Life support (ECLSS), water and atmosphere

Key results

• Consumables. NASA allocates ~5 kg per person per day, mostly water, which is 1.85 t per person per year Roy_H, 2014-02-16; KelvinZero, 2015-03-10.
• How gravity helps ECLSS.
• Paul451 asked how little g would simplify cooling, water recycling, toilets and ventilation; ISS operations cost ~$3B/yr Paul451, 2015-02-20.
• Even 0.1 g eases bathroom use, eating, cooking and washing TrevorMonty, 2018-07-16. Convection helps mikelepage, 2019-05-03.
• Long-term workers need beds, showers and toilets, so a spin habitat is eventually necessary llanitedave, 2014-02-23.
• Convertible 1 g/0 g showers, laundry and toilets (H-10-K) Darren_Hensley, 2016-01-08.
• Caution. ECLSS and thermal components optimized for 0 g may misbehave in spin gravity, so existing modules might give misleading results; mikelepage suggests a clean-slate satellite mikelepage, 2015-11-09.
• ISS practice. O₂ comes from electrolysis with the H₂ vented; CO₂ is removed and dumped; Sabatier has been tested lamontagne, 2019-10-26. ISS arrays are mostly for electrolysis lamontagne, 2023-01-26.
• Scaling to settlements (lamontagne): 10,000 people produce 11,000 kg of CO₂ a day, giving 4000 kg of methane via Sabatier. That needs ≥10–12 MW; lights and fans are ~48 MW lamontagne, 2022-10-07.
• Bioregenerative options.
• Algae bioreactors at >0.9 g CO₂/L/day need ~1.1 m³ of reactor per person mikelepage, 2023-03-09.
• ESA MELiSSA; lamontagne proposes triple redundancy: a chemical backup, MELiSSA, and food production lamontagne, 2023-03-13.
• Consider one bioregenerative section Coastal Ron, 2023-09-13. Dedicated external recycling modules Coastal Ron, 2023-03-13.
• Freeze out VOCs, CO₂ and water, and recycle solvents for industry Paul451, 2023-05-27.
• mikelepage's "SCWorM" module (Septics, Compost, Worms, Maggots) feeds algae and aquaponics mikelepage, 2023-01-30.
• Food waste can become methane propellant stefan r, 2023-10-17.
• Biosphere 2: its concrete absorbed O₂ and CO₂, unbalancing the atmosphere JohnFornaro, 2023-03-11. Its failures were predicted by critics Paul451, 2023-03-10.
• Self-sufficiency scope.
• Early stations should aim at near self-sufficiency for O₂/CO₂ and water, and import food mikelepage, 2023-03-11.
• Near-term stations can be testbeds for food production and life support while relying on Earth supply lamontagne, 2023-03-06. "No station ever self-sufficient" Coastal Ron, 2023-03-06.
• With Starship's 200 t resupply, a closed loop is not required LMT, 2023-09-14.
• Water.
• Water is preferred over oil for balance tanks: it serves life support, shielding, electrolysis and O₂ storage, has no chemical hazard, and is heavier Coastal Ron, 2018-08-05; lamontagne, 2018-08-05.
• Water in a co-rotating ring has no net flow unless there is vertical convection; then Coriolis makes vortices Paul451, 2015-03-24. It can be used for coolant or aquaponics circulation mikelepage, 2015-03-25.
• Shielding water needs clean/dirty tank balance Coastal Ron, 2023-05-24.
• Leakage.
• The ISS loses ~300 g/day Paul451, 2024-01-28. EVAs and docking cycles are the main losses LMT, 2024-02-06. Pumped double gaskets give ~500× reduction Twark_Main, 2024-02-14.
• Details are in seals.
• Toilet capacity for hundreds of people in a transit shuttle lamontagne, 2022-10-24. The Bill Gates waterless toilet was suggested for small stations lamontagne, 2019-04-12.
• Multiple atmospheres. JohnFornaro's three atmospheres: Earth ring, Mars ring, hub/spokes JohnFornaro, 2023-01-24.
• Utilities space. Expect ≥20% of station volume for utilities Twark_Main, 2024-08-15.

Open questions

• Which ECLSS subsystems need redesign for 0.3–1 g, and which work better?
• Where is the break-even for closing the loop in LEO with cheap Starship resupply?

Related pages

• Agriculture and food · Fire safety · Power · Research and testbeds

Sources

Forum posts

• Roy_H, 2014-02-16 (reply #2): ~5 kg/person/day. Post. Attachments: SpaceStationDark_small.jpg, CafiteriaModuleCutaway_small.jpg, CafeteriaInterior_small.jpg, SpaceStation.pdf.
• llanitedave, 2014-02-23 (reply #119, 5 likes): Workers need showers/toilets (5 likes). Post.
• Paul451, 2015-02-20 (reply #300, 1 like): How little g simplifies ECLSS. Post.
• KelvinZero, 2015-03-10 (reply #496): ~1 t per 200 days. Post.
• Paul451, 2015-03-24 (reply #541, 1 like): Water ring convection. Post.
• mikelepage, 2015-03-25 (reply #543): Coolant/aquaponics circulation. Post.
• mikelepage, 2015-11-09 (reply #742, 3 likes): 0g-optimized ECLSS may misbehave (3 likes). Post.
• Darren_Hensley, 2016-01-08 (reply #785): Convertible facilities. Post.
• TrevorMonty, 2018-07-16 (reply #948): 0.1 g eases bathroom/cooking. Post.
• Coastal Ron, 2018-08-05 (reply #1157): Water better than oil. Post.
• lamontagne, 2018-08-05 (reply #1162, 1 like): Water better. Post.
• lamontagne, 2019-04-12 (reply #1540, 1 like): Waterless toilet. Post.
• mikelepage, 2019-05-03 (reply #1583, 1 like): Convection helps ECLSS. Post.
• lamontagne, 2019-10-26 (reply #1695, 2 likes): ISS ECLSS practice. Post. Attachments: Worldship designer (5).xlsx, Propellant production (10).png, Colony life systems.png, Colony power systems (1).png.
• lamontagne, 2022-10-07 (reply #1912, 1 like): CO₂ processing 10–12 MW. Post. Attachments: radiator.xlsx.
• lamontagne, 2022-10-24 (reply #2197): Toilet capacity. Post.
• JohnFornaro, 2023-01-24 (reply #3055): Three atmospheres. Post. Attachments: Wobble-Water-System-A.JPG.
• lamontagne, 2023-01-26 (reply #3117): Arrays for electrolysis. Post.
• mikelepage, 2023-01-30 (reply #3191): SCWorM module. Post.
• lamontagne, 2023-03-06 (reply #3514, 1 like): Testbeds relying on Earth. Post.
• Coastal Ron, 2023-03-06 (reply #3516, 1 like): No station self-sufficient. Post.
• mikelepage, 2023-03-09 (reply #3538): Algae bioreactor sizing. Post.
• Paul451, 2023-03-10 (reply #3545): B2 failures predicted. Post.
• mikelepage, 2023-03-11 (reply #3549, 2 likes): Aim at O₂/CO₂/water; import food (2 likes). Post.
• JohnFornaro, 2023-03-11 (reply #3552): B2 concrete absorbed O₂. Post.
• lamontagne, 2023-03-13 (reply #3563, 2 likes): MELiSSA + triple redundancy (2 likes). Post.
• Coastal Ron, 2023-03-13 (reply #3564): External recycling modules. Post.
• Coastal Ron, 2023-05-24 (reply #3744): Clean/dirty balance. Post.
• Paul451, 2023-05-27 (reply #3758, 2 likes): Freeze-out separation (2 likes). Post.
• Coastal Ron, 2023-09-13 (reply #3928): Bioregenerative section. Post.
• LMT, 2023-09-14 (reply #3931): Closed loop not required. Post.
• stefan r, 2023-10-17 (reply #4185): Food waste → methane. Post.
• Paul451, 2024-01-28 (reply #4428): ISS 300 g/day. Post.
• LMT, 2024-02-06 (reply #4455): Schaezler 2011. Post. Attachments: Schaezler et al. 2011 Table 1.png.
• Twark_Main, 2024-02-14 (reply #4475): Double gasket. Post.
• Twark_Main, 2024-08-15 (reply #4740): ≥20% utilities. Post.

External references

• ESA MELiSSA programme.
• BIS, JBIS 73(6), June 2020 (Avalon life support).
• marspedia.org Life_support and Sabatier pages.