The Upsiders were the space born residents of the Sol System during the 3rd Century PD.
They were broken into various communities with extremely limited immigration between communities by the suspicious Earth Union. Although the Upsiders crewed the vessels of the Customs Patrol, only the Earth-born could obtain a Customs Patrol officers commission. Within the Upsiders, there various political groups, such as the Spacers and the Sols. (HHA6.1: BTB)