Altair's biosphere was destroyed when technology left it highly radioactive, forcing about 1000 survivors to live underground and to take on synthetic bodies for survival. Hubald, the creator of the synthetic technology, died, and others left through the gate or were destroyed on the planet's toxic surface. Wallace was the last to go, 11,000 years ago. Harlan, the only remaining survivor of Altair, had been alone since then, maintaining the enormous and aging underground facility. He created synthetic duplicates of SG-1 as companions, however, despite their promise to remain on the planet and bury the gate, the synthetic team continued to go on off-world missions.
Location: Port Mann Power Station
Cross Reference: Comtrya, Harlan, Synthetic Duplicates
Episode Reference: Tin Man