Some planets around other stars – and even some moons in our solar system – could have life hidden under layers of weird high-pressure ice, in oceans far deeper than Earth’s.
Extreme pressures can create unusual forms of ice rarely seen on Earth. To investigate what this means for other planets, Lena Noack at the Royal Observatory of Belgium and her colleagues modelled rocky worlds with very deep oceans.
They found that on a planet with the mass of Earth, a layer of high-pressure ice can form in oceans at depths of around 170 kilometres – more than 15 times that of the lowest point in Earth’s oceans.
Given ample heat from the planet’s interior, water can remain liquid under the ice long enough for life to take hold. The model works for planets up to 10 Earth masses – beyond that, the pressure of the planet’s gravity prevents a second layer of water from forming below the ice.
Noack says two exoplanets that could host such oceans are Kepler 62e and 62f, both of which were discovered in 2013. Their radii are 1.6 and 1.4 times that of Earth, respectively, and although their masses are uncertain, they might have densities that indicate a high water content.To read more, click here.