the security missions should be repeatable. At least the mining was for me.
And if you want to find Scord, Find public fleets that are mining, But beware. The belts go Fast, I was in a fleet on my first day of mining, and the belt was killed of Scord before the Orca could finish his first cycle of boosts. LOTS of multis are doing this and continue till all the scord is gone, only to start over after downtime the next day