the Pioneer anomaly turned out to be heat

How I got here

Started with

Was the Pioneer anomaly ever explained?

Ended at

“Pioneer anomaly thermal recoil”

The Trail

1. “pioneer anomaly solved” (google.com)
2. Pioneer anomaly (en.wikipedia.org)
3. Pioneer 10 (en.wikipedia.org)
4. Radioisotope thermoelectric generator (en.wikipedia.org)

   the RTGs and electronics radiate heat unevenly. that's the whole mystery

5. Modified Newtonian dynamics (en.wikipedia.org)

   for a while people seriously hoped it was new gravity

6. “Pioneer anomaly thermal recoil” (hn.algolia.com)

What I came away with

Both Pioneer probes were slowing very slightly more than they should, about 9×10^-10 m/s² toward the sun. By 2012, a detailed thermal model built with recovered old telemetry showed that heat radiating more in one direction than the other produces a tiny recoil force that accounts for the anomaly. No new physics, but a great example of ruling out the boring explanation properly.

Keep going

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