Forecast
A substantially self-sustaining human settlement exists beyond Earth by 2126.
Last revised Sep 11, 2026.
Current estimate
probability this has happened by each date
A permanently inhabited site beyond Earth operates for five consecutive years without receiving food, water, oxygen, or other critical consumables from Earth. Crew rotation is permitted and does not break the requirement; import of spare parts and equipment does not break it; import of any consumable does. Reproduction is NOT required and is tracked separately as hf-forecast-0022.
Resolution criteria
- 2126
- A permanently inhabited site beyond Earth operates for five consecutive years without receiving food, water, oxygen, or other critical consumables from Earth. Crew rotation is permitted and does not break the requirement; import of spare parts and equipment does not break it; import of any consumable does. Reproduction is NOT required and is tracked separately as hf-forecast-0022.
Probability history
| Revised | State | p(2035) | p(2050) | p(2100) |
|---|---|---|---|---|
hf-forecast-0023 | researched | — | — | — |
hf-forecast-0013 | initial prior | — | — | — |
Strongest evidence for
- Water recovery aboard the ISS reached about 98 percent, so a consumable loop can be nearly closed in real flight hardware (hf-evidence-0038).
- Oxygen closure is about 50 percent with a named chemical cause and a stated target above 75 percent, which makes it an identified engineering problem rather than an unknown (hf-evidence-0039).
- Lunar surface radiation measures about 60 microsieverts per hour, and the instrument team's own mitigation is covering a habitat with lunar soil, which is mass already present at the site (hf-evidence-0037).
- Biosphere 2's oxygen loss was later attributed to concrete curing absorbing carbon dioxide, a specific correctable fault rather than a general limit on closure (hf-evidence-0041).
Strongest evidence against
- Food closure is the binding loop: the most advanced engineered programme reports 20 to 40 percent, the ISS imports all of it, and one person needs roughly 40 to 50 square metres of intensively lit crops (hf-evidence-0040).
- The best closed system ever built around people, Biosphere 2, ran two years with eight people and still required oxygen injected from outside; BIOS-3 imported animal protein and removed crew waste (hf-evidence-0041).
- The longest continuous human spaceflight is 437 days, under a quarter of the 1,825 days required, achieved in microgravity with full resupply and return available (hf-evidence-0036).
- Long-term human health at 0.17 or 0.38 g is entirely unmeasured. Across 43 studies none investigated long-term effects, and the longest true partial-gravity exposure on record is about 75 hours (hf-evidence-0035).
Present uncertainties
- Whether partial gravity is survivable long term, which is unmeasured rather than known, and whether food closure scales.
Next discriminating observation
The first mammal studied for a year or more at lunar or Martian gravity; and the first bioregenerative system anywhere demonstrating sustained food closure above 50 percent.
Sources
- Effects of gravity, microgravity or microgravity simulation on early mouse embryogenesis
No mammalian or vertebrate animal has completed its entire life cycle from conception to adulthood while in space. The two space embryo experiments both stopped at the blastocyst stage after about four days: 3,400 non-frozen two-cell mouse embryos in 2020, which showed significant double-strand DNA breaks, increased single-strand breaks and global hypomethylation, and 720 frozen embryos in 2023. No attempt has ever been made to produce offspring from embryos developed in space.
Limit: This is a complete absence of attempted evidence rather than evidence of failure. Nobody has tried and failed to raise a mammal in space; nobody has tried. The DNA damage seen at blastocyst stage is a concerning signal from small samples, not a demonstration that development cannot proceed.
Fetched and confirmed directly by the master agent.
- Human biomechanical and cardiopulmonary responses to partial gravity, a systematic review
Across 43 included studies, none investigated long-term effects. The longest actual human exposure to true partial gravity on record is up to 75 hours of continuous exposure during the Apollo surface missions. The authors conclude that future research must address long-term physiological effects and define minimal gravity thresholds and exposure times needed to maintain physiological systems.
Limit: Absence of evidence, not evidence of harm. It does not show partial gravity is dangerous; it shows nobody has measured it. A rotating habitat or centrifuge would sidestep the question entirely.
Fetched and confirmed directly by the master agent.
- Longest continuous human spaceflight and the reversibility of its effects
The longest single continuous human spaceflight is 437 days, under a quarter of the 1,825 days this forecast requires, achieved in microgravity with full Earth resupply and return capability. Lower-limb bone loss on missions beyond 30 days runs at about 0.8 percent per month with cumulative lumbar and pelvic loss around 6.2 percent; six-month missions show quadriceps loss around 12 percent; clinically significant optic disc oedema appears in roughly 15 percent of astronauts after long-duration flight, with subclinical optic disc changes in nearly all. About 91.3 percent of one astronaut's spaceflight-induced gene-expression changes reverted after return, meaning some did not.
Limit: Microgravity is not partial gravity and may be the harsher case, so these figures could overstate the difficulty on a lunar or Martian surface. Countermeasures improved substantially across the period these records span, and a century is long. The 437-day record was set in 1995.
Retrieved by a delegated source worker and not independently re-fetched.
- First measurements of the radiation dose on the lunar surface, Chang'e-4 LND
The Lunar Lander Neutrons and Dosimetry instrument on Chang'e-4 measured an equivalent dose rate of about 60 microsieverts per hour on the lunar surface, more than 200 times the dose at Earth's surface and 5 to 10 times that of a long-haul flight. The instrument team's stated mitigation is to cover a habitat with a thick layer of lunar soil, which they say would reduce cancer and other disease risk.
Limit: A measurement of the environment, not of human outcomes, and it does not establish the habitat mass, cost, or construction method that adequate shielding would require. Surface dose says nothing about the separate transit dose.
Fetched and confirmed directly by the master agent from the instrument team's own page, resolving a gap a delegated worker flagged as unverified after the journal returned 403.
- NASA achieves water recovery milestone on the International Space Station
Total water recovery aboard the ISS reached about 98 percent once the Brine Processor Assembly began processing the residue of urine distillation, up from 93 to 94 percent before it came online.
Limit: Ninety-eight percent is not one hundred: a five-year stay still loses water steadily, and this figure covers the water loop alone while food remains entirely imported.
Retrieved by a delegated source worker from a primary document and not independently re-fetched.
- Spacecraft Oxygen Recovery, NASA
The state-of-the-art Sabatier system aboard the ISS recovers about 50 percent of the oxygen from exhaled carbon dioxide. NASA's stated goal for long-duration exploration is more than 75 percent with a stretch goal of 100 percent. The limitation is named precisely: the Sabatier lacks sufficient hydrogen because it produces methane as a byproduct, and that methane carries hydrogen out of the loop.
Limit: This covers oxygen recovered from exhaled carbon dioxide specifically, not total station oxygen closure, since oxygen is also generated by electrolysing water. It is an engineering target, not a demonstrated result.
Fetched and confirmed directly by the master agent.
- Food production for a bioregenerative life support system, scale and closure
Approximately 40 to 50 square metres of crops grown under high light intensity would be needed to supply enough dietary calories for one person. The most advanced engineered bioregenerative programme reports food closure in the range of 20 to 40 percent, against effectively zero food closure aboard the ISS, where all food is imported.
Limit: Area figures depend on crop selection, lighting intensity and diet assumptions, and closure percentages come from ground research facilities rather than from anything flown. None of this shows food closure is unreachable, only that it is the least advanced loop.
Retrieved by a delegated source worker from a primary document and not independently re-fetched.
- Biosphere 2 and BIOS-3, the closed ecological systems actually built
Biosphere 2's first closure ran two years from 1991 to 1993 with a crew of eight, achieving an annual air leakage rate under 10 percent measured by tracer gases, and recycling water, food and waste throughout. Oxygen nevertheless fell from the normal 20.9 percent and had to be injected from outside. BIOS-3 in Krasnoyarsk, a 315 cubic metre facility with a crew of up to three, ran crewed closure experiments but imported animal protein and, in its first phase, removed solid and liquid crew waste from the system.
Limit: Biosphere 2 was a biologically driven design from the early 1990s whose oxygen loss was later attributed to concrete curing absorbing carbon dioxide, a specific and correctable fault rather than a general law. Engineered systems such as MELiSSA take a different approach, and a century is a long time. Widely cited BIOS-3 closure percentages of about 95 percent trace to a source that could not be retrieved and are deliberately excluded.
Retrieved by a delegated source worker from a primary document and not independently re-fetched.