Mercury

An extremely hot, inhospitable planet, Mercury is pockmarked by interplanetary debris and is devoid of surface atmosphere. As a result, it is constantly bombarded by dangerous radiation from Sol, the star in this system.

The colony on this planet resides exclusively in underground bio-domes. The colonizing race, known as the Mercurians, are adapted to the rigorous conditions of Mercury. Benefitting from the chemical composition of the planet's interior, Mercurians create various alchemical substances, including medical supplies.