The tree · Biology · Happens to the world · Could be decided within 1 to 5 years
A mammal is conceived, born, and weaned in partial gravity
Whether pregnancy and early development work in less than Earth's gravity is the biggest open question in off-Earth biology and has never been tested end to end. Mice have flown in a spinning enclosure on the space station that produces lunar or Martian gravity, so the experiment is within reach. A live, weaned litter is the first evidence that a settlement, rather than a work camp, is biologically possible.
The test: what counts as it having happened
A peer-reviewed publication reports that a mammal was conceived, carried to term, born, and weaned entirely at a sustained gravity level between one-sixth and one-half of Earth's, whether in a centrifuge in orbit or on the Moon or Mars, with offspring surviving to weaning, in an experiment run with a control group.
Settled by: The peer-reviewed publication and the space agency's mission record
The odds, by how long I live
| baselineto 2071 ± 8 | moderateto 2080 | strongto 2095 | radicalto 2136 | openno deadline |
|---|---|---|---|---|
| 80% | 82% | 85% | 92% | 95% |
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 8th, 2026.
Why these numbers: The centrifuge hardware exists and the experiment is cheap next to everything else in the tree; the risk is that partial-gravity gestation fails biologically, not that nobody tries. A failed attempt leaves the node open: another species, gravity level, or method can still resolve it.
What this one is worth
Nothing. The headline number does not rest on this step at any remove, so however it turns out, the chance that I live and work off Earth does not change. That is not a judgement that it does not matter. It is what the tree says: this step feeds a tier above the one the headline asks about, or sits beside the equation rather than in it.
What the ledger says about this step
- Forty-one steps had their criteria tightened so that two readers would agree when each has happened, with no number moved for that alone 2026-09-20 The tree itself changed
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 report in the past week of a mammal conceived, born and weaned at sustained partial gravity. The JAXA MARS centrifuge study (0.33 g, 0.67 g) on the ISS involved adult mice and offspring but no peer-reviewed pup outcomes were found, and the multigenerational partial-gravity habitat is only a concept.
-
2026-10-25 Nothing new
No peer-reviewed report of a mammal conceived, born and weaned in partial gravity appeared in the week to October 25th, 2026. Results show only JAXA's earlier centrifuge mouse work (2017, 2019) and a partial-gravity mouse study on the ISS that has no published results paper.
-
2026-10-18 Nothing new
No peer-reviewed report of a mammal conceived, born and weaned in partial gravity appeared in the week to October 18th, 2026. Results show only JAXA's centrifuge platform and its earlier mouse missions, plus the Shenzhou-21 mouse that gave birth to nine pups on December 10th, 2025 after a microgravity flight, which is not partial gravity and has no journal paper.
Revisions
| Date | Field | From | To | Why |
|---|---|---|---|---|
| 2026-09-19 | resolution | no control group required | with a control group; any gravity in the range still counts | Step 27 outside-model review, item 49 (docs/reviews/2026-09-19-rulings.md): a control group is standard and costs nothing; replication at a specific destination gravity was declined as a research programme rather than a leaf. Decided September 19th, 2026. |
| 2026-09-19 | rationale | said a biological failure would resolve the node no | a failed attempt leaves the node open | Step 27 outside-model review, item 49: the rationale overstated the criterion, which names no single experiment. Decided September 19th, 2026. |
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.