Forum:Help in ME1

hi everyone.I have just started my first playthrough in ME1 and i need help.During the mission (Feros:geth attack) i completed the main mission but my decryption skill was too low to unlock any of the assignments.,and i read in the official guide that the colony will perish if i don't do them.So,my question is:Can i complete the assignments later?or do i have to start from an earlier save?