Psilon is a planet that has unbearably hot deserts as well as lava stone fields and volcanoes. The temperatures allow for exploration in protective suits, but the proximity to Sopa-Kul and the pirates prevent further exploration.
Between the sand dunes and the lava flows, the remains of a vanished civilization can still be seen. Also, the wrecks of space ships with unknown technology confirm this. Apart from plunderers, whose finds are only worth something to curiosity collectors, the place is abandoned.