Ascretta is a planet that used to act as a presumed Lantean guidepost installation.
At some point in the past, a curator for the Satedan City Museum searched the presumed Ancient guidepost on Ascretta and discovered a ZPM, very faintly glowing within. The curator would then take the ZPM back to Sateda where it was stored within the museum's archives.
In 2009, Doctor William Lynn found a reference to a ZPM in the museum catalogue and had Ronon Dex translate the reference. Through this reference, they discovered the existence of a ZPM on Sateda and eventually managed to recover it. After examining it, Doctor Radek Zelenka determines that the Ascretta ZPM only had minimal power left, barely enough to launch a few drones or raise Atlantis' shield for a few minutes. (SGA: "Allegiance")