Two new superionic ice phases could explain Neptune, Uranus magnetic — SkimNews
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- Gunnar Weck at the French Alternative Energies and Atomic Energy Commission led a team that discovered hexagonal close-packed (hcp) ice by crushing water in a diamond anvil to millions of atmospheres and heating it with a laser to thousands of degrees.
- hcp ice is a superionic phase in which oxygen stays locked in a solid lattice while hydrogen moves like a liquid, making it far more electrically conductive than ordinary ice.
- Israel Osmond at the University of Edinburgh independently identified a second new phase called ice XXII, which is stable at pressures nearly double those required for hcp ice.
- Superionic conductivity near the surfaces of ice giants could explain why Neptune and Uranus have magnetic fields that are tilted and off-centre, rather than the dynamos at the centres that drive Earth's field.
- Weck says the next research step is precisely mapping the transition lines between phases to determine at what depth each superionic ice can exist within Neptune and Uranus.
- Behaviour and deformation of each ice phase under planetary conditions — not just how charge flows through them — will determine what magnetic fields they can ultimately produce.
- The findings are published in Physical Review Letters (DOI: 10.1103/sdrk-3m4t), adding two pieces to what researchers describe as an extraordinarily complex puzzle of ice-giant physics.
Why it matters: Two independent labs converging on superionic ice phases gives planetary scientists concrete candidates for the long-standing puzzle of Neptune and Uranus's oddly tilted magnetic fields, and the next step — mapping transition lines to depth — could let spacecraft-era anomalies be matched to specific ice layers inside the ice giants.
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