Just got to thinking about some of the problems that may have to be addressed if & when we ever try to visit Titan in person.
The first thing that comes to mind is what might happen if some Titanian air gets inside an oxygen-rich manned spacecraft, say from minor airlock residue. I imagine that the explosive potential of some of the trace gasses is pretty high, and there's probably also a significant risk of poisonous compounds as well. So, here are some tenative requirements:
1. REALLY efficient air-scavenging airlocks.
2. Surface suits that can't trap external gasses in creases, folds, etc.
3. Spark-proof electrical/electronic everything.
4. Smoking is strictly forbidden (with apologies to the entire 1950s SF movie genre!)
Gotta be more...any ideas?
In reference to your item #4... here's something from 1960. There was a TV show that tried to "accurately" portray man going into space and to the moon. Here's the lead actor of that series showing he has the right stuff as a macho astronaut... Well... it was 1960, after all. Guess no "lighting up" on Titan. ('Course there always is niccotine gum)
You definitely want a very efficient air filtering system. Obvious flammability aside if enough Titan air got into an enclosed environment, you also have to be concerned about the amount of benzene that a settler would come into contact with: http://www.scorecard.org/chemical-profiles/summary.tcl?edf_substance_id=71%2d43%2d2
I would love to go, but I'd prefer to be inside some submarine-like object rather than any kind of body suit.
I find it compelling that you could go around on Titan, pick up "rocks" you find interesting and when you get back to the ship, all those rocks just melt away under earthly temperatures. There's something about the fact that entire mountains, everything you see there would just melt if you held it in your hands long enough. Provided you had big enough hands...
An ocean world in out mindset, yet rock solid... Not to mention even more extreme cases like Triton!
The really compelling thing (offset by many hazards) is that the pressure is actually okay for people. That makes it unlike any other solid surface-locales in our solar system.
That would allow for some flimsy suits if it weren't for the extreme cold. Of course, if we sent Minnesotans to Titan, they'd only need scuba gear and a warm hat.
A slightly higher internal than external pressure would deal with most of the issues of contamination, of the interior.
Jon
What would be the physiological effects of living at 1.6+ Bar?
I was thinking that you could get away with basically a 'warm suit' with breathing gear ( i.e. the Baxter suggestion in 'Voyage' )
HOWEVER.....
The only way to not contaminate from outside to inside the module via the airlock would be to evacuate it to as near a vacuum as you can at each cycle..
i.e. people put on suits, get in. 'habitable' air then pumped out into a pressure vessel so the airlock is at as near a vacuum as can be made.
THEN - you repressurise with 'titanian' air up to titanian pressue.
On the way back in - shut the door, pump out to a vacuum dumping it to the atmosphere outside, then represurise with the air evacuated before the EVA began...that would minimise the cross contamination in the meantime
BUT
It then means you have to have an EVA suit that can manage a near vacuum so it's going to look more like a modern EVA suit rather than something more minimal that one might immediately assume would be enough for Titan.
maybe
Doug
1.6+ bar and mostly nitrogen to boot. If the lander & EVA suits were pressurized at that level, it sounds like the crew could get a BAD case of the bends when they return to the mother ship unless they decompress...better add a zero-gee decompression chamber to the shopping list!
A vacuum capable airlock might be rather heavy to drag all the way to Titan, maybe the airlock could be a conformal bag, and the pressure difference could squeeze the atmosphere back outside.
Residual gases would still be present but could be dealt with something not too dissimilar to the lithium hydroxide packs, just use a different chemical for the hydrocarbon smog absortion you want.
I suspect flammability won't be much of a concern due to dilution below the ignition concentration (atmosphere is mostly N2 in any regard), but I suspect the smell of the Titanian atmosphere will be hideous.
Yeah, I suspect that the funk factor of Titan's atmosphere will be pretty significant. At least that will provide some good leak-detection capabilities!
From the Titan chapter in The New Solar System, I see we might expect besides the nitrogen, methane and argon, to find methyl radicals (CH3), ethane, acetylene, ethylene, polyacetylene, cyanide, and various breakdown products of several of them. I suspect Cassini will be casting a far better understanding of the atmospheric constituents.
It may be possible there is still some ammonia extant there too, perhaps most of the nitrogen in the atmosphere is from dissassociated ammonia after all, and it might be clatharated with the water ice.
I'm still thinking it will be stinky there.
Oh, okay; so maybe the pressure differential isn't a big deal, then. Thanks!
I have no idea how efficiently Titanian air could be scrubbed from an airlock, nor how long it would take. However, if pressure turns out not to be too big an issue physiologically, then keeping the lander cabin at a slightly higher pressure than the outside as you'd suggested before should stop most unwanted influx.
Here's another issue: How will they generate electricity? Solar cells are out, obviously. Would a whole bunch of RTGs do the trick, or would they need a somewhat larger nuclear power plant? (Of course, by the time we're actually able to do this we may well have compact fusion power sources...here's hoping! )
Come to that, would it be worthwhile to haul in a bunch of oxygen & run fuel cells? Are there some easy ways to liberate H2 from Titan's surface compounds? Or, would it be simpler to "burn" some of the simpler CH compounds as conventional fuels using our oxygen cache?
How will the astronauts will be able to talk to their familiars, relatives, friends and lovers since the Earth and Saturn are separated by a varying distance between 1,411,725,400 km to 1,576,725,400 km (the communications signal will take between 78 to 87 minutes depending to the orbital Saturn and Earth position around the Sun).
It is possible to overcome the distorsion of telecomunications. How?
Rodolfo
Easily. They will not talk. They will send messages.
Yeah, on pretty much any body but the Moon real-time comm with Earth just ain't happening...unless you got a really good tachyon receiver/transmitter...
JC's comments were quite interesting. Sounds as if the expedition could harness indigenous resources rather easily if suitably equipped. This may prove attractive to commercial interests as well (al a Clarke's Imperial Earth). I'm sure that once the Moon and Mars are colonized Titan & Saturn's rings (and a nod here to Asimov's The Martian Way) will become the Solar System's Saudi Arabia for volatiles.
Reviving this thread just because it's interesting, and also for a question to anyone with hazmat experience: How do you scrub dangerous heavy organics out of an airlock, or off of spacesuits?
I suspect that Titan may have some of these; in fact, it may have some compounds we've never encountered before. Would any Titanian EVAs require, say, a wash-down of the suits with acetone plus some sort of purge procedure before the astronauts would be safe to re-enter the lander?
Sounds extreme, I know, but there well might be some very potent organic poisons in the Titanian environment; never too early to think about countermeasures.
Look up how much effort they took to make sure there was no NH3 on the spacesuits after recent ISS spacewalks involved in cooling loops
Doug
Great, interesting thoughts as per usual, Mike! Demanding procedures to be sure, but clearly practical.
Is the cold really that big a problem, though? I was thinking that the habitable enclosure(s) could be built like giant Dewar vessels with a vacuum layer between the inner & outer shells.
In fact, this paradoxically might require a cooling mechanism to keep the interior okay, which might provide a serendipitous benefit. I see a series of "heat pipes" (thick copper cables?) from the interior vessel out to the surface, where they're hooked to ice melting/water capturing devices...waste heat doesn't need to be wasted...
Realising that Titan's atmosphere is 98% plus nitrogen, will oxygen released by any habitat be able to ignite some of the methane (drizzle) or to put it another way are there any sources of ignition that might cause the oxygen to burn?
Roy F
Only thing I can think of would be an electrical problem like a broken wire touching the superstructure, arcing & sparking. However, there are likely to be many such interfaces, so the problem becomes keeping the internal atmosphere isolated from the external interfaces; not particularly easy.
The good news is that if the habitat has positive pressure as Mike suggested then you basically get a jet of flame shooting outwards at the joint; no interior fire. Bad news is that this could still cause one hell of a lot of damage, and might be difficult to extinguish.
Combustion is not my field but I'd be surprised if 2%, or even the saturation level of 5% or so methane would be a sufficient concentration to support combustion with oxygen, especially starting from cryogenic temperatures. Assuming the Titan base used a normal terrestrial oxygen/nitrogen mixture the risk would be even less. Cold nitrogen is a pretty good fire extinguisher. However you wouldn't want your oxygen tanks to be struck by lightning during one of those once per millennium downpours!!!
Ah. Then we need to just ground the hell out of the place....
Thanks for the replys all. I feel a lot safer now about going outside to look at one of these methane/ethane lakes. And the nice slow moving waves
Roy
Eek. So, outside-only booties & gloves stowed in the outermost airlock might be a very good idea, then? (Don't know what to do if anybody fell down outside & got this stuff on their suit, though...maybe an entire overgarment is the answer?)
EDIT: Got it! One stage of the ingress process should be pure N2 @ 300K to evaporate all this crap over a suitable (ta-da, da!) interval, then purge it out...afterwards, normal re-entry.
EDIT2: The process of going back inside is going to be a LOT like standard military chemical warfare decontamination procedures; gee, what fun.
20 % O2 would seem excessive (and probably unhealthy) at 1,6+ atmospheres. 10 % should be enough for breathing as well as decreasing fire risks and the quantity of oxygen needed.
As for leaks from an overpressure habitat it seems likely to me that small leaks might well be self-sealing since the water and the CO2 in the interior atmosphere would freeze instantly at Titanian temperatures.
Hey, that's a great point about self-sealing leaks, tty! Guess that periodic inspections/maintenance would catch these so the crew could spackle them over.
Hot wiring faults to the outside are still worrisome, though. Might be best to have all that stuff completely outside the main habitat with its own power supply and an RF link to the inside, and THAT thing would have to have some serious ground-fault interrupt protection.
Hydrocarbon solvents have a very low electical conductivity. Flowing hydrocarbon solvents (like methane, I suppose, but more OSHA data exists for hexanes) tend to build up static charges.
I wonder if a methane rain event on the outside of the habitat would build really impressive levels of static charge? In the "natural" environment, I also wonder if methane flowing along a Titan river stream might also build up an impressive static load.
"Solvents and fuels produced from petroleum (e.g., benzene, toluene, mineral spirits, gasoline, jet fuel) can build up a charge when they are poured or flow through hoses. They tend to hold a charge because they cannot conduct electricity well enough to discharge when in contact with a conducting material, like a metal pipe or container, that is grounded. When enough of a charge is built up, a spark may result. If the vapour concentration of the liquid in air is in the "flammable range" and the spark has enough energy, a fire or explosion can result."
Source: http://www.ccohs.ca/oshanswers/prevention/flammable_static.html
Since there is no oxygen in Titan's atmosphere, fire or explosion is not an option. But could "ground lightning" or spark discharges occur in the flowing streams?
-Mike
Think that would depend on the composition of the surrounding terrain, which is probably water ice with a lot of organic impurities (my guess is that on Titan H2O takes the role of SiO2 on Earth). Liquid water on Earth is significantly conductive only when it has dissolved salts or metallic ions, IIRC; don't know about ice. If the channels are carved out of good insulators, though, there well might be a good-sized charge in the fluid (and maybe also the atmosphere itself at times?)
Scary thought, though; in addition to grounding the hell out of the habitat, surface explorers may well have to have conductive suits with grounding straps dragging on the "soil" to avoid being zapped! (I have a mental image of spacesuits with dragging tails, but it's almost too stupid-looking to bear...beats blowing up, or frying the suit electronics, or even being electrocuted, though.)
Anyone else getting surprised at how un-easy surface exploration of Titan may turn out to be? That nice, thick atmosphere seems to have led to a false sense of security...
All in all, though, Nick, Titan offers more of the raw materials humans would need to create a self-sustaining colony than just about any other body in the Solar System (except for Earth).
There are all the elements we need to survive -- specifically, carbon, hydrogen, oxygen and nitrogen -- in great abundance. The only thing in short supply is a good power source. Yes, if you crack enough oxygen from the water ice you'd be able to burn a lot of the hydrocarbons, but that burning would generate less energy than what you'd need to crack that much oxygen out, I fear.
The one thing we'd need to import from Earth is a good energy source to make Titan a good place for human habitation. Unfortunately, the only thing I can think of that would work well there would be nuclear energy, and you don't want to have to transport megatons of fissile materials all the way out to Saturn! (You think you have issues with the anti-nuke crowd *now*...)
-the other Doug
Oh, I understand -- uranium has a higher potential energy density than a lithium battery. I'm just thinking in terms of logistics. Any plan that requires bringing along enough fissile materials to support a manned base is going to be harder to accomplish (in terms of just getting everything to Titan and setting it up) than a plan that can actually draw enough power for its operations from indigenous sources.
Titan is just so energy-poor... you'd need to cover hundreds of square kilometers of landscape with solar cells to get anything useful at that distance from the Sun and through that thick haze. And you just can't extract heat out of a system that doesn't have any...
-the other Doug
Has anyone mentioned 'hydro'power? All you need is a lake on a hilltop - or one with tides. There could be 'geo'thermal possibilities too, and wind power.
Nigel nailed it! There are lots of really good energy sources on Titan:
Wind - wind speeds low but fairly steady, but atmosphere is thicker than on Earth. And dunes give a great indicator of funneling of winds from topographical features. (Double Bonus, we can use dune features visible NOW to select best places for wind farms!)
"Hydro" - If any of the polar streams are flowing at rates even close to those predicted by dimension, there's a massive potential for methane fluid flow.
Geothermal - Findind a fairly recent crater could allow you to trap residual heat from liquid water-ammonia. Also, there might be circulating fluids down deep (molten water-ammonia? molten organics?). Water has good heat capacity due to it's phase change energy. (It releases lots of heat on crystallization)
Chemical - There may be natural organic ore bodies that could be useful for energy production. For example (and I'm speaking off the top of my head - someone would need to look at the energies to see if it would be useful), a deposit of pyridinium N-oxides might be equivalent of a fuel deposit on Earth. (Pyridinium N-oxide could be used as an oxidant). There could be other potential reactant bodies lying around (or easily mined) that are prevented from reacting due to kinetic barriers from normal Titan conditions. Add a catalyst, or enough heat to overcome the barrier, and bingo, you've got an energy source. (Maybe not as impressive as fire, but any exothermic reaction helps!)
Finally, what are then energies involved in splitting water, taking the oxygen, then burning hydrocarbon? (This might be "carbon neutral" on Titan - since you are swapping one IR absorber for another)
What are the energies for:
H2O --> H2 + O2 [uphill]
O2 + CH4 --> CO2 + H2O [downhill]
H2 + C2H4 (or C2H4) + cat --> C2H6 [downhill]
Titan has oodles of potential energy sources. We've got evidence of wind (Huygens drift and dunes), evidence for permanently flowing liquids is tanalizingly close, and exploitable chemical and geothermal sources will require more research and examination. (So surface exploration serves two roles: science and energy prospecting).
-Mike
I assume this is all 500 years-from-now-Titan-colony type speculation. Any first visit or indeed, first 'round' of visits - I wouldn't rely on ANYTHING other than that which I could take with me.
Doug
'Tracking in' materials from outside might be complicated by some of the materials possibly formed outdoors not being particularly volatile below 0 C. Kerogen (or precursors) have been tenatively ID'd on asteroids, and might occur on Titan too. Polymerized Titanian 'gunk' might have to be carefully scrutinized by Huygen successors to assess the dangers. Additionally, our earthian environment is characterized by a polar solvent, water, and we are most skilled and experienced with that. Titan seems to have a 'hydrological' cycle driven by a non-polar fluid, and probe design will be challenging in regards to material properties and chemical effects.
What still concerns me about any operations on Titan (manned or unmanned) is the rather phenomenal temperature difference at which terrestrial machines and organisms (i.e., us) can operate versus Titan's natural environment.
Any terrestrial outpost or machinery is going to add *significant* amounts of heat to the Titanian environment. If ever there was a situation where observing a phenomenon affects that phenomenon, this is it.
We may have to figure out how to develop robots that can operate entirely at Titanian temperatures before we set out to study the place at close range, because the heat our current technology would be pumping into the local materials will change them in innumerable ways, and we won't see them as they've developed in situ.
-the other Doug
The cold is going to be THE big problem facing probes, machines, and colonists on Titan. Compared to other moons, Titan's atmosphere is thick, cold, and windy. So there will more heat conducted away from warm objects on Titan compared to other moons where objects will be partially be isolated by vacuum.
[Compare keeping hot coffee in a Thermos to trying to keep a hot cup of coffee in a pan of cold water.]
A heavy methane rain would also do a really great job of sucking heat away from warm stuff on the surface as well, both from conductivity from the moving fluid but also from the instant evaporation of the methane rain drops when it hits the warm surface. Just like the first raindrops from a summer thunderstorm disappear when they hit a warm sidewalk here on Earth.
But think of the fun the colonists will have shattering roses, driving nails with bananas, and other fun low-temperature experiments.
-Mike
Odd how the analogies between Venus & Titan keep cropping up, even though sometimes 180 deg out of phase from one another. Dewar-type vessels have also been proposed for Venusian probes.
Some of the surface materials may DETONATE on being warmed.
Take (I think) cryogenic nitrogen and methane ices mixed, irradiate with charged particles.... it turns yellow, and DETONATES on being warmed toward sublimation temperatures.
Good grief... !!! Are you saying that there may be natural minefields on Titan? Do these compounds have an affinity for each other, or do they tend to disperse? (By that I mean in the "wild" state instead of under laboratory conditions, if the possible circumstances for natural formation are at all understood; assuming it doesn't happen naturally on Earth.)
"Do you have a reference for this? I poked around a little and couldn't find anything...."
This was being presented back in the late 80's at Lunar and Planetary Science Conferrences, post Voyager-2 at Triton. Results may/probably-are also in DPS and AGU Spring/Fall meeting abstracts.
re: "Wile E. Coyote Memorial Station"
ROTFLMAO.
...thank you, Ed, but all credit to Shaka for that mental image!
Damn interesting, though. We've been thinking of organics as essentially inert, but quite obviously they're not else life on Earth wouldn't have happened in the first place. Titan's chemosynthetic history & capabilities are unknown, and it will probably take several generations of surface probes to shed enough light to enable manned exploration...
Re: stuff blowing up on Titan
Well, assuming for the moment that we're not likely to hop across the surface from multiple "land-mine" encounters, how would a large manned vehicle (LM-class or better) execute EDL? Seems easier at first glance than landing on Mars because of the thicker atmosphere & lower gravity (and lower initial orbital velocity to shed).
Side note- "If you're not part of the solution, you're part of the precipitate"...comedian Steven Wright, no? That guy is absolutely brilliant.
How effectively, given current materials technology, can we insulate the "ground" where we would locate a Titanian habitat from the heat within the hab?
Seems to me we're going to have to limit heat leakage from the hab *very* selectively, or else the "ground" (or at least some of it) will become liquid where in direct contact... thereby alleviating your worries, Nick. No matter what we do, she'll eventually end up afloat, regardless!
-the other Doug
Ahrrr...har, har, har, David! Yeah, I'm thinkin' that playing mast monkey in a spacesuit even at 0.25G might not be the safest way to go...(although I hear the Navy guys from another thread cheering in the background)...
oDoug, that's a scary thought. Only thing that could be done is, assuming that the habitat/lander is basically a Dewar flask, limiting the internal vessel physical interfaces to & beyond the outer shell so that heat conduction is controllable: I'd use some thick, heavily insulated copper cabling (unless an advanced superconductor is available 200 years from now when all this might happen) attached near each interface point about 100m long, and stick the business end into the "soil" that far out...let it melt over there, not near the habitat. Notice also that this most effectively provides electrical grounding for the lander.
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