The Maker: Adventures in Time and Space
Helion (pronounced HE‐lee‐on) is a planet located in the deep expanses of space. Located just outside the Checkmark Nebula, the planet is a very rocky world that is covered in a sea of mercury. The mercury sea has strange creatures that live in it, and that resemble silverfish insects. These insects are known by the name Mercrites, and have been known to attack people. Because the Mercrites usually live in liquid metal, they can also consume most metals, making them a threat to bursting space suits that are needed on the surface of Helion. Helion has only a very thin atmosphere, and the air is fairly toxic because of the heavy metals that are suspended in it. It is possible to take off a spacesuit and breath on
the surface, but only for a very short period of time.
Helion is of course attractive to space explorers for its source of mercury, which many Time Lords have also used to repair fluid power links that needed the element. However, other than short visits, the planet is remote and inhospitable. There is no vegetation on the planet, and the surface is rocky with no soil, water, or plant life of any kind. Likewise, there are significant health risks to anyone who remains on the planet for an extended period
without an environmental suit. No extended settlement of Helion has been attempted.