The tree · Biology · Happens to the world · Could be decided within 5 to 20 years
A person lives a full year in partial gravity and comes home without disqualifying harm
The longest stays off Earth are a year or more in free fall on the space station, where bone, muscle, eye, and heart changes are well documented. Nobody has lived even a month in partial gravity. A year on the Moon (or in a spinning facility set to lunar or Martian gravity) with published health outcomes that would not bar a return trip is what a rotation of months, the A2 tier, assumes.
The test: what counts as it having happened
A person completes twelve continuous months at a sustained gravity level between one-sixth and one-half of Earth's, and a peer-reviewed report of their health outcomes after return to Earth finds no condition that the responsible agency's own standards would count as disqualifying for a further mission without a medical waiver.
Settled by: The peer-reviewed health report and the agency's crew-health standards
The odds, by how long I live
| baselineto 2071 ± 8 | moderateto 2080 | strongto 2095 | radicalto 2136 | openno deadline |
|---|---|---|---|---|
| 45% | 52% | 62% | 78% | 85% |
Each column is a different guess at how long I live, from current trends (baseline) to open-ended. The number is the chance this happens before that deadline, assuming everything it depends on happens first. As of September 19th, 2026.
Why these numbers: Given people on the Moon or a spin facility, the bar is one person at any gravity in the range under the agency's own standards, with repeated attempts and the most favourable gravity available; the first estimate's discount was mostly timing, not difficulty. Bone and eye effects in free fall are the warning, and the return-and-no-waiver clause keeps the bar honest.
What this one is worth
If this happened tomorrow and nothing else changed, the chance that I live and work off Earth by 2071 goes from 0.5% to 0.5% (too small to tell apart from chance). If it turned out no, the same number goes to 0.4% (−0.1 points).
| Longevity scenario | baseline2071 ± 8 | moderate2080 | strong2095 | radical2136 | openno deadline |
|---|---|---|---|---|---|
| The headline as it stands | 0.5% | 1.2% | 3.8% | 11% | 15% |
| If this settled yes now | 0.5% | 1.2% | 3.7% | 11% | 16% |
| If this settled no now | 0.4% | 0.9% | 3.0% | 9.5% | 13% |
This is what the site says in advance, before the thing happens. When it does, the
ledger entry that records it quotes this figure beside what actually followed, so a
reader can see whether the prediction held. Worked out at the run
2026-10-11-scan by holding this step at each outcome in turn and
playing the whole tree out again, 20,000 times per
scenario. That is a throw of the dice, so a move smaller than about
0.10 points is inside the noise rather than
a finding.
What the ledger says about this step
- A person living a year in partial gravity and coming home fit was raised: the bar is one person, at any gravity in the range, with repeated attempts 2026-09-20 Changed my mind
The last 3 checks
Once a week the tree is read against the news, node by node, against the test above. Open a line to see what that week held. Every check ever made on this node is on the Radar page.
-
2026-11-01 Nothing new
Nothing found since September 27th, 2026 on a person spending twelve months at partial gravity. Results were only background on lunar health risks and NASA research calls.
-
2026-10-04 Nothing new
No person has completed twelve months at partial gravity and no such health report appeared. Lunar surface stays remain planned at days to weeks, with Artemis crewed landing not before 2028.
-
2026-09-19 Nothing new
China's Shenzhou-23 crew, launched May 24th, 2026, includes a planned year-long stay, and NASA published cardiovascular and joint health findings in August and September 2026, but all of this is in microgravity aboard Tiangong or the space station, not the partial gravity the criterion requires.
Revisions
| Date | Field | From | To | Why |
|---|---|---|---|---|
| 2026-09-19 | resolution | health outcomes judged at any time, with no mention of return or waivers | outcomes after return to Earth, and fit for a further mission without a medical waiver | Step 27 outside-model review, item 46 (docs/reviews/2026-09-19-rulings.md): the node's name says the person comes home, and agency standards can be waived. Decided September 19th, 2026. |
| 2026-09-19 | probability | 0.35 / 0.42 / 0.50 / 0.65 / 0.70 | 0.45 / 0.52 / 0.62 / 0.78 / 0.85 | Step 27 outside-model review, item 47 (docs/reviews/2026-09-19-rulings.md): the conditional bar (one person, any gravity in the range, agency standards, repeated attempts) is permissive and the first rationale's discount was timing rather than difficulty; moved partway, with item 46 tightening the bar back somewhat. Decided September 19th, 2026. |
Notes
Edge drawn at step 7 (September 8th, 2026): a year in partial gravity needs either people on the Moon or a spinning facility; either route will do.
Think this estimate is wrong?
Here's how to tell me, and
what happens next.
The record itself is data/B-biology.toml in the public repository.