Altas were humanoid servants of The System. The two seen were female - others may have existed. They acted under the direct control of The System and may or may not have been androids. If not, they had presumably been subjected to considerable augmentation, allowing direct neural interfacing (by touch) with The System and needed an integral life-support unit: Blake disconnected a line between Alta Two's neck and an abdominally mounted control unit. (B: Redemption)