A large terrestrial planet with wide, cold deserts, Sidon has a trace atmosphere that is principally carbon monoxide. Alliance planners found its gravity agreeable, however, and build a small domed research facility on the planet in the 2160s. The project was classified until recently, when Blue Suns mercenaries who allegedly attacked the facility were apprehended and brought to trial, revealing the facility's existence in open court.
Eager to counter the negative publicity, Elysium investment firms now advertise that Sidon is free of military facilities and just "minutes away" from the garden world, thanks to recent improvements in faster-than-light travel. Whether or not the marketing attracts development remains to be seen.