|This article is written from the Real Life point of view|
Dark Room Ambience 2 (as named internally) is the main theme of Norion in Metroid Prime 3: Corruption. It is one of two "Dark Room Ambiences", with the other playing on the G.F.S. Olympus during a power flux. This tense theme plays throughout Norion during the invasion, until the Leviathan is discovered, at which point Hi-Fight begins playing and Samus is racing to the Control Tower to activate the Defense Cannon.
Dark Room Ambience 2 plays again as Samus uses her last ounce of strength to reactivate the cannon. A month after the invasion, the "Heion1" theme heard on the Olympus and in Eastern SkyTown, Elysia replaces this theme through most of Norion. However, it will still play in the area leading up to Generator B, which contains some spent Phazon left over from the invasion.
The theme can be heard here.