Mercury is the smallest and innermost planet in the Solar System. It is named after the Roman deity Mercury, the messenger to the gods.

Mercury is tidally or gravitationally locked with its sun in a 3:2 resonance, and rotates in an entirely unique way. As seen relative to the fixed stars, it rotates on its axis exactly three times for every two revolutions it makes around its sun. As seen from its sun, in a frame of reference that rotates with the orbital motion, it appears to rotate only once every two Mercurian years. An observer on Mercury would therefore see only one day every two years.

Mercury's surface appears heavily cratered and is similar in appearance to the Moon, indicating that it has been geologically inactive for billions of years. Having almost no atmosphere to retain heat, surface temperatures varies diurnally more than any other planet in Sol.

Later, around 2030 CE, the United Nations made their first attempts at establishing off-world research posts, and Mercury was one of their first targets. The UN setup a massive underground installation which came to be known as the Mercury Research Initiative and significantly contributed logistical support to the Bento Initiative.