Primary Pioneer Group
From Halopedia, the Halo wiki
The Primary Pioneer Group is a possible Forerunner Naval unit that searches for habitable planets. [1] Advance Survey Team-Alpha is probably a smaller group of the Pioneers. Primary Pioneer Group was sent to G617 g1 to observe the ecosystem of the planet, and it was there they encountered the Flood. Advance Survey Team-Alpha was sent shortly after to investigate their disappearance.
