Manned Landing On Titan, Issues & Answers? Options

[JonClarke]

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 drop in 0.7 bar is not enough to result in the bends when people don in Shuttle EMU. So I don't see why a 0.6 bar drop should be an issue. If it is a concern, the ascent vehcile would require many hours to ascent to orbit and dock to the other ship, during which time the pressure could be gradually lowered. Breathing an atmsophere with a higher partial pressure O2 durting ascent would also speed N2 outgassing, if required.

As for the airlock, what is the rate at which methane and other noxious gases can be removed from the atmosphere, and how is it removed?


Jon

[nprev]

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?

[JonClarke]

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.

I have done some reading on particulate removal, which can be very fast and efficient, but don't know much about organic gases, which is why I asked. It would be interesting to find out how much pressure differential is required. Labs and factories that use hazardous materials run an\t lower pressures than the outside world, warships and some military vehicles operating under NBC conditions have higher internal presures to keep nasties in and out respectivively, this could serve as a guide for what would be required on Titan.

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! )

RTGs probably don't deliver enough power for a crewed mission. Failing compact fusion I think a fission reactor is the best option, at least initially. The high atmospheric density makes it easier to dispose of waste heat from a reactor on Titan than on the Moon or Mars, rather than relying on passive radiators (remember for every kW of electricity a reactor typically generates about 10 kW of waste heat), cooling fans would greatly increase the effectiveness of convection in dumping heat. Heat pads or rods into the ground would be another option, but you would not want to over do it.

For a permanant station, a wind farm might be an attractive supplement, given the low gravity, high atmospheric density, and presence of locally strong winds (there are lots of dunes on Titan). Titan has an internal heat source so geothermal (titanothermal?) power is another alternative.

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?

Well the rocks appear to be water ice and ice clathrates, so with the waste heat you could melt the ice and electrolyse the water to oxygen. Methane and hydrogen could be recovered if needed, or simply dumped. The amount of methane in the Titanian atmosphere will support combusition with the addition of sufficient oxygen. So you could simply run reverse combustion engine, drawing ambient atmosphere into a combustion chamber, injecting oxygen, and igniting the mixture for example with a diesel engine or gas turbine. This makes long range ground vehicles and aircraft a much easier proposition than on Mars, for example. Methane and oxygen would be an ideal propellant combination for ascent and descent vehicles, although again, with sufficient plant and abundant atmospheric nitrogen, methane and a source of oxygen you could also manufacture storable hypergolics like hydrazine and nitrogen tetroxide, if you needed to.

Jon

[RNeuhaus]

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

[ugordan]

Easily. They will not talk. They will send messages.

[nprev]

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.

[nprev]

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.

[djellison]

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

[Juramike]

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?

Actually, this is a pretty easy.

The bulk of Titan's atmosphere is nitrogen. It would be straightforward to set up a condensation/refining unit that could make and store pure liquid nitrogen directly from the atmosphere. (Heck, you are almost at the liquid temperature anyway). That would give you a useful supply of nitrogen for flushing and for atmosphere reconstitution.

Once inside the airlock, a flush of warm (298 K) nitrogen will bring everything up to "normal" temperature, and volatilize most of the organics. A few evacuation/purge cycles with nitrogen should flush out most of the volatile yukkies. Then a simple scrub down of the suits with common decontamination solvents (fancy soaps and detergents) (at this point you could also use water), a last evac/purge cycle with fresh nitrogen, and you should be good.

The evacuation procedures could be replaced with extensive nitrogen atmosphere changes or multiple airlocks, or simple door chambers, each with a higher positive pressure to maintain atmospheric integrity.

Future colonists would have to live at a slightly elevated pressure inside their living environment (slightly above 1.5 Atm) to ensure that any breaches have a positive pressure going from "good" environment to "contaminated" enviroment. (Most GMP labs maintain their environment by having a slight positive pressure). [On Earth's surface, the pressure goes up 1 atmosphere for every 33 feet of water on Earth, so simply snorkeling gets you exposed to Titan's pressure!]

Inside the living environment, organic contaminants can be filtered from the atmosphere using a wide variety of filters that have been developed. Go to any hardware store and you can see NIOSH filters that will remove acidic, basic, or neutral volatile organics for respirators. Activated charcoal is the best for removing most volatile organic compounds (VOC's). There are also commercial analyzers that can be used to monitor the atmosphere for buildup of any organics.

The only energy intensive part will be keeping and maintaining the oxygen part of the atmosphere. That will have to be recycled and/or generated from electrolysis of water ice.

All of the precautions used for high VOC environments on Earth (e.g. paint sheds), could be easily incorporated for future living spaces on Titan. The harder problem will be insulating from the extreme cold.

-Mike

[nprev]

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...

[Reckless]

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

[nprev]

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.

[ngunn]

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!!!

[nprev]

Ah. Then we need to just ground the hell out of the place....

[Reckless]

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