Living on Mars Is a Recycling Problem

Water recycling in orbit reached 98%. Oxygen can be pulled from the Martian air. Food still comes entirely from Earth. The frontier has moved from recycling machinery to growing crops, and growing crops is a power problem.

Last updated September 2026

Figure 1

Water closed. Air half-closed. Food never left Earth.

How much of a crew’s daily water, oxygen, and food is regenerated rather than resupplied, in flight and in sealed habitats on the ground.

Flight status · 2026

<1% · No crewed spacecraft has grown a meaningful share of its crew's calories.

Figure 1: Flight series are Measured: water recovery as reported by NASA for the ISS, and oxygen as the share recoverable from exhaled CO₂ by the ISS Sabatier reactor, which does not run continuously. Ground series show the share of food grown inside sealed habitats; the Lunar Palace 365 value is reported, while the BIOS-3 and Biosphere 2 values are approximate and are shown to indicate magnitude only. Ground habitats had Earth gravity, Earth power, and help nearby, so they are not flight results. Select any point for its source.

98%Water recovered on the ISS from 2023, up from 93-94% before the brine processor and from zero on Apollo.

122 gTotal oxygen MOXIE made from Martian air in 16 runs, peaking at 12 g an hour: proof of process, a hundredfold short of crew scale.

~0%Share of calories grown in flight. The best sealed ground habitat grew 73% of its food mass for a year.

What the record shows

Physico-chemical recycling has nearly finished the job it can do: 98% water recovery in orbit, and about half the oxygen in exhaled CO₂.
Mars changes oxygen from a recycling problem into a manufacturing problem. MOXIE showed the chemistry works on the surface; the gap to crew scale is about 100× in throughput and years in lifetime.
Once water and oxygen are closed or made locally, food is about four-fifths of what a Mars crew must still bring. The binding constraint has moved from recycling to agriculture.
Agriculture on Mars is a power and reliability problem: kilowatts of light per person, no resupply for 26 months, and a biological system that must not drift.

This report is about keeping people alive and fed inside habitats on Mars. It does not treat terraforming the planet as a near-term engineering programme; the reasons are set out below.

Figure 2: The six loops

A settlement is six loops that must all close at once

Water is nearly closed. Oxygen can be manufactured from the Martian air. Food, nutrients, shielding, and power are where the mass and the uncertainty now sit.

The largest share of consumable mass once water and oxygen are closed.

Daily need: About 1.8 kg a person a day as packaged food, around 2,500-3,000 kcal
State of the art: Carried from Earth. Flight crops are supplements; the best ground habitat grew 73% of food mass
What Mars offers: Sunlight is about 43% of Earth's at the top of the atmosphere and weakened further by dust; crops need pressurised, warmed, lit volume
Evidence: Measured on the ground, not in flight

Binding constraint: Photons. Growing a diet takes kilowatts of light per person and tens of square metres of growing area, plus crop failure risk that stored food does not have.

Daily needs are rounded from NASA baseline values for an average crew member. Dose figures are from the Radiation Assessment Detector on Curiosity. Loops interact: crops recycle CO₂ and water, and waste processing feeds crops, so closing one changes the load on the others.

Part I: First principles

A settlement is a mass balance with a 26-month delivery schedule

Whatever the crew consumes and does not regenerate or make locally must be launched from Earth, landed, and stored until the next window.

Mass from Earth≈crew × days × daily need×(1 − share regenerated or made locally)+hardware, spares, and power

Closing a loop trades consumable mass for hardware mass and power. On the ISS, where cargo arrives every few months, that trade is about cost. On Mars it is about survival: the loop must keep closing for two years with only what was brought.

01

Get there

Transport sets the price of every kilogram the settlement does not make for itself, and the calendar: Earth and Mars line up for a launch about every 26 months.

Measure: Cost per kilogram landed, landed mass per window, transit time
Failure boundary: A cheap ride to orbit that does not become a cheap, reliable landing on Mars

What the record shows at this step

Reported evidence: No payload heavier than about a tonne has landed on Mars; Perseverance, the heaviest, was about 1 tonne.
Where it is moving: Fully reusable heavy transport refuelled in orbit, landing tens of tonnes per ship (Target).
Principal risk: A cheap ride to orbit that does not become a cheap, reliable landing on Mars

Evidence statements describe missions, experiments, and published results. “Where it is moving” is an editorial reading of direction, not an announced capability.

02

Shelter

A pressurised volume at room temperature, on a planet with an atmosphere under 1% of Earth's pressure, an average near −60 °C, and no magnetic field.

Measure: Habitable volume per landed tonne, dose per day inside, leak rate
Failure boundary: Leaks, thermal cycling, and radiation dose that accumulate over a long stay

What the record shows at this step

Reported evidence: Curiosity measured about 0.7 mSv a day on the surface and about 1.8 mSv a day during cruise.
Where it is moving: Habitats covered with regolith or water, and construction printed from local material.
Principal risk: Leaks, thermal cycling, and radiation dose that accumulate over a long stay

Evidence statements describe missions, experiments, and published results. “Where it is moving” is an editorial reading of direction, not an announced capability.

03

Power

Every other loop draws on it. Oxygen, heat, water processing, and above all lit crops turn into kilowatts per person.

Measure: Continuous kilowatts delivered, mass per kilowatt, output through a dust storm
Failure boundary: A weeks-long dust storm that halves solar output while crops and heaters still need power

What the record shows at this step

Reported evidence: A 2018 NASA test reactor produced 1 kW of electricity; a 40 kW lunar fission system is a target.
Where it is moving: Surface fission reactors, with solar and storage as supplements.
Principal risk: A weeks-long dust storm that halves solar output while crops and heaters still need power

Evidence statements describe missions, experiments, and published results. “Where it is moving” is an editorial reading of direction, not an announced capability.

04

Air

Oxygen for breathing, CO₂ removal, and trace-contaminant control. On Mars, oxygen can come from the atmosphere rather than being recycled.

Measure: Oxygen per day, energy per kilogram, hours between failures
Failure boundary: A system that works in short runs but degrades over thousands of hours

What the record shows at this step

Reported evidence: MOXIE made 122 g of oxygen in 16 runs on Mars (2021-2023), at up to 12 g an hour and 98% purity.
Where it is moving: Solid-oxide electrolysis scaled roughly a hundredfold for crews and return propellant.
Principal risk: A system that works in short runs but degrades over thousands of hours

Evidence statements describe missions, experiments, and published results. “Where it is moving” is an editorial reading of direction, not an announced capability.

05

Water

Drinking, food preparation, hygiene, and, if crops are grown, many times more for irrigation and transpiration.

Measure: Recovery rate, spares per year, ice extracted per day
Failure boundary: Microbial growth and hardware wear with no replacement parts closer than 26 months

What the record shows at this step

Reported evidence: The ISS recovered 98% of its water in 2023, after the brine processor was added.
Where it is moving: Ice mining at mid-latitude sites, which turns recycling losses into a mining problem.
Principal risk: Microbial growth and hardware wear with no replacement parts closer than 26 months

Evidence statements describe missions, experiments, and published results. “Where it is moving” is an editorial reading of direction, not an announced capability.

06

Food

The largest remaining consumable once air and water are closed. Growing it requires light, pressurised volume, nutrients, pollination, and a buffer against crop failure.

Measure: Share of calories grown, growing area and power per person, harvest reliability
Failure boundary: A failed harvest with no resupply for two years

What the record shows at this step

Reported evidence: Flight crops are supplements. On the ground, Lunar Palace 365 grew 73% of its food dry mass inside the habitat for a year.
Where it is moving: High-yield dwarf crops, algae and insects for protein, and greenhouses lit partly by sunlight.
Principal risk: A failed harvest with no resupply for two years

Evidence statements describe missions, experiments, and published results. “Where it is moving” is an editorial reading of direction, not an announced capability.

07

Nutrients and microbes

Waste must become fertiliser, and the microbiome of crew, crops, and habitat must stay stable. This is where a greenhouse becomes an ecosystem.

Measure: Nitrogen recovered, solid waste processed, pathogen and contaminant levels
Failure boundary: Slow, invisible drift: soil respiration, gas imbalances, or microbial blooms

What the record shows at this step

Reported evidence: Lunar Palace 365 recovered about 67% of solid waste. Biosphere 2 lost oxygen to soil microbes and concrete.
Where it is moving: Compartmentalised microbial reactors, as in ESA's MELiSSA, that keep each process controllable.
Principal risk: Slow, invisible drift: soil respiration, gas imbalances, or microbial blooms

Evidence statements describe missions, experiments, and published results. “Where it is moving” is an editorial reading of direction, not an announced capability.

Figure 3 · Interactive model

What a Mars crew must bring from Earth

A conjunction-class Mars mission lasts about 900 days: roughly six months each way and more than a year on the surface waiting for the planets to realign. There is no resupply in between. Every kilogram not regenerated or made locally must be launched, landed, and stored.

Crew4Mission length900 daysWater recovered or mined98%Oxygen recovered or made locally50%Food grown0%

ISS-class recycling8.2tonnes of consumables

63% less than a fully open loop (22 t)

Food: 6.5 t · 79%
Water: 0.3 t · 3%
Oxygen: 1.5 t · 18%
Person-days: 3,600

Step through the scenarios. ISS-class recycling cuts the bill by nearly two-thirds, and once water and oxygen come from Mars, food is essentially all that remains. That is why the frontier has moved from recycling machinery to growing crops, and why growing crops turns into a power problem.

Calculation & assumptions

Consumables = crew × days × (0.84 kg oxygen × unrecovered share + 3.5 kg water × unrecovered share + 1.8 kg packaged food × share not grown). Daily needs are rounded from NASA baseline values; hygiene water, spares, clothing, and propellant are excluded.

The model counts consumables only. Recycling, oxygen production, ice mining, and crop systems all have hardware mass, spares, and power that are not shown, so the real saving is smaller, and it grows with mission length: the longer the stay, the more a closed loop pays back its hardware.

Figure 3: Illustrative. Consumable rates are Derived from NASA baseline values; scenario closure levels are chosen to match the ISS record (Measured), MOXIE-class production scaled up (Projected), and a partial greenhouse (Projected).

The ISS proves that people can live for decades inside a machine. It does not prove they can live inside one that nobody can resupply.

How the bottleneck moved

Life support progressed in the order of mass saved per engineering effort: water first, then oxygen. What remains is the hardest part of the loop, because it is alive.

Water closed first

Water is chemically simple to purify and heavy to carry, so it repaid engineering first. Recovery went from zero on Apollo to 98% on the ISS.

Mars makes oxygen a supply problem

The atmosphere is 95% CO₂. Splitting it needs power, not recycling, so oxygen stops depending on how perfectly the loop closes.

Food is what is left

With water and oxygen closed or produced locally, about four-fifths of what a crew must bring is food. No spacecraft has grown a meaningful share of its crew's calories.

Food is a photon problem

Plants turn a few percent of light into edible energy. Growing half a diet for four people with electric light needs tens of kilowatts, more than any power system yet flown to another planet.

Figure 4 · The power floor

Growing food costs far more power than making air

Splitting CO₂ for oxygen has a hard thermodynamic floor of about 5 kWh per kilogram, and even MOXIE-class hardware sits within a factor of ten of it. Food has no such shortcut: plants turn only a few percent of light into edible energy, so a lit greenhouse costs kilowatts per person.

Crop lighting

22 kW50% of 2,800 kcal a day per person, 2.5% of light becomes edible food energy, 50% of electricity becomes light

Oxygen from CO₂

4.2 kW30 kWh per kg; the thermodynamic floor is about 4.96 kWh per kg (0.69 kW for this crew)

Reference: planned fission unit

40 kWNASA target for a lunar surface fission power system (Target)

Crew4Share of calories grown50%Light to edible energy2.5%Electricity to light50%Energy per kg of oxygen30 kWh

Continuous electric power26kW

84% of it for lighting crops

Per crew member: 6.5 kW
Food energy grown: 271 W
Oxygen made: 3.4 kg/day
Oxygen at the floor: 0.69 kW

Sunlight can replace some lamps, but Martian surface light is weaker than Earth’s, arrives through a pressure shell, and can be cut for weeks by dust storms. A settlement that depends on crops must either oversize its power plant or keep a stored-food reserve large enough to ride out a failed harvest.

Figure 4: Illustrative model with plausible magnitudes. The oxygen floor is Derived from the enthalpy of splitting CO₂ (about 283 kJ per mole of CO, 566 kJ per mole of O₂). MOXIE drew roughly 300 W while producing 6-12 g an hour, about 25-50 kWh per kg including compression and heating (Derived). Crop conversion efficiency depends heavily on species, light level, and how much of the plant is edible; 1-4% of delivered light ending up as edible energy is a common range for well-run controlled-environment crops. Heating, water processing, and habitat systems add further load not shown.

The floors are known. The gaps are engineering.

~5 kWh/kgThermodynamic minimum to split CO₂ into oxygen. MOXIE-class hardware used roughly 25-50 kWh per kg including compression and heat: within about a factor of ten.

1-4%Typical share of delivered light that controlled-environment crops turn into edible energy. The photosynthetic ceiling is higher, but food plants waste most of their biomass on stems and roots.

~0.7 mSv/dayRadiation dose measured on the Martian surface by Curiosity, against about 1.8 mSv a day in cruise and a 600 mSv career limit.

Oxygen is near its floor in principle and short of it in practice by a manageable factor. Food is far from any floor that matters, because the conversion from electricity to edible calories is set by crop biology. The runway there is in crop breeding, lighting, and using sunlight directly, not in better pumps.

The discovery chain

Two traditions developed in parallel: machines that recycle in orbit, and sealed biological habitats on the ground. A Mars settlement needs both to meet.

1968-1972
Open loop
Apollo carried its oxygen, food, and CO₂ absorbent, and took its water from the fuel cells. Nothing was regenerated.
1972-1973
The first sealed ecosystems
BIOS-3 in Krasnoyarsk kept three-person crews for up to 180 days on algae- and crop-regenerated air, with part of the diet grown inside.
1991-1993
Biosphere 2
Eight people spent two years in a 1.27-hectare sealed world. Oxygen fell to about 14%, and the lesson was that a biosphere is harder to balance than to build.
2008-2010
Physico-chemical recycling in orbit
The ISS began turning urine and humidity into drinking water, and a Sabatier reactor started recovering oxygen from exhaled CO₂.
2015-2017
Crops in orbit
Astronauts ate the first lettuce grown on the ISS; the Advanced Plant Habitat followed with a closed, sensor-dense growth chamber.
2018-2024
Year-long closure on the ground
Lunar Palace 365 ran for 370 days at 98.2% closure; NASA's first CHAPEA crew lived 378 days in a 3D-printed Mars habitat analogue.
2021-2023
Oxygen from Mars
MOXIE ran 16 times on Perseverance, making oxygen from the Martian atmosphere day and night, across seasons.

Why not terraform?

Mars’s surface pressure is about 6 millibars, under 1% of Earth’s. A 2018 inventory of the planet’s accessible carbon dioxide, in polar caps, soils, and minerals, found that releasing all of it would raise pressure to perhaps 20 millibars: still far too thin to breathe, to keep water liquid for long, or to walk outside without a pressure suit. Later proposals to warm the planet with engineered particles are interesting physics, but they address temperature rather than pressure or oxygen, and they are hypotheses, not programmes.

The ecosystems Mars can support in any plannable future are inside pressurised volumes. That makes the relevant curves the ones in this report: closure, power, and reliability, not planetary engineering. There is also a question engineering cannot answer: whether Mars should be altered before it has been searched thoroughly for life of its own.

Who is building what

Agencies and research institutes hold most of the flight and long-duration evidence. Companies are building the transport, construction, and oxygen hardware a settlement would depend on. Search the record, or filter by what they build.

NASAISS ECLSS, MOXIE, Veggie and APH, CHAPEAPhysico-chemical life support in orbit, oxygen from Martian air, plant growth in flight, and year-long Mars-habitat analogues

Reported evidence: ISS water recovery reached 98% in 2023; MOXIE made 122 g of oxygen on Mars in 16 runs; the first CHAPEA crew lived 378 days in a 3D-printed Mars habitat analogue.
Announced next step: Lunar surface systems under Artemis as the proving ground for Mars life support, power, and habitats.
Unresolved risk: Budget and schedule pressure on surface systems, and no flight-tested food or oxygen-closure system sized for a Mars crew.

ESAMELiSSAA compartmentalised microbial and plant loop that turns waste into oxygen, water, and food

Reported evidence: A pilot plant in Barcelona has run linked compartments continuously with animal crews standing in for humans; components have flown as experiments.
Announced next step: Integrated higher-plant and microbial compartments at human scale.
Unresolved risk: Each added compartment adds failure modes; loop stability at full closure with a human crew is not shown.

Beihang UniversityLunar Palace 1Ground-based bioregenerative habitat with crops, insects, and microbial waste treatment

Reported evidence: The 370-day Lunar Palace 365 mission reported 100% oxygen and water regeneration, 73% of food dry mass grown inside, and 98.2% overall closure.
Announced next step: A lunar base life-support design derived from the facility.
Unresolved risk: Ground gravity, abundant Earth power, and no radiation; mass and power were never constrained to flight levels.

Institute of Biophysics, KrasnoyarskBIOS-3Sealed algae and crop habitat, the first long human closed-ecosystem runs

Reported evidence: Three-person crews lived up to 180 days (1972-1973) with about 91% overall regeneration.
Announced next step: Historic; the data remain a baseline for bioregenerative design.
Unresolved risk: Relied on stored food for part of the diet and on external power and heat rejection.

SpaceXStarshipFully reusable methane-oxygen transport, with return propellant made on Mars from CO₂ and ice

Reported evidence: Suborbital and orbital-velocity test flights of the full stack, booster catches, and in-flight propellant-transfer development.
Announced next step: Uncrewed Mars landings in an upcoming launch window, followed by crews (Target).
Unresolved risk: Orbital refilling at scale, landing heavy payloads on Mars, and a propellant plant that has only been demonstrated at gram scale.

Collins AerospaceISS oxygen, water, and CO₂ systemsElectrolysis, water processing, and Sabatier reduction (Hamilton Sundstrand heritage)

Reported evidence: Hardware behind the ISS Oxygen Generation Assembly, Water Recovery System, and the Sabatier reactor that recovers about half the oxygen in exhaled CO₂.
Announced next step: Lighter, more reliable exploration-class life support.
Unresolved risk: ISS hardware depends on frequent spares and crew maintenance that a Mars mission cannot resupply.

OxEon EnergyMOXIE electrolysis stackSolid-oxide cells that split CO₂ into oxygen and carbon monoxide

Reported evidence: Built the solid-oxide stack (as Ceramatec) that ran MOXIE at up to 12 g of oxygen an hour at 98% purity on Mars.
Announced next step: Stacks scaled roughly two orders of magnitude for crew and propellant production.
Unresolved risk: Thermal cycling, dust, and degradation across thousands of hours, rather than 16 short runs.

Sierra SpaceVeggie, Advanced Plant Habitat, TCPS, LIFEPlant-growth chambers, trash-to-resource processing, and inflatable habitats

Reported evidence: Its ORBITEC heritage built Veggie and the Advanced Plant Habitat that have grown crops on the ISS since 2015 and 2017.
Announced next step: Inflatable LIFE habitat modules for commercial stations and beyond.
Unresolved risk: Flight plant growth is supplemental: grams of salad, not a diet.

Interstellar LabEden and BioPod modulesModular controlled-environment growth units for space and Earth

Reported evidence: Terrestrial pods and NASA-supported research on compact bioregenerative food production.
Announced next step: Plant modules suited to lunar and Mars habitats.
Unresolved risk: Power per kilogram of food, and proving closure rather than growth.

Paragon Space DevelopmentCommercial ECLSSThermal and life-support systems for crewed vehicles and stations

Reported evidence: Founded by Biosphere 2 veterans; supplies thermal control and life-support subsystems to commercial spaceflight programmes.
Announced next step: Closed-loop systems for commercial stations and surface habitats.
Unresolved risk: Commercial demand for high-closure systems is thin while low-Earth orbit can still be resupplied.

ICONMars Dune Alpha, Project OlympusRobotic 3D printing of structures from local material

Reported evidence: Printed the 158 m² Mars Dune Alpha analogue habitat for NASA's CHAPEA; holds a NASA contract to develop lunar surface construction.
Announced next step: Printing landing pads and shelters from lunar regolith.
Unresolved risk: Binders, curing in vacuum and cold, and dust are unsolved off Earth; nothing has been printed on another world.

AI SpaceFactoryMARSHAPrinted habitat shells from basalt fibre and plant-derived polymer

Reported evidence: Won NASA's 3D-Printed Habitat Challenge in 2019 with a printed, pressure-tested subscale structure.
Announced next step: Regolith-based construction for lunar and Mars shelters.
Unresolved risk: The winning material relied on imported binder; true local construction needs local binders.

Blue OriginBlue AlchemistMolten-regolith electrolysis that yields metals, silicon for solar cells, and oxygen

Reported evidence: Announced production of solar cells and oxygen from lunar regolith simulant in 2023.
Announced next step: Lunar power and oxygen made on the surface.
Unresolved risk: Very high temperatures and electrode life; lunar chemistry differs from Mars, where oxygen is easier to pull from the air.

COSPARPlanetary protection policyInternational guidance on biological contamination of other worlds

Reported evidence: Mars landers are categorised by where they go and whether they search for life; human missions are still under active policy development.
Announced next step: Rules for crewed missions that will inevitably carry microbes.
Unresolved risk: Every open ecosystem leaks; policy may constrain where habitats can go and what they can vent.

Capabilities are reproduced from missions, publications, and public announcements. An announced landing date is a Target, and a demonstration on Earth or the Moon is not a result on Mars.

Part II: Where progress is stuck

The remaining constraints are power, reliability, and biology

The field has moved from carrying everything, to recycling water and air, to the problem of feeding people from a system that must run for years without help.

Reliability without resupply

The ISS keeps its life support running with spares shipped every few months. A Mars crew has one delivery every 26 months, so mean time between failures, repairability, and on-site manufacturing of parts matter more than peak efficiency.

Power

Crops, oxygen, heat, and water processing all draw on it. Nothing flown to Mars has produced more than a few hundred watts; a settlement needs tens to hundreds of kilowatts through dust storms.

Food at scale

Growing a diet has only been demonstrated on Earth, with Earth power, gravity, and repair crews next door. Crop yield at Mars gravity and under Mars light is unmeasured.

Radiation

A 900-day mission can approach NASA's 600 mSv career limit before any shielding advantage from habitats is counted.

Ecological stability

Closed biological systems drift. Biosphere 2's oxygen problem took over a year to diagnose. A settlement needs sensing and control that keep dozens of coupled processes stable.

Planetary protection

Crewed habitats will leak microbes. Rules for where they can go and what they can vent, especially near ice that might hold evidence of life, are unsettled.

What pushes the curves next

01

Surface fission power

Tens of kilowatts that do not care about dust storms turn crops and oxygen plants from luxuries into baseline systems.

Condition: a reactor flown and run on the Moon first

02

Oxygen plants scaled up

Solid-oxide electrolysis roughly a hundred times MOXIE’s output, running for years, supplies breathing oxygen and the oxidiser for the trip home.

Condition: stack lifetime through thousands of thermal cycles and dusty intake air

03

Crops bred for closed systems

Dwarf, high-harvest-index varieties and protein from algae or insects raise edible calories per watt and per square metre.

Condition: yield measured under partial gravity and realistic light

04

Maintainable, printable hardware

Life support designed to be repaired with parts printed on site shortens the chain of failures that a 26-month resupply gap cannot tolerate.

Condition: printable materials that meet pressure-vessel and medical standards

An optimistic view, with conditions

A Mars base needs a greenhouse and a reactor, not a new physics

Every loop has a working demonstration somewhere: 98% water recovery in orbit, oxygen from Martian air, a year of 98% closure on the ground. None has been integrated, scaled, and run without help on another world. If transport costs keep falling and surface fission power flies, the remaining work is engineering integration and endurance testing, done first on the Moon, where help is three days away.

Now to 2030

Prove the parts on the Moon

Surface power, oxygen extraction, and small plant-growth systems operating for months on the lunar surface. Continued ground analogues at flight-realistic power.

2030s

Pre-deployed plants on Mars

Uncrewed landings that set up power, oxygen, and water production before a crew arrives, so the return propellant exists before anyone depends on it.

Longer horizon

A base that feeds itself

Most calories grown on site, stored-food reserves for failed harvests, and resupply shrinking toward spare parts and seeds.

View the annual scorecard

Metric	Record through September 2026	What a self-sustaining base needs
Water recovery in flight	98% (ISS, 2023)	98%+ for years with little resupply
Oxygen from exhaled CO₂ in flight	About 50% (ISS Sabatier)	Near-complete, or replaced by local production
Oxygen made on Mars	12 g an hour peak; 122 g in total	Kilograms an hour for years
Food grown, flight	Supplements only	A majority of calories
Food grown, ground analogue	73% of dry mass for a year (Lunar Palace 365)	Most calories at flight-realistic power and mass
Surface power	Hundreds of watts (rovers)	Tens to hundreds of kW, dust-storm proof

Baselines are reported results. Targets are editorial benchmarks, not forecasts.

There is more than one finish line

SurviveA crew lives on Mars on supplies brought from Earth.
RecycleWater and air loops close at ISS levels, without resupply.
ProduceOxygen, water, and return propellant come from Mars.
GrowA majority of calories are harvested on site.
RepairMost failures are fixed with parts made on site.
SustainThe base grows without needing more from Earth each window.

Sources, method, and boundaries

Figure 1 plots reported recovery rates for flight hardware and food shares for ground habitats; the ground values for BIOS-3 and Biosphere 2 are approximate. Figures 3 and 4 are illustrative models with daily needs rounded from NASA baseline values. Evidence labels follow the house standard: Measured (directly demonstrated), Derived (calculated from measured data), Projected (modeled future outcome), Target (announced goal), and Editorial inference (interpretation of evidence). Company and agency dates are Targets unless stated otherwise.

Closure: The share of a consumable that is regenerated inside the system rather than resupplied.
ISRU: In-situ resource utilisation: making oxygen, water, propellant, or building material from local resources.
Sabatier reaction: CO₂ + 4H₂ → CH₄ + 2H₂O. On the ISS it recovers water from exhaled CO₂; on Mars it could make methane propellant.
Conjunction-class mission: A Mars round trip of about 900 days, including a surface stay of more than a year while the planets realign.

NASA: MOXIE completes its Mars mission (2023)NASA ICES: Status of ISS water management and recovery (2023)NASA: Environmental Control and Life Support System overview NASA: ISS ECLSS technology evolution for exploration Acta Astronautica: A case for supporting human long-term survival on the Moon, Lunar Palace 365 (2024)bioRxiv: Establishment of a closed artificial ecosystem to ensure human long-term survival on the Moon Bios-3: Siberian experiments in bioregenerative life support Dartmouth Alumni Magazine: Biosphere 2, what really happened Science: Measurements of energetic particle radiation in transit to Mars (2013)Science: Mars surface radiation environment measured by Curiosity (2014)Nature Astronomy: Inventory of CO₂ available for terraforming Mars (2018)