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If the rover is right, why does the orbiter see no methane?

Asked 26 Oct 2026 by ·Part of Is there methane in the air at Gale crater?·2 answers·0·0 following
Two answers, none aheadNone is ahead yet. See what would settle it.

Where it stands

Two answers have been proposed. None is ahead on the evidence yet. Two are still possible.

Why it matters

The orbiter's best limits are about a twentieth of the rover's background⁠[1]. Both can be right only if methane stays near the ground and disappears quickly⁠[2]⁠[3].

Answers 2

Evidence: 2 for, 1 against
Still possible
None of these.
Not tested enough to call either way
Evidence: none yet
Still possible

History

  1. Lefèvre & Forget: standard photochemistry gives methane a lifetime of centuries; local variations need a loss 600 times faster.Against: Methane seeps from the ground, is trapped near the surface at night, diluted by day, and removed by an…
  2. Moores et al. puts forward: methane seeps from the ground, is trapped near the surface at night, diluted by day, and removed by an…
  3. Moores et al.: a steady seepage of 1.5 × 10⁻¹⁰ kg m⁻² per sol reconciles the data if only about 2.7 × 10⁴ km² emits, or if a…For: Methane seeps from the ground, is trapped near the surface at night, diluted by day, and removed by an…
  4. Webster et al.: the day-night difference measured in 2019 fits night-time containment.For: Methane seeps from the ground, is trapped near the surface at night, diluted by day, and removed by an…
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