Size Duel deck / Space
Phobos
Length: longest axis
about 27 km (16.78 mi)
The larger of Mars’s two small, potato-shaped moons.
Sources and checks
Checked 2026-11-01: Researched by Codex (two independent publishers, verbatim quotes); every counted quote re-found on its page by the server check (content-verify, or content-verify-pdf for PDFs); scope and plausibility reviewed by Claude (AI build agent). Quotes are short passages from each source.
“a 27×22×18 km moon”European Space Agency: source, retrieved 2026-10-28; quote re-found by the server check
“Up to 27 km”Japan Aerospace Exploration Agency, MMX Science: source, retrieved 2026-10-28; quote re-found by the server check
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