Extending Life Support

[JustinInOz]

Life support is puzzling me.

In CT it costs 2000 cr per 4 weeks. Ok fine here. Those martinis with the green olives don't come cheap for the high passage travellers. Is the high price some sort of market collousion? Given the free market that traveller is portrayed to be, I would imagine that some enterprising soul would have broken ranks in the 1100+ years of the 3rd Imperium. I guess when you are paying to breath in space, you are willing to dig deep.

What is involved if the travellers have demountable tanks and they want to make two jumps? The mid point is in the middle of deep space. No facilities there. When they get there the place will have no facilites. They will be able to refuel at a gas giant. They then make the two jumps to get back.

All round this is a 4 week trip + time to check drives before jumping again + time at the destination + time skimming.

They are going to need more "life support". Let's say that they want to have 12 weeks life support.

How much space does this take up in the cargo hold? Can "forraging" acount for some of this at the destination? I imagine that the standard 4 weeks of life support takes up its space in the allocation of the stateroom. More than this has to be storred in the cargo hold.

Just what, physically, is life support? Filters and catalysts? Food of course. But what else? Traveller ships have no problem splitting water into hydrogen and oxygen to fuel power plants. So they should have no problem breaking CO2 into O2. At a bit of a stretch they could take H2O and CO2 and turn them into O2 and Carbohydrates. I am probable wandering into arrant speculation at this point.

Back to my main question, how much space does it take up? Why does it cost so much?

 

[aramis]

ISTR 50 person-weeks per ton displacement as cargo, at KCr2500 per ton

 

[JustinInOz]

That means

Calculating that out puts 1 person week at 50 KCr.

Are you sure? 50,000 Cr for 1 week?

if 1 dton is 13.5 kl then 1 week comes in at 270 litres. I am fine with that figure.

The cost seems a bit out of whack though.

Thanks for the quick response.

 

[Drakon]

What is life support?

Life support is puzzling me.

Just what, physically, is life support? Filters and catalysts? Food of course. But what else? Traveller ships have no problem splitting water into hydrogen and oxygen to fuel power plants. So they should have no problem breaking CO2 into O2. At a bit of a stretch they could take H2O and CO2 and turn them into O2 and Carbohydrates. I am probable wandering into arrant speculation at this point.

I cannot address cost or volumn, but I think I can address this one.

Life support includes 1a) Air, primarily O2 supply. This can be done either via splitting O2 out of water, (If water is available.) or by some form of tankage. Either physical bottles of O2, or pyrotechnics like O2 candles. O2 is the one thing we are concerned with, because that is what gets used up in breathing. N2 and/or any other non-threatening nor explosive gas is not a problem. Those just get recycled.

1b) Humans do produce CO2, which can be deadly at high enough consentrations. This has to be removed. Any other poisonous or explosive gasses also need to be gotten rid of. And these waste gasses or products of waste gasses have to be expelled or stored. On submarines this is done through CO2 scrubbers, and burners. The CO2 scrubbers run air through a sprayed liquid, (I can't remember what it is at the moment). The liquid sucks the CO2 out of the air, traps it in the liquid until the liquid is heated. When heated, its released in a controlled fashion, into a gas tank or pumped overboard. Its pretty much closed loop, and while pumps and mechanicals need maintenence, the liquid does not need to be replenished.

Burner run air through a baffle of heated metal catalyst. The catalyst causes things like H2 to burn, combine with O2, and turns into water which is recoverable. It also will burn any hydrocarbons in the air, turning them into CO2 and H2O. Catalyst does not get used up and good for years. It just makes reactions more likely, rather than become part of the reaction. The mechanicals will need maintence.

1c) Ventilation: You need to move the air around and this will require fans, ventilation ducting and such. You will probably want electrostatic precipitators and filters to keep any dust from spreading around the ship. And a means of isolation in case something bad happens. Filters may or may not be of a "clean and reuse" nature, but electrostatic precipitators are essentially little more than parallel metal plates with a high voltage charge on them. and thus washable. Fans, being rotating machinery, need maintence.

1d) Temperature and pressure. While high pressure is not a big problem normally, when you want to go to lower pressures, you will have to decompress. You will need some way of regulating pressure inside the ship, as well as heating and cooling. Which means air conditioning, heaters, and an air compressor with tanks. (With the hipack, if the pressure gets too high, pump some air into the tank. If pressure gets too low, bleed air from the tanks.) Lots of mechanical stuff here.

2a) Water: Evaporators to purify water. Will need multiple tanks, one for the purified water, one for the "raw" or dirty water. And those tanks will need to be cleaned out, or flushed from time to time. And again, the mechanical aspects of maintence. YOu can use de-ionizers for very high purity water, but this requires a resin that wil have to be changed out frequently, (depending on how dirty the water is you run through it)

3a) Food: Not only storage, but safe preparation of it. Microwave ovens and such do not require constant maintence, nor do refrigeration units. But this is one of the hardest to "close loop". And this may be where the bulk of the cost comes in, groceries.

2-3b) When you eat or drink, it has to go somewhere eventually, so life support also includes things like freshers and heads. Showers will produce waste water, as will heads, which can be cycled back through the water purifiers. Obviously, you will want some sort of "pre-processing" before you dump it into drinking water tanks. On board submarines, we would just pump the sewage overboard, once we were far enough from land. This might not be a good idea in high traffic spaceways. (or even low traffic ones for that matter. Delta V is the killer.)

4) Sensors and control. You will need to monitor air and water quality, and either kick in burners, bleed O2, or control the machinery to improve the quality. While automated is great, I would recommend manual bypasses for control equipment. You don't want a computer crash to prevent you from getting breathable air.

It does appear to me that the cost should be rated against the "closed looped" ness (efficiency?) of the various subcomponents. If your water is 100% closed loop, if you process and are able to recover all that is used, then that should eliminate any costs associated with obtaining water. Same for air, although this is harder. Food, harder still. But savings in one component should help reduced costs for life support in total.

 

[aramis]

Calculating that out puts 1 person week at 50 KCr.

Are you sure? 50,000 Cr for 1 week?

if 1 dton is 13.5 kl then 1 week comes in at 270 litres. I am fine with that figure.

The cost seems a bit out of whack though.

Thanks for the quick response.

Sorry, should have been KCr25 or Cr25000, but if one buys in bulk, one should reasonably cut that to KCr20 per 50 weeks. (20% off).

It was in Best of JTAS #1, Asteroid mining article.

 

[BlackBat242]

Salary for the required Steward (1 per 8 high passengers).

Periodic refurbishment of passenger quarters (unless you like that "shabby chic" look).

Increased premiums for required insurance for passenger-carrying vs cargo-only.


Shall we continue?

 

[aramis]

Black Bat:

Salary is not included in the LS costs, as the salary for the steward is a separate entry in all the design/operations rulesets...

Lets see, at a nominal 3 meals per day, 4 weeks per month, that's 28*3=84 meals. Meals alone are 600 Cr of that 2000 (CT - TTB, p 109, "High Living") or about Cr 7.5 per meal.... let's call that a L apiece.
So we've 1400 left to account for.

Lets see. 6 hours oxygen is Cr20 (TTB 107 - Oxygen Tanks). so each day is Cr80 in O2, but we'll cut a generous discount of 50% for a rebreather/scrubber system. So 40*28=1120, and that's going to be in UHP tanks....

Which leaves Cr80 for 4 CO2 scrubbers, at about a L each...
but those probably are not that expensive. Call it Cr40?

the remaing Cr40 is probably lubricants, surfactants, and disinfectants. For rooms and clothing. Call that another 5L...

Oh, and TTB, on page 67, sets the Dton to 14m³, and implies useful space is 13.5m³.

 

[Icosahedron]

I have the filters changed, food bought, heads emptied, tanks cleaned, etc as part of the berthing process. Whether it is paid for in the berthing fee or the life support cost is irrelevant, but what happens when you land at a class E or X??

 

[atpollard]

I have the filters changed, food bought, heads emptied, tanks cleaned, etc as part of the berthing process. Whether it is paid for in the berthing fee or the life support cost is irrelevant, but what happens when you land at a class E or X??

Then the whole crew scrubs or the ship starts to smell like an old scout ship.

 

[BlackBat242]

OK, I thought part of his question was justification for the cost of high passage as it relates to things like life support.

I really shouldn't try to read & post when I'm having problems focussing my eyes due to fatigue.

 

[Maccat]

IMTU Life Support

I've seen the 50 person-week thing, yet prior to that i had worked up from LBB2 using O2 tankage for the vacc suits, and rations therein, worked out to: 4k for 1 person 4 weeks at 1.5t
.6t 02
.35t H20 @ 7gal/d, 705 credits
.55t mix half fresh, half canned rations

makes it a real challenge to design long range journey then!

 

[aramis]

You're forgeting something important, Maccat:
Bigger tankage holds more as a portion of its volume than a smaller tank of the same pressure; further, one can easily make the tank higher pressure since the volume will be less adversely affected.

So, that 50/ton , you can pack the O2 as liquid crygenics at considerably more than as a high pressure gas. You can reliably package bulk foods more tightly than individual meals, even if the servings are individual; you can regularize the space more.