The tree · Biology · Happens to the world · Plays out over the whole window
People live for a year in a spinning habitat with Earth-normal gravity
The full version of the habitat route: a structure large enough (roughly a hundred metres or more in radius, spinning about three times a minute) that its occupants feel Earth's gravity and need far less adaptation than partial gravity asks of them. If partial gravity turns out to be unlivable, this is the only route to a Belt, and it is the route some space futurists prefer anyway.
The test: what counts as it having happened
A rotating habitat produces between 0.9 and 1.1 of Earth's gravity at the level where the crew live and is continuously occupied by at least ten people for twelve months, with no occupant medically evacuated during the year, confirmed by the operator and independent tracking.
Settled by: The operator's records and independent orbital tracking
The odds, by how long I live
| baselineto 2071 ± 8 | moderateto 2080 | strongto 2095 | radicalto 2136 | openno deadline |
|---|---|---|---|---|
| 35% | 42% | 55% | 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 a spin demo and hundred-metre assembly, an Earth-gravity habitat for ten people is a deployment milestone rather than a breakthrough; what holds it near one in three by 2071 is motive, since the partial-gravity route may make it unnecessary, not difficulty, which the dependencies already carry.
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% (too small to tell apart from chance).
| 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% | 1.4% | 3.9% | 11% | 16% |
| If this settled no now | 0.4% | 1.2% | 3.2% | 10% | 14% |
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 year in a spinning habitat at Earth gravity was raised: given the spin test and hundred-metre assembly, ten people for a year is a deployment, not a breakthrough 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
No news of a built or occupied Earth-gravity spinning habitat. Gateway Foundation and Orbital Assembly results were old plans with slipped dates, and no 2026 funding announcement was found.
-
2026-10-04 Nothing new
No rotating habitat with Earth-normal gravity exists or is under construction in orbit; results are only concepts such as Voyager Station and Von Braun, with repeated delays.
-
2026-09-19 Nothing new
No rotating Earth-gravity habitat exists or is occupied; Orbital Assembly's Voyager Station remains an unbuilt design study, with nothing new in the window.
Revisions
| Date | Field | From | To | Why |
|---|---|---|---|---|
| 2026-09-19 | resolution | at least ninety percent of Earth's gravity, occupancy only | 0.9 to 1.1 of Earth's gravity at the level where the crew live, with no occupant medically evacuated during the year | Step 27 outside-model review, item 42 (docs/reviews/2026-09-19-rulings.md): the one-sided bound let a 1.5 g habitat count, and the habitat route needed a health test so that the either-route hedge (item 48) means the same thing by either route. Decided September 19th, 2026. |
| 2026-09-19 | description | need no adaptation at all | need far less adaptation than partial gravity | Step 27 outside-model review, item 42: rotation and head movements still cause motion effects at Earth-normal gravity. Decided September 19th, 2026. |
| 2026-09-19 | probability | 0.25 / 0.32 / 0.45 / 0.70 / 0.80 | 0.35 / 0.42 / 0.55 / 0.78 / 0.85 | Step 27 outside-model review, item 43 (docs/reviews/2026-09-19-rulings.md): the first estimate carried the prerequisites' difficulty into the conditional a second time; the motive discount survives, the difficulty discount does not. Decided September 19th, 2026. |
Notes
Edge drawn at step 7 (September 8th, 2026): a habitat with Earth-normal gravity is a hundred-metre-class structure, so it needs orbital assembly to have been done at that scale. Step 27, item 48 (September 19th, 2026): the health clause added here is what makes B-long-term-off-earth-living-by-some-route mean the same minimum by either route; the hedge node itself is unchanged.
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.