# They Found Water on an Interstellar Comet. They Never Saw the Water.

- slug: they-found-water-on-an-interstellar-comet-they-never-saw-the-water
- date: 2026-04-23
- category: Space & Aerospace

ALMA measured a D/H ratio 30 times higher than Earth’s oceans in the interstellar comet 3I/ATLAS — but only by modeling methanol emissions, because the actual water fell below the telescope’s detection threshold.

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