Ascension is roughly 35GB; a PSP UMD disc holds only 1.8GB.
The game was developed exclusively for the PlayStation 3 to push that console's hardware to its limits. Because the PSP is significantly less powerful than the PS3, a direct ISO "port" or "work" does not exist in a functional capacity for original PSP hardware. Why You Won't Find a Working ISO god of war ascension psp iso work
Re-skinned versions of actual PSP games. Ascension is roughly 35GB; a PSP UMD disc holds only 1