New calculations of the composition of TRAPPIST - 1f, the fifth planet from the star, suggest a relatively thin layer of water (still far deeper than anything found on Earth) gives way to ice VI and ice VII, two different forms of ice that can form under high pressures. (sciencenews.org)
This revealed a very thin layer of water — just five molecules thick — at the interface between the ice and silica. (sciencemag.org)