The tree · Energy · Happens to the world · Plays out over the whole window
A fission-electric power system built for spaceflight makes a hundred megawatts of electricity
A reactor driving a generator, with radiators to shed the heat, is the one way to make electricity in deep space that has been built and ground-tested for decades, at up to a few hundred kilowatts. Scaled up a few hundredfold, it could power large electric thrusters or, if made light enough, a fast drive without waiting on fusion. This is the fission route toward a compact power source at fast-drive scale.
The test: what counts as it having happened
A fission reactor power system designed for spaceflight, including its power conversion and the radiators it would use in vacuum, produces at least one hundred megawatts of net electrical output for at least one continuous hour, in a ground test or in space, confirmed by the developer's test record and the responsible agency's report. A land-based power station not designed to fly does not count.
Settled by: The developer's test record and the responsible agency's report
The odds, by how long I live
| baselineto 2071 ± 8 | moderateto 2080 | strongto 2095 | radicalto 2136 | openno deadline |
|---|---|---|---|---|
| 4% | 7% | 14% | 28% | 38% |
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 25th, 2026.
Why these numbers: First estimate, September 25th, 2026, proposed by Claude with the node and accepted by me October 2nd, 2026. The largest space reactor systems ever designed aimed at a megawatt or less and none has flown at that power; a hundred megawatts built to fly needs a mission that cannot be done any other way and decades of funding, which no program has yet found. Low by 2071, rising with the long windows as fast transit to the outer system becomes worth paying for.
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.
The last 2 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.
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2026-11-01 Nothing new
No hundred-megawatt flight-type reactor program exists; the 2026 White House space nuclear memo targets at least 100 kWe for the 2030s, and Antares reached zero-power criticality on June 4th, 2026, outside the window.
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2026-10-04 Nothing new
No 100 megawatt space fission test was reported; the nearest flight plan is SR-1 Freedom at about 20 kilowatts electric, scheduled for end of 2028.
Notes
Added September 25th, 2026 as a route under E-compact-power-source-at-fast-drive-scale (candidate 4 of docs/proposal-function-over-route-2026-09-25.md, I approved September 25th, 2026). It sets no weight limit: the function step above it carries the one-kilogram-per-kilowatt bar. Not marked a long shot because it is a scaling problem on known physics.
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The record itself is data/E-energy.toml in the public repository.