Lemuria

Lemuria (Kapteyn b) is a large terrestrial planet orbiting Kapteyn's Star. The planet is one of the oldest ever discovered, at over 11 billion years old. Lemuria is covered in vast icy planes that melt into oceans during the summer every 48 days. An ecosystem of fish like organisms exists beneath the vast ice sheets while lichen covers the surface. The oppressive gravity of the planet makes human habitation impractical, but its natural resources made it an important target of the Martian colonial efforts in the late 23rd century.