Here is the full list of all 15 Guardian Force - there are Saturn Tribute achievements.
Go on 20 sorties (single player only)
Go on 10 sorties (single player only)
Destroy the final boss (single player only)
Clear all stages (single player only)
Clear stage F at any difficulty (single player only)
Clear stage E at any difficulty (single player only)
Clear stage D at any difficulty (single player only)
Clear stage C at any difficulty (single player only)
Clear stage B at any difficulty (single player only)
Obtain the highest achievement (single player only)
Clear stage A at any difficulty (single player only)
Increase the weapon power to MAX level (single player only)
Clear the Practice Stage (single player only)
Destroy the mid boss within the allotted time (single player only)
First sortie (single player only)