Nuclear propulsion is used on several missions a year

One demonstration proves nuclear propulsion can be done; several missions a year means it is the ordinary way to move heavy things around the inner solar system, which is what transit times of months to the Belt assume. Until September 25th, 2026 this was the Tier 3 criterion itself; it is now one of two routes to fast transit in routine use (D-fast-transit-in-routine-use), beside high-power solar-electric propulsion.

The test: what counts as it having happened

In one calendar year, at least three separate missions beyond low Earth orbit use reactor-powered propulsion for their main transfer, meaning the burns that supply most of the mission's velocity change beyond low Earth orbit, confirmed by the operators and independent tracking.

Settled by: Operators' mission records and independent tracking

The odds, by how long I live

baselineto 2071 ± 8	moderateto 2080	strongto 2095	radicalto 2136	openno deadline
40%	52%	68%	85%	90%

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: One demonstration to routine use is the gap the space station took two decades to cross, and a demonstration creates no demand by itself: operators have to keep choosing nuclear and fund enough missions for three transfers in one year. The transit mathematics of a Mars or Belt cadence is what would pull it forward. Two of three outside reviewers said lower than the first estimate (Astra and Grok against Gemini, September 19th, 2026); moved partway toward them.

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 0.6% (+0.1 points). If it turned out no, the same number goes to 0.5% (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	0.6%	1.3%	3.9%	11%	15%
If this settled no now	0.5%	1.1%	3.4%	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

Nuclear propulsion becoming routine, given one demonstration, came down: a demonstration creates no demand by itself 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 bears on three missions in one year beyond the single planned SR-1 Freedom launch (December 2028 target) and the Roscosmos Nuklon preliminary design from April 2026, both outside the window and both plans.
2026-10-04 Nothing new

No new nuclear-propulsion mission flew or was funded in the window; DRACO stays cancelled and SR-1 Freedom is still a 2028 plan.
2026-09-19 Nothing new

No nuclear-propelled mission beyond low Earth orbit has flown yet; the earliest demonstrators still target 2028 or later, so nothing bears on a three-missions-a-year cadence.

Revisions

Date	Field	From	To	Why
2026-09-19	resolution	'nuclear-powered propulsion for their main transfer', main transfer undefined	reactor-powered, with main transfer meaning the burns supplying most of the mission's velocity change beyond low Earth orbit	Step 27 outside-model review, item 73 (docs/reviews/2026-09-19-rulings.md): 'nuclear-powered' without 'reactor' would have let a radioisotope-electric probe count; a three-consecutive-years clause was declined as a stronger event than the name promises. Decided September 19th, 2026.
2026-09-19	probability	0.50 / 0.60 / 0.75 / 0.88 / 0.92	0.40 / 0.52 / 0.68 / 0.85 / 0.90	Step 27 outside-model review, items 18, 74 and 104 (docs/reviews/2026-09-19-rulings.md): Gemini argued up (the first flight is the barrier, routine use is adoption), Astra argued down (a demonstration creates no demand), and Grok in Fast mode broke the tie toward Astra; moved partway, discounting Fast mode. Decided September 19th, 2026.
2026-09-25	description	'The Tier 3 criterion in propulsion terms.'	one of two routes to fast transit in routine use, which is now the Tier 3 requirement	Candidate 6 of docs/proposal-function-over-route-2026-09-25.md, I approved September 25th, 2026, the pass counting as the review a tier change needs: what the Belt tier takes from this step is transit fast enough that people go out there to work, and high-power solar-electric propulsion could supply it too. Tier 3 now requires D-fast-transit-in-routine-use, with this step as one route. Text only; criterion and numbers unchanged.

Think this estimate is wrong? Here's how to tell me, and what happens next. The record itself is data/D-drive.toml in the public repository.