Data Recorders.

So I discovered that once i finally beat them game (fyi the final boss Nim... that was just dumb and a horrible idea and nothing like the rest of the game) Anyways I have found about 4 data recorders. I found a link on here someone provided http://orcz.com/Defiance:_All_Data_Recorder_Locations and my question is that are these data recorders always there or will you be able to pick them up now that i have finished mostly everything ? Or do you in fact have to pick them up with the associated mission?
Also, I find the time trials impossible and the hotshots quite easy... if anyone finds the reverse we should switch psn id's for a day or two and complete those for each other... because I honestly can't even get a bronze on some of these trials.

There always there AFAIK. Except that one in sausalito where you need to be in the Ranchers and Raiders mission I believe.