methane and light a match, you're going to have oxygen present from the surrounding air ;-). In fact, if it burns slowly instead of just exploding, that would indicate that only some of the methane is igniting at once, likely the methane next to the surrounding air, and thus mixed with oxygen...

just sayin...

Re:methane?

[ciroknight]

Oh it doesn't? Do you have a counter-example of life for us to look at that isn't carbon based, and mostly water and oxygen breathing? (well, trees breathe CO2 for the carbon content, but trees need oxidants too).

If so, please contact someone in the scientific community immediately.

Re:methane?

[Anonymous Coward]

The reaction is:
CH4 + 2O2 = CO2 + 2H2O

sheesh

Re:methane?

[ginotech]

you must have forgotten everything in the combustion chapter.

Re:methane?

[sholden]

1. Go to bookshelf
2. Take out the dictionary
3. Look up the word theoretical

Re:methane?

[Kainaw]

not all life has to be carbon-based, mostly water, and oxygen-breathing.

That is true, but you also have to take into account the fact that solid water (ice) is less dense then liquid water. We take it for granted, but think about how it affects our planet. The bottom of the ocean is not solid like the bottom of a methane ocean. They are liquid and at a controlled temperature (4 degrees celcius). How much of a role does this little oddity of water play into our planet's evolution?

Re:methane?

[dusik]

>> "...light a match and drop it on Titan. BOOM."

Did you check if there's an oxidiser on Titan? If you know that methane burns well, then why do you think it's still there in such abundance? Perhaps because there's nothing to burn it with? ;)

Re:methane?

[OohAhh]

So here's an off topic reply for you. Perhaps they thought it was a moon of the planet Alderaan which wasn't there any more?

Re:methane?

[Dun Malg]

1. Go to bookshelf 2. Take out the dictionary 3. Look up the word theoretical

No theory was presented. Speculation without a rational basis is called "imagination", not theory.

Re:methane?

[zamboni1138]

You mean "ugly bags of mostly water", right?

Re:methane?

[TheAdventurer]

Boy you guys really are nerds. I make a joke and I get a bunch of nasaly gamers dressed as Spock reminding me that it needs oxygen.

Good Intentioned Poster: Have you heard the one about the priest, the rabbi, and the black guy who are all floating down the river in a bath tub?

Slashdot Response: [insert a dissertation on buoyancy and displamcenet issues that totally sterilize the joke.]

Re:methane?

[sholden]

The english language uses words differently than science jargon defines them.

But anyway, the theory is that polylipids might be able replace proteins, but yes it's speculation based upon basic chemical properties.

Re:methane?

[lorelorn]

As far as we know, all life is carbon based, and requires both water and heat in order to exist.

There are no examples of life that doesn't have these requirements.

Re:methane?

[AstrumPreliator]

Do you have an example to prove that life must be carbon based, and mostly water and oxygen breathing? Let's face it, our little planet is unique right now. It could swing either way. One example - us - is hardly sufficient to prove a model. There are physical properties about the elements and molecules that make life possible on this planet, but only our life. Truth be told we don't quite know how life ever came into existence. Until we find another form of life that didn't come from our little back-water planet all we have is speculation.

So if you can prove the reverse, please contact someone in the scientific community immediately.

Re:methane?

[B3ryllium]

Have you heard the one about the priest, the rabbi, and the black guy who are all floating down the river in a bath tub?

As a matter of fact, I have - but I still don't get how they came across the pantyhose, the tutu, and the bubblegum?

Re:methane?

[mOdQuArK!]

As far as we know, all life is carbon based, and requires both water and heat in order to exist

Rewording that slightly, all life that we know of is carbon based & requires both water & heat in order to exist. The key phrase being "that we know of". Let us know when you have exhaustively tested every single possible physically-realisable configuration of atoms in the universe to prove that a non-carbon-based lifeform can't be created..

Re:methane?

[wackywendell]

Carbon-based: well, carbon makes a very useful element, because it is very easy to string together in all sorts of ways, attaches to both hydrogen and oxygen, and like hydrogen and oxygen is rather abundant. However, that is somewhat irrelevant, because life on a methane planet most likely would be carbon-based. Methane is CH4, and hydrogen based is out of the question, you can't string hydrogens together. Mostly water: True, they wouldn't have to be mostly water, they most likely just need a solvent of some type, methane might do the trick. Oxygen-breathing: Well, the current model of evolution includes life starting as anaerobic (not oxygen-breathing), creating oxygen as excretion, and then evolving into becoming aerobic as the oxygen built up in the atmosphere. However, they did need a source of oxygen, which water provided. I don't know what other elements besides carbon and hydrogen are available on Titan, but hydrogen and carbon aren't enough, there just isn't enough variety there for the multitude of complex molecules that would be necessary for life. Although it's hard to know what life not like ours would be like, it is highly, highly probable that they will have at least the same amount if not the same type of variety of molecules as our planet does.

Re:methane?

[rkoot]

Actually, unbound oxygen isn't a nessessity.
There's a few buggers on this planet that don't depend on oxygen.
consider the Methanogen http://en.wikipedia.org/wiki/Methanogen.
These guys use acetate (CH3COO-) as a source of carbon and energy.
they produce carbon dioxide and methane in the process.

r.

Re:methane?

[ArsenneLupin]

It also doesn't require oxygen which makes it much more useful.

"Useful" in the context of combusion means "produces energy" not "doesn't need oxygen". While your equation is certainly possible, it would actually consume energy rather than producing it.

Re:methane?

[Tango42]

I didn't say it couldn't be metabolised without oxygen, I said it couldn't burn - lighting a match is usually used to stand fire, not life... interesting twist on Frankenstein if it was.

Re:methane?

[Tango42]

You don't choose your equations, you have to stick with what actually happens. You put a match the methane it reacts with oxygen to produce CO2 and water, that's what happens, you don't get to choose. You're right, that won't work in space, that's why methane won't burn in space, which was my point - Titan, taken as a whole, is in space.

Re:methane?

[rkoot]

still, oxygen isn't a nessesity. use *any* halogen (fluorine, iodine, bromine etc) and it'll go whoosh/boom (in case of fluor probably sponaneously).
burning (or iow combustion) is an exothermic reaction between a fuel and a gas (the oxidize, usually, but not restricted to oxygen.

r.

Re:methane?

[Tango42]

True, but not relevant. Titan doesn't have enough of anything else either.

Re:methane?

[Yazeran]

Yep, The evolution of the 'cyano bacteria' (which can 'run' in both reducing and oxidizing environments, that with and without free oxygen) caused the biggest and most far reaching ecologic sdsiaster this planet has ever witnesed. Now only some deap sea hot springs (black smokers etc) and other special areas on earth exsists where the bacteria who evolved before said cyanos can still thrive (and those places can be the place for some realy bizare life forms.

Yours Yazeran

Plan: To go to Mars one day with a hammer.

Re:methane?

[Digi-John]

Why would a space station be out in deep space? In orbit around a planet or at a Lagrange point would make more sense to me.

Re:methane?

[Luminary Crush]

It's a 'sweet spot' for the chemistry and weather based on methane much as the earth sits in a 'sweet spot' for chemistry and weather based on water.

For earth, water exists in solid, liquid and vapor form, and shifts between the three, causing weather and geologic change on the surface of the planet.

This same thing is happening on Titan, but with methane.

One of the sustainers of life on Earth is the fact that water transforms itself readily and frequently. Could there be a Titanian equivalent with methane? Who knows. But for methane, this is the place to be.

Now we know...

[DrEldarion]

Methane? Ah ha, I've got it!

Cows are really aliens from Titan sent to observe us. The methane they, uh, "give off" is just a little air leak in their otherwise-perfect disguises.

Re:Now we know...

[Farmer Tim]

I believe the BBC has already reported this:

http://www.bbc.co.uk/doctorwho/episodes/aliensoflo ndon.shtml

Re:Methane!

[dot.solipsist]

No, no. I think the Font of Life is Comic Sans.

Article lacks accuracy?

[VoidWraith]

In both of their "sweet spot" scenarios, they attribute boiling water to solar proximity, but then frozen water to planetary mass. In both cases, the whole thing can be explained just with solar proximity, as it usually has been. Planets farther away have colder temperatures. Yes, its true that a smaller planet will retain less heat, but the primary factor here is still solar proximity.

Re:Article lacks accuracy?

[VoidWraith]

I know, but that's got nothing to do with a "sweet spot," and everything to do with a "sweet size." Plus, he article attributed freezing, not atmospheric retention, to planetary size.

Re:Article lacks accuracy?

[Guppy06]

"Yes, its true that a smaller planet will retain less heat,"

We don't just retain heat, we generate heat. Otherwise the earth's core would have solidified a long time ago, and we'd be very irradiated.

If a smaller planet were in earth's orbit, it might not generate enough heat on its own to thaw out of an ice age.

Re:Article lacks accuracy?

[pauljlucas]

We don't just retain heat, we generate heat. Otherwise the earth's core would have solidified a long time ago, and we'd be very irradiated.

Can you explain how the heat is generated? I always assumed that the Earth's core (and mantle) are hot because it takes a really long time for all that molten rock to cool off. All the rocks that collided together 4.5 billion years ago to form the Earth generated (past tense) a lot of heat from collisions, but there's no internal heat generator.

So correct me.

Re:Article lacks accuracy?

[JDevers]

I believe you are mostly correct. There is obviously a substantial amount of heat generated by fission, but it isn't why the Earth is still hot. Also, I don't know if anyone has ever linked the latent heat of Earth to pulling us out of an ice age which is a purely atmospheric phenomenon. It is more closely linked to water and CO2 cycling I believe.

Re:Article lacks accuracy?

[republican gourd]

I am not a planetologist, but I believe the basic mechanism is as follows:

1) The heaviest elements tend to sink downward, to the core.
2) The heaviest elements also tend to be the most radioactive (see your periodic chart)
3) Thusly, you get a concentration of radioactive elements near the core. This concentrated radioactivity contributes to keeping the core warm.

Re:Article lacks accuracy?

[Guppy06]

"The heaviest elements tend to sink downward, to the core."

But the core is a hot fluid, and warm things tend to float upwards. It's also possible for denser objects to be caught in lateral currents, thereby kept in suspension.

"Thusly, you get a concentration of radioactive elements near the core. This concentrated radioactivity contributes to keeping the core warm."

If that were so, we'd be irradiated. There's been more than enough time for the harmfull radiation from such processes to have reached the surface and killed us all.

Re:Article lacks accuracy?

[Guppy06]

" but there's no internal heat generator."

First, there's friction between the layers of gooey nougat inside the earth as they move at different velocities with respect to each other. Secondly, friction from the tectonic plates moving on top of that gooey nougat (the continents, by providing thicker insulation in parts, also assure temperature differentials in the gooey nougat, causing yet more motion). Third, tidal forces from the moon and the sun that stir the gooey nougat up as they move around (bringing about yet more friction).

Toss in the monsterous pressures down there caused by the earth's own gravity, and you have a recipe for keeping the insides of the earth warm for the forseeable future.

Re:Article lacks accuracy?

[lorelorn]

That's not the point. Surface life (which is what the postulation is all about) requires a surface that can retain heat. Generation of heat is not the issue.

The surface of Io remains freaking cold, even though that moon is the most volcanically active body known, becasue it cannot retain the heat it generates*.

*okay to be accurate the heat is generated by interations between Io and Jupiter, not by Io alone.

Re:Article lacks accuracy?

[PsiPsiStar]

The boiling point of a liquid is determined both by its temperature and the atmospheric pressure. Mars has a thinner atmosphere because it can't hold as much gas. Oxygen on Mars is too light and escapes off the face of the planet, just as Helium and free Hydrogen do on Earth.

Re:Article lacks accuracy?

[Detritus]

Lord Kelvin estimated the age of the Earth at about 20-40 million years, based on the science (thermodynamics) of his day, and how long it should have taken for the Earth to cool to its current state. He didn't, and couldn't have, taken into account decay heat from radioactive elements.

See Lord Kelvin and the Age of the Earth (PDF).

Re:Article lacks accuracy?

[fucksl4shd0t]

Not to mention newer suggestions that there's a number of slow-burning fission reactions going on at the earth's core.

However, the truth is that the inside of the planet is hollow, and populated. There's a star at the center. There's even a small moon! It's a neat place.

Re:Article lacks accuracy?

[Guppy06]

"That's not the point. Surface life"

Actually, the point of this thread was whether or not planetary mass was important in keeping $CHEMICAL in liquid state indefinately.

Re:Article lacks accuracy?

[Achra]

So.. How big would a planet need to be in mars's orbit to retain heat? It's hard for me to believe that Earth in Mars's orbit would be significantly different than Mars. Mars is significantly smaller than Earth and Venus, but I thought still a pretty sizable inner solar system planet.
Mass of Earth: 5.976e+24kg
Mass of Mars: 6.421e+23kg
Mass of Venus: 4.869e+24kg

Re:Article lacks accuracy?

[Xyrus]

The article is inaccurate.

Solar proximity is only one of the determining factors for hospitable planets.

For example, take Earth and put it in Mars orbit. You don't get a frozen barren planet. You get a cooler planet for sure, but one that would still harbor life quite comfortably.

Put Earth in Venus's orbit, and you get a waremer world for sure, but one that could still harbor life.

Earth isn't Earth just because of where it's located. Our gravity allows for our planet to maintain an atmosphere. We have enough water on our planet to maintain a regulatory climate. Our planets core is active enough to maintain a magnetic shield, as well as infuse the surface with an amount of heat.

Mars is a frozen barren world because it doesn't have the gravity to maintain an atmosphere over the long haul, let alone retain much in the way of water vapor. It's planetary core is pretty much dormant. There's nothing to regulate climate or heat. So even though the equator can reach around 60 F during th days, it loses all that heat almost as soon as the sun goes down.

Venus is a sweltering oven because it spins on it's axis once every 288 days. There is no way the planet can dissipate all that thermal energy. Even if it had an earthlike make-up, the planet would soon die in a runaway greenhouse effect due to the fact that one side of the planet was being baked for so long.

And there's always a chance that thermogenic planets exist (planets that produce enough internal heat that the surface could support life regardless of where it is located).

Location is a major player, but so is makeup. Take our atmosphere and cut it by 50% and we'd be a bit colder at night.

~X~

Re:Article lacks accuracy?

[Guppy06]

"There is a ridiculously large amount of buffer material between us and the core."

It's a lot, but it's finite and hard radiation/stray neutrons from a fission reaction active enough to heat the earth would eventually reach the surface over the course of a few million years. The energy we see coming from the sun was created millions of years ago and wormed its way through thicker and denser material before reaching the surface, but it's still enough to give us skin cancer from 150 Gm away.

The energy from the sun is different in that the magnetosphere deflects most of the harmful stuff, creating something of a plasma torch on the other side of the planet. But radiation from inside the earth would have nowhere else to go. While you do see radon in geologically active areas, you don't see volcanos dumping Mm^3 of the stuff into the atmosphere.

Re:Article lacks accuracy?

[Guppy06]

The earth is massive enough for the surface pressure of the atmosphere to be around 100 000 Pa, giving us a boiling point for liquid water around 373 K. On Mars, the maximum pressure is around 900 Pa, giving us a boiling point around 278 K (or 5 K over freezing). The highest temperature we've seen so far is 293 K, and a mean temperature of 210 K, so most surface water would quickly boil off or freeze, especially with the changing of the seasons. If Mars was massive enough to push the surface atmospheric pressure just up to 2 400 Pa (a little over twice the current pressure, but still nowhere near what we're used to on Earth), it would be high enough to keep water liquid even at Mars' hottest. You might not have precipitation and weather like we're used to, but it would still be on the surface for chemical reactions.

Re:Article lacks accuracy?

[CheshireCatCO]

Wrong on both counts, it would seem. Rather complex models of atmospheres have been done to explore what happens when you change the distance to the star. Earth at Mars's distance is (according to the models) uninhabitable or at best juuuuust barely so. Earth at Venus's distance quickly becomes much too hot. (Which is the sensible answer, isn't it? Venus is just about Earth's size, but is obviously planet hell. It would be rather surprising if Earth could be habitable there, then.)

Venus's spin has nothing to do with the high temperature. Actually, it ought to make one side of the planet hotter than the other, but it doesn't. (That's that dense atmosphere at work.) The average temperature is unaffected by spin rate, though, since temperature is basically a question of energy balance. (Input=output)

Also, Earth's interior energy does not heat the surface. (Although it does allow for a magnetic field.) At least not noticably. The incoming solar flux averages about 1300 W/m^2 on the day side of the Earth while the outgoing flux due to internal heat is about 0.001 W/m^2. Guess which sets the surface temperature.

You're right that size and composition are important, but your details are disturbingly inaccurate.

Re:Article lacks accuracy?

[CheshireCatCO]

That depends on what you mean by "heat".

Surface temperature is set by the energy balace between incoming solar radiation and outgoing radiation. Internal heat is not a significant player on any solid worlds, as far as I can think of. (This balance is not just set by solar proximity, of course. Albedo is a key player and so is the atmosphere, if it exists. The latter is why Venus is hotter than Mercury.)

The interior temperature is basically unaffected by solar proximity, but is set by internal heat sources. (Accretional heat from formation, heat from differentiation, radiogenic heat, and tidal heat from select bodies.)

The reasons Mars's internal heat has allowed water to freeze is because the loss of atmosphere. Enough greenhouse gases and Mars might be able to support liquid water at the surface. (It's looking more and more like it did, so that might is quickly becoming an "is".) But when the interal heat goes away, there is no more outgasing to resuply the atmosphere and no more magnetic field to protect from solar wind sputtering. So goodbye greenhouse.

The article is accurate for the most part. (Venus had tectonics and I'm sure Jonathan Luinine knows that. But I also know that he would know that it appears to lack *plate* tectonics, which I'll wager is what he told reporters.)

Re:Article lacks accuracy?

[Xyrus]

According to some quick calculations, Mars receives roughly 700 W/m^2 and Venus receives around 2400 W/m^2.

If Earth were in a Mars orbit, I find it hard to believe that it would just barely be liveable, especially during the Cretaceous period when CO2 concetrations were much much higher. Certainly, Earth wouldn't have had a global average of 98 F, but it would definately be a tolerable place to live.

Earth now in the Mars orbit would be chilly, but still hospitable to life. After all, we have microbes that feed off of methane ice on the sea floor. That's pretty damn cold.

Earth as it is now could be a hot but habitable planet in a Venus orbit (not necessarily for humans though). It all depends on how fast Earth dissipates heat (I'm not sure of the rate).

Which brings me to why Venus's spin does have something to do with how high temperatures formed on Venus.

Let's say Venus was a lot like Earth, with some large bodies of water. If the planet had a normal day (and the atmosphere wasn't choked with CO2), then there's a decent chance that it would be hospitable. Not to human life, as day time temps would average close to the century mark on average, but we've had life forms that lived quite comfortably in those circumstances.

But Venus has an incredibly long day. Any water or life on the day side would get baked, while on the night side everything would freeze. Any oceans on the day side would vaporize since they would have no downtime to radiate the heat back into space. When you start introducing water vapor (from boiled oceans) and higher concentrations of CO2, you get a really good greenhouse effect.

Instead of cold on one side and hot on the other, you have completely burnt all over.

Of course, this may have still happened if Venus had Earth days (depending on atmospheric content, reflectivity, etc.) but it probably would have taken a long time.

  "Also, Earth's interior energy does not heat the surface. (Although it does allow for a magnetic field.) At least not noticably."

I never said it did so appreciably, but there is some heat there. As opposed to a planet like Mars where it is most likely that no heat comes from it's core.

I'm not well versed in astro-meteorology or the models they use, but this seems like common sense to me.

~X~

Re:Article lacks accuracy?

[CheshireCatCO]

You're arguing from your gut. I'm telling you: research HAS been done. I believe it was by the Kasting group in Pennsylvania. Feel free to look it up. (The journal will be Icarus, I'm fairly sure.)

The simulations show that Earth in Venus's orbit is toast, regardless of spin rate. And at Mars's orbit it's frozen, or nearly so. (The models are a little shakey on that point, as I recall.) The atmospheric models DO account for greenhouse gases, so I trust them much more than your guesses. In fact, they dial up the gasses to maximum possibly effect to test the limits of the habitable zone.

And note that CO2 is generally a wimpy greenhouse gas and isn't very effective. Also, Earth's globally averaged temperature isn't 98 F, although I suspect you knew that. It's actually not far above freezing. (Your post has a vague implication that you think that it is that high, so I wanted to be clear on that.)

And I concede your idea about spin, but it will only matter in a narrow boundary at the edge of the habitable zone. Where Venus is, water will always be unstable, even for a fast rotator. So Venus was screwed no matter what. Models show that it goes to hell pretty fast, too, regardless of the length of the day. Farther out, things get more interesting because there will be feedbacks. (Heat on the day side will tend to redistribute itself to the night side, reducing the greenhouse effect on the day side. So it isn't clear what will happen. I don't know if anyone has modelled slow rotators at different orbital distances.)

Finally, yes, the heat from the interior is there. It amounts to about 1 part in a million compared to the solar flux, so it is irrelevent.

Re:Article lacks accuracy?

[CheshireCatCO]

Ah, I just put my finger on more of what bothers me about your slow-rotator model.

The day side's temperature shouldn't get more than 20% hotter than the global average temperature, not accounting for atmosphere feedback effects. The rotation state enters the equations as a factor of 4 (from the surface area for a sphere) under a fourth-root. A slow rotator changes that to a 2, so you get a small increase in day-side temperature. But not nearly as much as you might expect thanks to that fourth-root.

Sorry for the delay in that. You made me think for a while to spot that. :-)

Re:Article lacks accuracy?

[CheshireCatCO]

The only one of those that can generate heat (in this case, anyway) is tidal flexing. Friction converts kinetic energy to heat, but you have to supply the kinetic energy. Where do you get it from? From to heat in the Earth's interior trying to escape, causing the mantle to convect and driving plate tectonics.

Pressure does not produce heat. It in now way can supply energy. For gaseous bodies, a high inernal pressure suggests high temperature (to balance gravity with thermal pressure), but for the solid Earth this isn't required.

Finally, tidal flexing is not a very significant player for Earth. The Moon moves too slowly and simply isn't large enough to generate that much heat in the Earth. The Sun's tidal forces are every smaller, although the total power should be higher in that case. (The frequency of the forcing is one day rather than 28 days.)

It really does come down to radioactive isotopes producing heat.

Re:Article lacks accuracy?

[CheshireCatCO]

You're confusing kinds of radiation.

The kind of radiation that leaks out of the Sun's interior is light. The UV gives us skin cancer, the visible lets us see. The Earth, being much cooler, emits very little UV so we're in no danger there.

The particle radiation from the Sun comes off due to the high heat at the surface. Again, with a cooler Earth, there is little radiation and little risk. Most of what is emitted deep in the Earth is absorbed and turned into heat long before we ever see it on the surface.

Speed

[JohnWiney]

A fundamental issue, as I understamd it, is the speed of chemical reactions. Roughly speaking, chemical process speeds are related exponentially to temperature. Generally speaking, the temperatures on Titan are far to low to permit life processes anything like the sort we see on Earth. That isn't a definite "no", but any life forms would have to be radically different from anything on Earth.

Re:Speed

[s0rbix]

which is why we need to investigate it further. radically different forms of like based on methane would give us incredible insight into how life is formed.

Re:Speed

[RobertF]

Most likely, if there's any life it's by heat vents. They said Titan is geologically active, and appears to be erupting continuously. In that case, it's similar to life that exists in vents in the crust under the ocean. Those things do look other worldly, but I'd wager that its conceivable that a single-cell organism could develop by these geological hotspots.

Re:Speed

[frgough]

Chemical reactions for life go too slowly at our temperature, too, and thank goodness they do or we would all chemically react ourselves into a pile of goo in a matter of a few minutes.

You want reactions that are slow, but that can be sped up using a catalyst when necessary. That allows you to control the reactions and switch them on and off as needed. In biological systems enzymes are the catalysts.

Re:Speed

[unixbugs]

Along that note there are scales at which the elements can support an 'organic' life form, one of which is our definition of carbon based, the next level theoretically would be silicon based. This has to do with atomic structure and related harmonics of the periodic table.

I wonder if the environment on Titan would have the ability to support life on a different atomic scale. Ammonia seems to be a promising candidate on Titan.

I love this stuff!

Re:Speed

[Tablizer]

A fundamental issue, as I understamd it, is the speed of chemical reactions. Roughly speaking, chemical process speeds are related exponentially to temperature.

The South US is a counter-example. It is too damned humid there to move fast, so people just mosey on by like slugs.

Re:Speed

[idlake]

Roughly speaking, chemical process speeds are related exponentially to temperature.

Yes. What that means is that reactions that are "just right" on earth will be too slow on Titan. But there are almost certainly equivalent reactions that would be too fast at our temperatures but just right on Titan. They wouldn't even have to be radically different.

Re:Speed

[villageidiot357]

You are right about the speed of chemical reactions being influenced by temperature. Thats why you can predict the temperature from the rate a cricket is chirping. However, alot of reactions that take place in the human body won't occur readily at body temperature. To get around this problem the body uses enzyemes to provide alternative reaction path ways where the reactions are more favorable.

Re:Speed

[MichaelKaiserProScri]

Temperature isn't really an issue. There are plenty of precedents for life using enzymes to run chemical reactions at speeds other than what they would usually run. Your very body "burns" sugar enzymatically at 98.6F instead of the 450+F it would burn at if you just lit it and let it burn.

Heck, oxygen isn't even really the issue. There's a lot of energy in those hydrogen bonds in the methane (and other hydrocarbon) molecules. The hydrogen just "likes" oxygen better than it does carbon, so the oxygen is a convenient way of coaxing the hydrogens off and releasing the energy. It's not the ONLY way of getting the hydrogens off. Decomposing complex hydrocarbons into simpler ones would work in the absence of oxygen.

Provided it could get the initial energy to start the reaction, it could probably enzymatically "burn" methane at low tempature and use the energy released to sustain the reaction. It would likely "live" slower than life on Rarth does since the low temperature would likely slow down reactions. It would then pass on this initial reaction energy to it's offspring to keep the cycle going.

Improbable sounding? Well just remember that on Earth a very similar thing happened. Life didn't just fire up the minute all the pieces came together. They've tried it. Recreate the conditions of primordial Earth in a tank. You get amino acids and other "life like" stuff, but no life, at least not immediatly. Something happened to impart that initial energy to get the cycle going.

Re:Speed

[JohnWiney]

With a sample size of one, it is impossible to prove anything, of course. However, the analysis I have seen leads towards the conclusion the the Earth's temperature is a "sweet spot" that appears essential for the complexity of life reactions.

Re:Speed

[idlake]

Yeah, the same kind of "analyses" that have concluded that things can't live near hot vents, in oil, or inside ice or rock.

Re:Speed

[JohnWiney]

Not the same kind of analyses at all. Yes, if there are sufficient number of sufficiently stable suitably structured hot vents on Titan, there could be life in Titan. It seems very unlikely, for example, that life could be sustained unless such hot vents remain active over ten of thousand or perhaps millions of years. Possible, but unlikely. There is almost no evidence that such stable vents exist on Titan. As far as I know, there was never any "analyses" that life could not exist around hot vents on Earth. It was generally unexpected and unpredicted, but I don't think any well-recognized expert absolutely rejected it before the observations.

Re:Speed

[idlake]

as far as I know, there was never any "analyses" that life could not exist around hot vents on Earth

People had all sorts of crazy ideas where life couldn't exist. 70C used to be considered the limit, for example, even for simple organisms.

I don't think any well-recognized expert absolutely rejected it before the observations.

Well, your faith in "well-recognized experts" is charming but misplaced. Well-recognized experts used to think the earth was flat.

Re:Speed

[JohnWiney]

Name one.

Of course!

[jd]

Well, you have noticed the similarity between the "Men in Black" and restaurant waiters, haven't you? And you've noticed they delight in serving steaks? Well, that's what happens when the Titan aliens they've interrogated in Area 51 are finished with.

Methane doesn't replace water.

[caveat]

While the methane jokes are just HI-larious, on a more serious/sci-nerd note:

Methane is a lot less likely to be the "solvent" for life as water is. Water has a lot of very unusual properties which are important factors in the biochemical reactions of life; the most important of these is its strong polar nature. The polarity of water is a, if not the (biochemists feel free to correct me, i'm synthetic org.), major factor in protein folding; the ability of water to dissolve ionic compounds is also vitally important, e.g. nerve function. Bottom line, a nonpolar organic solvent is a *lot* less likely, if not impossible, to support life.

Re:Methane doesn't replace water.

[MichaelSmith]

The polarity of water is a, if not the (biochemists feel free to correct me, i'm synthetic org.), major factor in protein folding

I wonder if water has to be liquid for these properties to come into play. I am thinking about bacteria found inside Antarctic rocks.

Also I wonder if bacteria could create their own microclimates inside ice blocks, kept liquid by their own metabolism.

Re:Methane doesn't replace water.

[mikiN]

... i'm synthetic org. ...

Better keep your whereabouts secret or The Cadre will be after you...

Re:Methane doesn't replace water.

[suchire]

It isn't just polarity; hydrogen bonding plays a huge part in creating the entropic effects necessary for protein folding, as well as the optimal heat capacity for maintaining a stable earth temperature.

Re:Methane doesn't replace water.

[Mr2cents]

But it still remains very interesting to study. All these problems you propose are valid, but the chemistry at those places could still be very complex, and the thing with life is, once it has started its' complexity will rise with the next generations.

Our experience life is, let's face it, laughable. We only have one genesis to work with. The premise of liquid water is solely based on Earth observations. I don't know about you, but at least I don't know about any holiday resort on Earth next to a liquid methane lake. there just aren't any.

If I hear about an energy source, complex carbon-based chemicals and a liquid to mix them, then, with an open mind, I think some emerging intelligence may occur after billions of years. Even if it is a freak accident, if you believe a complex system can exist for even a few hundred millions of years without one freak accident, then you're obviously not an engineer. Maybe it will not be life as we know it, but damnit Jim, it will be alive!

Re:Methane doesn't replace water.

[flithm]

Informative post indeed.

Just thought I'd throw it out there that this assumes the kind of life we're used to is the only kind.

Although I suppose if we came into contact with radically different life forms, we might not even know they're there!

Re:Methane doesn't replace water.

[qbwiz]

It really helps if the water's liquid. Proteins have trouble folding if they're unable to move, fixed in one configuration in the crystal lattice of ice.

Re:Methane doesn't replace water.

[myowntrueself]

Then theres the lipid bi-layer that forms the cell membrane.

Is there any analog of a lipid in methane? One which can form a bi-layer bubble?

Re:Methane doesn't replace water.

[timmarhy]

there is one train of thought that life is actually a cosmic imperitive so to speak. in that if it's even remotely possible, then life will occur. the reasoning behind this is that we can find life in boiling springs, frozen rocks and many km's under the sea in total darkness. if life can survive in such conditions, then maybe it's not some rare fragile occurance, but a force in the universe which is just begging to happen anywhere possible.

Re:Methane doesn't replace water.

[Shimmer]

The thing with life is, once it has started its' complexity will rise with the next generations

This is a fallacy. There is no inherent trend towards complexity. Evolution progresses only towards adaptedness, even if it means that the next generation is simpler than the current one.

Re:Methane doesn't replace water.

[LordLucless]

Even if it is a freak accident, if you believe a complex system can exist for even a few hundred millions of years without one freak accident, then you're obviously not an engineer

Except it doesn't require just any freak accident, it would require one very specific type of freak accident to generate life. In fact, since we still don't know exactly how life is generated we really can't say what is required for it to come about.

Re:Methane doesn't replace water.

[monk]

here is one train of thought that life is actually a cosmic imperitive so to speak.

But that's metaphysics, not science.
There is a story of a puddle which forms in a hole in some cement. The puddle thinks "ooooo what a nice hole, it fits me perfectly, it must have been made for me. The puddle keeps thinking this right up until the last drop dries up.

My personal opinion is that "life" is just a word with no particular meaning. Some systems appear to be "alive" to us because we are systems evolved to distinguish food, threats and mates. We didn't have to happen, neither did pigs or mastadons or bacteria.

Since we haven't found something we want to call
life anywhere other than Earth yet, we are looking at a 0% chance based on past results. But as the stock brokers say, "past results are no indication of future returns."

My personal hope is that we find life all over the place, and more importantly that we find ourselves spread all over the place coming up with inovative ways to keep our winning streak going. I'm hoping there's some self-aware energy pattern directly descended from our earliest, single-celled grandpappy there to watch the final neutron decay, or, having found a way to make its own universe or enter others, outliving the end of this one.

Let's get to work!

Re:Methane doesn't replace water.

[wackywendell]

The one thing you seem to be missing is that 99.9% of the evidence we have shows evolution moving in the direction of complexity. We started from prokaryotic single celled organisms, moved to much more complex eukaryotic organisms, and kept going to even more complex multi-celled organisms. And even those prokaryotes and unicellular eukaryotes around today (of which there are many, ask your immune system) are on average more complex than the average of previous times. Lots of useless DNA, resistance proteins, etc. etc. that are useful.

Re:Methane doesn't replace water.

[idlake]

The polarity of water is a, if not the (biochemists feel free to correct me, i'm synthetic org.), major factor in protein folding;

Proteins fold no matter what environment they are in, they simply fold differently in different environments. There is no reason to believe that folding in solvents other than water would be any worse for evolving life than folding in water.

the ability of water to dissolve ionic compounds is also vitally important, e.g. nerve function

Organisms on Titan may dispense with all those inconvenient ions and channels and instead just use efficient organic conductors, maybe even superconductors, an option that evolution didn't have in the hot, conductive, and corrosive environments where life evolved one earth.

a nonpolar organic solvent is a *lot* less likely, if not impossible, to support life.

There is no scientific basis for such statements. It's not even clear what "less likely" means

Re:Methane doesn't replace water.

[nihilogos]

Since we haven't found something we want to call
life anywhere other than Earth yet, we are looking at a 0% chance based on past results.

From a purely statistical perspective, this is incorrect. The sample size is not large enough for any conclusions to be drawn about the frequency of life throughout the universe, or even just the galaxy.

Re:Methane doesn't replace water.

[HexDoll]

Take a look at this story on the BBC. Pelagibacter ubiquehas evolved to have a small uncomplicated genome because it lives in a very resource scarce environment where the energy expended reproducing is an important factor in survival.

Re:Methane doesn't replace water.

[Xyrus]

"This is a fallacy. There is no inherent trend towards complexity."

Obviously, you have never dealt with christmas lights.

~X~

Re:Methane doesn't replace water.

[myowntrueself]

Cool, thats what I was wondering because it sounded as if methane would support that sort of thing, the parent poster mentioned about its polarity property.

Not that I *really* understand this sort of thing; I'm a comp sci major who also sat a few cell biology/genetics papers!

Re:Methane doesn't replace water.

[wackywendell]

ha, ok, ok. Basically, life on this planet started as bacteria and now there are huge, complicated mammals on this planet, and even the bacteria on this planet are more complicated than the first bacteria. So, the evidence shows that over the past 4 billion years, evolution has moved in the direction of complexity.

Re:Methane doesn't replace water.

[monk]

From a purely statistical perspective, this is incorrect. The sample size is not large enough for any conclusions to be drawn about the frequency of life throughout the universe, or even just the galaxy.

You're right, that's probably the better point to make.

Re:Methane doesn't replace water.

[ross.w]

What you're dealing with there is entropy.

Re:Methane doesn't replace water.

[mewphobia]

This is a fallacy. There is no inherent trend towards complexity. Evolution progresses only towards adaptedness, even if it means that the next generation is simpler than the current one.

If life started as a single celled organism, then the only direction it could go is to get more complex.

I don't think evolution progresses only towards adaptedness - Look at humans. What specific task have we evolved towards? Evolution progresses only towards survival. We've evolved the brains we have because it lets us suit more situations. The more situations you evolve to suit the more complex you have to be.

Re:Methane doesn't replace water.

[dvk]

> I don't think evolution progresses only towards adaptedness - Look at humans. What specific task have we evolved towards?

Survival and propagation on genetic level. Same as anything else. Although some theories postulate that we evolved as a supreme method of creating umbrella coctails.

> Evolution progresses only towards survival.

"adaptedness" which you rejected above means survival. However, there's a balance between survival in a current environment (ensuring survival/propagation of the organism carrying a gene), and survival in the whole system, which means being able to change as the system parameters change.

Look at sharks - they are already supremely adapted to their environment and have no "need" to progress. And if that doesn't convince you, look at viruses and baceria. neither saw it fit to become extinct just to suit your aesthetical need for more complexity.

> We've evolved the brains we have because it lets us suit more situations.

Not really. We evolved the brains we have because the balance between avialability of better food (meat), and needs to get it (socializing more) allowed the genes which cause the complicated brain to be more successful in that *particular* environment.

> The more situations you evolve to suit the more complex you have to be.

Cocoroaches are suitable to many more environments/situations than humans.

Which is why they survived almost unchanged for a VERY long time and humans were on the verge of extinction many times; and still are reasonably close to it - till we develop viable self-sustainig off-earth capability, since we are rather badly suited to survive as a species if environmental conditions change dramatically ala 65Mil years ago.

-DVK

Great!

[Baloo Ursidae]

Now we have a lifeless planet full of transit bus fuel. Just have to get it here...

Re:Great!

[MichaelSmith]

Now we have a lifeless planet full of transit bus fuel. Just have to get it here...

You only get energy out of the methane if you combine it with oxygen. Personally I need oxygen to breathe. Also you would be importing carbon from Titan, which would become carbon doxide on Earth.

Re:Great!

[Farmer Tim]

Personally I need oxygen to breathe.

Then I assume you don't often travel by bus.

Let me guess...

[Savage-Rabbit]

...your real name is Gary Larson?

I wonder.

[Poromenos1]

If there are two planets capable for sustaining life (well, one is. I don't know about Earth), how many are there in the entire universe?

Re:I wonder.

[Guppy06]

Low. From what I understand, most of the star systems we've been able to watch closely have superjovian planets in orbit around them, and they don't bode well for life. Jupiter itself is yet another "sweet spot," big enough to sweep the solar system of most of the extinction-causing comets/asteroids/etc, but not so big as to suck us up. Planets that are 10's or 100's of jovian masses don't allow for many other planets (let alone rocky planets with a fluid iron core at the correct distance from the system's star) to coexist.

Re:I wonder.

[b100dian]

most of the star systems we've been able to watch closely have superjovian planets in orbit around them
I suppose that's the reason we discovered them. And 'watch' is not an appropiate word for describing 'supposing planet when star is wobblig'

Re:I wonder.

[Mozk]

"It is known that there is an infinite number of worlds, simply because there is an infinite amount of space for them to be in. However, not every one of them is inhabited. Therefore, there must be a finite number of inhabited worlds. Any finite number divided by infinity is as near to nothing as makes no odds, so the average population of all the planets in the universe can be said to be zero. From this it follows that the population of the universe is also zero, and that any people you may meet from time to time are merely the product of a deranged imagination."

- Hitchiker's Guide to the Galaxy

Re:I wonder.

[nihilogos]

From what I understand, most of the star systems we've been able to watch closely have superjovian planets in orbit around them

That was a long time ago, and it was only because the doppler-shift techniques used for detecting them were intially only sensitive enough to detect massive super-jovian planets.

If you take a look at an extra-solar planets catalog you'll find lots of sub jovian planets. Note that a lot of them have pretty short periods, but again this is more a feature of the way they're detected, and doesn't say anything about a typical star system.

Extra solar planetary detection techniques are still being refined, and many astronomers expect to be able to detect earth size planets at earth-like distances from their suns. I've even been to a talk by an astronomer who was enthusiastically discussing the possibility of spectral analysis of these planets to determine what their atmospheres might contain.

Actually living on Titan

[Mishra100]

I just don't understand where scientists think that it would be possible to live on one of these moons. From the article,

"But David Grinspoon of the Southwest Research Institute says organisms could occupy specific niches, such as hot springs. They could use acetylene, in reaction with hydrogen gas, to release enough energy to power metabolism, and possibly to heat their environments. "

I just don't see this happening. The reason that earth can be heated is because of the sun. When you stand outside you can feel the heat that is generated from the sun. The earth also had a hot core but that isn't near enough to keep it heated. Plus the fact that the hot spots on Titan that are generated by its own core, are going to be tiny. You are not going to be able to eat or drink as there is no resource for food. These scientists really have big dreams. They make this stuff out to be like a real fairy tale... Its nice to know some things about the planet but when they try to convince themselves that it is habitable then it just gets a little silly.

Re:Actually living on Titan

[MichaelSmith]

I just don't understand where scientists think that it would be possible to live on one of these moons.

They are not saying that humans could live in the open on Titan. Only that small colonies of organisims could live in some isolates spots on the surface.

Plus the fact that the hot spots on Titan that are generated by its own core, are going to be tiny.

Tidal heating from Saturn makes geothermal energy a better prospect on Titan than it is on Earth.

You are not going to be able to eat or drink as there is no resource for food.

Humans could bring along their own energy sources. Native life (if it exists) would have its own ecology.

Re:Actually living on Titan

[Mishra100]

I do understand that most of their goals are just to find a real organism... But I believe we have already solved the "orgamisms on other planets" mystery by the dead bacteria on the rocks of mars. I should have specified, but I am leaning toward a complex organism. I have total confidence that some kind of single cell or a small multi cell organism could adapt to Titan's environment.

Re:Actually living on Titan

[MichaelSmith]

I have total confidence that some kind of single cell or a small multi cell organism could adapt to Titan's environment.

You are more optimistic than me. I think in 50-100 years we will know whether Life As We Know It is unique to Earth, or a more general (geologic?) attribute of matter.

Re:Actually living on Titan

[Guppy06]

"The earth also had a hot core but that isn't near enough to keep it heated. "

It's hot enough to keep certain organisms that rely on chemosynthesis alive at the ocean bottom, where no radiation from the sun reaches. There's little reason to believe this process couldn't happen on any reasonably volcanic body.

Re:Actually living on Titan

[LifesABeach]

The fundimental problem we have is a lack of evidence of the existance of non carbon based biologies on this planet. To think that it takes water, and carbon to make elementary life is niave; But at this point, we have nothing to compare to. There is no paper published on this planet that could support processes of non carbon based biologies, and still stand up to unit testing by any interested party. The only known way for us to know better is by some form of contact. Personally, I would prefer if contact were made using long range passive mode telescopes under human control.

Re:Wow!

[KingSkippus]

Titan is perhaps the most Earth-like place in the Solar System other than Earth

Has anyone considered that maybe Earth is just the most Titan-like place in the Solar System other than Titan?

Methane ice worms living on Earth

[kevin777]

Maybe we should be looking for some life forms similar to these: Methane Ice Worms

Image here.

Text:

Methane clathrate deposits in the ocean floor have been found to be inhabited by polychaete worms of the species Hesiocaeca methanicola. The worms colonize the ice-methane solid and appear to survive by gleaning bacteria that in turn metabolize the clathrate. In 1997, Charles Fisher, professor of biology at Penn State, discovered this remarkable creature living on mounds of methane ice under half a mile of ocean on the floor of the Gulf of Mexico.

Re:Methane ice worms living on Earth

[MichaelSmith]

Image here.

I hope that is an electron micrograph you have there. Otherwise I am going to cut down on my enthusiasm for Titan exploration.

Cue James Cameron.

From the pictures

[CiXeL]

the probe brought back. There are water ice pebbles everywhere.

You could extract the oxygen and hydrogen from the water ice pebbles or merely use it for drinking water or growing plants.

Electricity and heating would be supplied by the frozen natural gas present EVERYWHERE.

You just get the fire started and use material for insulation and you could live there and grow vegetables under metal halide lighting from the generators burning natural gas.

Of course you could do all this but it wouldnt be very interesting. Titan is almost pitch black to the human eye. You'd have to bring a flashlight everywhere making things really creepy. There would be very little to explore, it would be about as interesting as exploring ice caves in antarctica. It would be interesting to see if you could sail on the hydrocarbon lakes though but try sailing with a flashlight.

What benefit would living on titan be other than to say we did it?

The only benefit i can see to this is to mine the moon via a assembly line of robots picking up and dropping off shipments of hydrocarbons to earth. But we would be changing earth's atmosphere with unpredictable results as we'd be adding even more greenhouse gases and carbon to it.

The only use i could see to living on titan would be as a hydrocarbon miner. Theres really no other reason of interest to be there.

Re:From the pictures

[ikkonoishi]

Just make sure to bring a lot of oxygen with you to burn the methane with.

Re:From the pictures

[ifwm]

"The only use i could see to living on titan would be as a hydrocarbon miner. Theres really no other reason of interest to be there"

S-C-I-E-N-C-E

That's reason enough.

Well...

[Esteanil]

One of my favourite movie quotes:

"There are 400 billion stars out there, just in our galaxy alone. If just one out of a million of those had planets, and just one in a million of those had life, and just one out of a million of those had intelligent life, there would be literally millions of civilizations out there." - Contact

Try this picture instead

[CiXeL]

http://www-gerg.tamu.edu/photogallery/submarine/a1 .jpg

http://images.google.com/images?q=methane%20worms& hl=en&lr=&c2coff=1&sa=N&tab=wi

I side with

[CiXeL]

it being a more general geologic attribute of matter.

Take a look at calcium for example. Have you ever noticed how coral skeletons share ALOT in common with limestone formations in a cave? It's just the structure calcium follows, perhaps the corals just take advantage of this fact and nurture it's natural crystalline form to create their skeletons. Some formations in caves are so spot on that they refer to the formation as 'cave coral'.

Re:Wow!

[AvitarX]

Not true at all, something could be almost exactly like Titan, but slightly less lik Earth than Titan is.

P=>Q != Q=>P

you

[CiXeL]

can extract it from the water ice. all you need is a small amount in the beginning to start the fire.

Re:you

[ikkonoishi]

And to extract it from the water ice you need fire to melt the ice and electricity to seperate the oxygen.

It takes 118 kcal to turn two H20 molecules into one 02 molecule (I'm ignoring the hydrogen as waste for the moment.)

You need two O2 molecules to react with one molecule of methane. This reaction will produce
191.6826 kcal.

Which means that it would take a net energy input of 44 kilocalories per each molecule of methane that you burn.

You better make that a large fire to start with because it will only get smaller the more you use it.

YHBT. HAND.

[rpresser]

A bit clumsy, but classic troll style.

Boil point of methane...

[cyberfunk2]

Sure... sounds great.. but as far as I know... methane boils at -161.45 C (111.55 K). That's not a very sweet spot for most biological systems I can think of.

Re:Well...

[tftp]

Movies are not often made to serve as math textbooks:

400e9 / 1e6 = 400e3 stars with planets;
400e3 / 1e6 = 0.4 planets with life;
0.4 / 1e6 = 0.0000004 planets with civilization(s).

So it's 0.00004% of one civilization, and not "millions" as you cite. You need to gather 2,500,000 of "our galaxies" to get to one civilization, and you already have one, so go and get another 2.5 million of galaxies if you need aliens.

Typo.

[Poromenos1]

Right, that was supposed to read "two planets in the same solar system".

Pointless what-if?

[PromANJ]

Sometimes I've wondered what would happen if we could (magically) replace our moon with Titan. It's larger than the moon so tidal effects and animal life here on earth will be affected of course, but what would happen to Titan's atmosphere? Huge greenhouse effect?
Europa would be an interesting candidate too... but maybe this sort of speculation belongs in the 'Who would win: Skeletor vs Dr.Doom' category.

Re:Pointless what-if?

[sysjkb]

but what would happen to Titan's atmosphere? Huge greenhouse effect?

Possibly. But not for very long, at least in the geological sense. Titan's able to maintain its dense atmosphere because it is so bitterly cold. The kinetic energy of its atmospheric gas molecules is not very high, so Titan's weak gravity is able to hold onto them. With significant heating, the atmosphere would bleed away.

Quite a lot of Titan is made out of ices. These will replenish the escaping atmosphere, for a while. But it also means that Titan's going to be steadily losing mass; as it loses its mass, it further loses the ability to hang onto its atmosphere.

Mars' escape velocity is 5.0225 km/s, and, starting from a colder location than Earth, has still lost most of its atmosphere. Escape velocity on Titan is 2.6452 km/s, barely stronger than our Moon's.

Sure about Venus?

[ardor]

How is this meant with the boiled water? That it boiled because of the greenhouse effect? I read several times that Venus would be habitable (although surely not very pleasant, and mostly a desert world) if the greenhouse gases weren't there, and a earth-like atmosphere would be in their place.

Re:Sure about Venus?

[lorelorn]

Venus would probably be habitable if it had an earth-like rotation. But it turns so slowly that a day is slightly longer than a year.

The additional heat that it receives from the sun, combined with that length of exposure to it, meant temperatures soared.

The atmosphere is mainly Sulphur Dioxide. The planet has been wrought with volcanism in the past, so much so that the whole surface is about the same age.

Any water Venus may have had is long gone.

The thick atmosphere acts as a blanket, trapping the heat it receives from the sun, basically making the planet is its own pressure cooker. Every so often, it must 'boil over' in a colossal volcanic episode.

Re:Sure about Venus?

[DiscoOnTheSide]

unless you've got an adimantium spine and legs I don't think humans will be living on Venus. The gravity alone is enough to crush a man like a empty soda can. The environmental pressure doesn't help either... from my understanding.

Re:Sure about Venus?

[The Master Control P]

Venus' gravity is 10% LOWER than earth's; It's atmospheric pressure is equal to the bottom of earth's oceans, only with sulphuric acid.

Re:Sure about Venus?

[DiscoOnTheSide]

Thanks for the correction. I was trying to remember from high school (six years ago)... I just knew there was "man == crushed" in relation to Venus, I just forgot the vector of the crushing :)

Re:Sure about Venus?

[Xyrus]

You're forgetting speeding up the rotation to be about an earth day.

Green house gases or not, any planet that has a 288 day long day at venus's orbit is going to be baked planet.

Get rid of the green house gases, speed up the days, and add an earthlike atmosphere and water and you basically get a warmer Earth. Temps at the equator would most likely be too warm for most people, but the more northern and southern latitudes would be quite liveable. And the extreme latitudes would probably be no different than the northern US.

~X~

Re:Sure about Venus?

[denis-The-menace]

Too bad there no way to send enough stuff to neutralize the Sulphur Dioxide acid in the atmosphere. I'm sure in about 2-3 hundred years, we'll be thinking about that...

So, how many galaxies are there?

[Granis]

Im not sure the quote implied that there should be millions of civilazations solely in our galaxy. So if we asume the estimated number of 125 billion galaxies is somewhat correct, we are not that far off from millions of civilaztions using these calculations.

Re:Methane!

[hunterx11]

I believe you misspelled "death."

Re:What about Uranus?

[JebusIsLord]

Rectum? Damn near killed 'em!

Offtopic but....

[Omnieiunium]

Quick get the vinegar!

A Space Odyssey

[exnuke]

Wasn't this a theme in one of the 2001+ A Space Odyssey books?

Evolution and complexity

[Baron_Yam]

I believe that complexity will tend to increase in an evolving system.

As long as everyone's asexual and existing on sunlight, it's all good, but the moment you get a predator/prey split, you have an arms race.

Re:Evolution and complexity

[mOdQuArK!]

I believe that complexity will tend to increase in an evolving system.

Dunno 'bout that - in an energy-starved environment, it is probably more likely that organisms might evolve to become SIMPLER, since fewer concurrent biological processes would probably require less energy & maintenance to survive. Just depends on what kind of environmental niche you're trying to survive in.

Re:Evolution and complexity

[flyingsquid]

As long as everyone's asexual and existing on sunlight, it's all good

What about asexual and shunning sunlight, like slashdotters?

Re:Evolution and complexity

[ModMeFlamebait]

Well the /. community doesn't seem very sophisticated either ;P

Re:Evolution and complexity

[dvk]

You may also believe in the Great Pumpkin.
Mathematical rule governing evoluion (mostly, game theory), have NO bias towards complexity or simplicity. Whichever is most adapted to the environment and most stable in it, wins.

Article assumption

[lorelorn]

The article is making a pretty long assumption in equating 'habitable' with 'geologically active surface'.

Surface life may well prove to the the rarity.

Somewhere like Ganymede, or Europa, has a far greater habitability beneath the surface.

Sub-surface regions seems generally more likely to allow life to get started than surfaces. A bit of activity there is good, as life thrives in changing rather than fixed environments (as far as we know).

Even life on earth began below the surface, in the oceans.

Sub-surface is where we may find life on Mars, there's no question of life on the surface there.

Captin, I fail to see the logic of this...

[Spoing]

While you do have a propensity towards green women, the smell captin...how do you get past the smell?

Something doesn't make sense here.

[techno-vampire]

From TFA:
Venus is about the same size as Earth. But it is so close to the Sun that any water it had must have boiled off. As such, there is no hydrological cycle and no tectonic activity, says Lunine.

I'd really like to know what connection Lunine thinks there is between tectconic activity isn't related to water in any way. Living as I do in Los Angeles, I'm rather familiar with it.

Re:Something doesn't make sense here.

[stevelinton]

Surprisingly, I think there is quite a lot. Most of the minerals that make up Earth's crust contain water, and water, under pressure is drawn down into the crust at spreading faults. Also the carbonate minerals would not exist without long-lasting oceans where CO2 and silicate rocks can slowly combine. These hydrated and carbonate minerals act, I think as a lubricant to plate movements. I am not a geologist, but I'm sure I read this somewhere once. I can't quickly find confirmation.

Re:Something doesn't make sense here.

[Yazeran]

It's correct that fault moovement and plate tectonics does not require water or other fluids, but in the majority of cases large shear-zones and falut systems show that water or other fluids (CO2, SO2) may have contributed to the ease of moovement. For instance in many thrust fault systems the sole throust is often located in shales which is rich in hyrdous minerals such as biotite, muscovite, chlorite or clay minerals. These minerals often act as the geological equvivalent of grease.

In the case of thrust faluts / shear-zones in sand stones or quarzites, it is also believed that small amount of H2O molecules within the quarz structure may facilitate crystal deformation by breaking Si-O-Si bonds close to the dislocations in the crystal structure.

Yours Yazeran

Plan: To go to Mars one day wiht a hammer.

Re:Something doesn't make sense here.

[techno-vampire]

No. The plates don't slide over each other, they grind. No lubricant is needed.

subject here

[baudbarf]

So... our early Titan colonies will be plastered with "ABSOLUTELY No Smoking" signs.

Re:BRING EM ON!!!!!

[X0563511]

You know what they say about pride. You know, in the Bible?

Vonnegut knew this 40+ years ago....

[coltrane679]

So should I be expecting breakthroughs on "Ice Nine"-like substances soon?

Re:Vonnegut knew this 40+ years ago....

[Hosiah]

*tweet!* Literary reference on Slashdot! Ten minutes penalty for talking over everybody's head!

Folks, Vonnegut is "Kurt Vonnegut, Jr.", the referenced work is "The Sirens of Titan", and the "ice-nine" reference is from another book: "Cat's Cradle".

In "The Sirens of Titan" (been years since I read it, so I'll try my best), one of Vonnegut's earliest works, much is made of the notion that Titan enjoyed conditions similar to Earth's as the article states, and so some of the action takes place on Titan, which is predicted to be where the book's protagonist, Rumford, is going to die. If I'm not hallucinating, quite a bit takes place on Mars, as well, involving a massive militray operation and some of the most insanely infectious rhyming ditties ever written. And I remember something about a wild party with a piano pushed into a swimming pool, beautiful creatures called harmoniums, flying saucers, chrono-synclastic infundibulum, and the repeated theme-invoking line "Somebody up there must like you!" Vonnegut students will recognise many of the elements of his life's work born in this novel.

Sheesh, I miss that book, now. I'm going to have to dig it up again.

Life from 4 elements?

[Sky Cry]

Titan is much like the Earth with winds, rains and tectonic forces but instead of water it has an abundance of methane.

So to get life you need 4 elements?
Wind = Air;
Tectonic Forces = Earth;
Liquid Methane = Water;
And Fire would be... Required temperature or lightning?

Storm. In an ocean or just on a coast lightning striking something? Perhaps that's how life is born?

Not that I have any idea what I'm talking about... :)

Re:Life from 4 elements?

[chawly]

Not that I have any idea what I'm talking about... :) Guessed as much - but I understand completely. There are moments when you've just got to say something.

Wha? No Lifeforms?

[gameboyhippo]

Hmmm... You'd think that after 65 bazillion years, a lifeform would have evolved that uses methane instead of water. Ah well...

Re:Wow!

[tootlemonde]

Consider: (A) chimpanzees are the most human-like of the primates vs (B) humans are the most chimpanzee-like of the primates.

(A) asks us to consider the human characteristics of the chimp while (B) asks us to consider the chimp characteristics of the human. (A) and (B) broaden our perspective on humanity in different ways.

In comparing Earth and Titan, looking for Titan-like characteristics on Earth may lead us to discover new features of Earth, which some would argue is more useful than discovering new features about Titan.

Re:What about Uranus?

[Cro Magnon]

I'm sure Uranus has plenty of methane!

Re:What about Uranus?

[WormholeFiend]

that depends on the type of bacteria in there

Sources?

[FurryFeet]

From the article:
"From an article on the BBC website, scientists have determined that...

Scientific work keeps getting easier and easier.

Re:If a tree falls...

[Farmer Tim]

If you fart in a methane atmosphere, does it smell?

Do you mean the fart or the atmosphere?

Either way, the answer is no: if you're attempting to breathe pure methane you won't be able to smell anything (not for more than a few seconds, anyway).

Re:At the risk of sounding risque...

[Farmer Tim]

They were considering calling it the "Genesis-spot", or "G-spot" for short, but then they would have run the risk of never being able to find it...

Re:Wha? No Lifeforms?

[Farmer Tim]

Titan has highly evolved indigenous life, but they don't want us to know they're there in case we stink up the place with all our oxygen...