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Title: Why does Venus have no internally generated magnetic field?
Plain: Venus has an iron core roughly as large as Earth's but no magnetic field of its own. Either its core does not churn today or something else stops a dynamo (a self-sustaining magnetic generator made by flowing liquid metal).
Precise: Spacecraft limits put any intrinsic Venus dipole moment below roughly $1e-5$ of Earth's (approximate, from Pioneer Venus era data). Determine why the Venus core sustains no dynamo: low core-mantle heat flow under a stagnant lid with no inner-core growth, a fully liquid or fully solid core, or a compositionally stratified core formed without a late giant impact (Jacobson and coauthors, EPSL 2017, https://doi.org/10.1016/j.epsl.2017.06.023). An answer is a core state (radius, solid fraction, stratification) and core heat flow consistent with the measured tidal Love number $k_2$, the moment of inertia and a thermal history, including whether a dynamo operated in the past.
Settled by: Orbiter tracking that measures the Venus $k_{2}$ and moment of inertia precisely, combined with a search for remanent magnetization in old crust.
Kind: well-posed
Answer type: identification
References: (empty)
Literature status: open
Status note: (empty)
Posed since: (empty)