The tree · Energy · Happens to the world · Could be decided within 1 to 5 years
A radiator system sheds a megawatt of waste heat in vacuum for thirty days
In vacuum there is no air to carry heat away; everything a spacecraft does not radiate, it keeps. Every megawatt-class spacecraft, reactor, or drive is limited by the size and mass of the radiators that shed its waste heat, and no radiator flown to date handles more than a fraction of a megawatt. A radiator that rejects a full megawatt for a month in space is the binding constraint on megawatt spacecraft, tested on its own.
The test: what counts as it having happened
A radiator system in space rejects at least one megawatt of thermal power, averaged over thirty continuous days, as measured and reported by the operator from the system's own coolant temperatures and flow, whether the heat comes from a reactor, a power converter, or a test heat source.
Settled by: The operator's flight test record
The odds, by how long I live
| baselineto 2071 ± 8 | moderateto 2080 | strongto 2095 | radicalto 2136 | openno deadline |
|---|---|---|---|---|
| 80% | 85% | 90% | 94% | 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 20th, 2026.
Why these numbers: Deployable radiators at the hundred-kilowatt scale fly on the space station and megawatt-class vehicles are funded for the late 2020s, so the first megawatt radiator is a decade's engineering rather than a breakthrough; priced a little under the megawatt-spacecraft node because a spacecraft that runs thirty days resolves this by construction while a radiator test can also fly earlier and alone. Proposed by Claude September 20th, 2026 with the node's addition, I accepted.
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 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.
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2026-11-01 Nothing new
No megawatt radiator flew in the past week; NASA's MARVL work targets about 4 MW on the ground-analysis side and Texas A&M's small radiator flies spring 2027.
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2026-10-25 Nothing new
No megawatt radiator has flown or been dated for flight; results are NASA design studies (MARVL, about 3,000 square metres of surface) and ground tests of kilowatt-scale panels.
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2026-10-18 Nothing new
No megawatt radiator has flown or been dated for flight; results are ground chamber tests of kilowatt-scale panels and the cancelled DRACO nuclear rocket demonstration.
Notes
Added September 20th, 2026 under step 27, item 12 (docs/reviews/2026-09-19-rulings.md, decided September 19th, 2026): raised by Gemini as a missing node; a sibling of E-megawatt-spacecraft-operates-in-orbit that resolves first, not a dependency, and it gates nothing.
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The record itself is data/E-energy.toml in the public repository.