Season 10, Episode 20 - "Unending"
22 June, 2007
The Asgard summon SG-1 to tell them that their experiments to halt their genetic degeneration have failed, meaning they are a dying race. Because of this, the Asgard have decided to give "everything [they] have and know" to the Tau'ri. When the Ori show up, the Asgard commit mass suicide, and in order to preserve the Asgard legacy, Carter puts up a time dilation field around the Odyssey to prevent its destruction
