This is an entire list of missions that you can find by scanning a planet or locating an item. Do any five of these missions from the list for the achievement to unlock. You do not have to do all five in one campaign. Multiple playthroughs still count towards this achievement.
Cluster -- System -- Planet -- Mission Name -- Found/Scan
Caleston Rift -- Solveig -- Sinmara -- Endangered Research Station -- Scanned
Caleston Rift -- Talava -- Taitus -- Mining The Canyon -- Scanned
Crescent Nebula -- Lusarn -- Tarith -- Blood Pack Communications Relay -- Complete Patriarch and Deliver Datapad assignments for Aria on Omega
Crescent Nebula -- Zelene -- Helyme -- Captured Mining Facility -- Scanned
Eagle Nebula -- Amun -- Neith -- Wrecked Merchant Freighter -- Scanned
Eagle Nebula -- Strabo -- Jarrahe Station -- Abandoned Research Station -- After Neith
Hourglass Nebula -- Faryar -- Daratar -- Eclipse Smuggling Depot -- Scanned
Hourglass Nebula -- Ploitari -- Zanethu -- Estevanico -- Scanned
Minos Wasteland -- Fortis -- Aequitas -- Abandoned Mine -- Scanned
Omega Nebula -- Arinlarkan -- MSV Strontium Mule -- MSV Strontium Mule -- After Joab
Omega Nebula -- Fathar -- Lorek -- Lost Operative -- Emailed to you
Pylos Nebula -- Dirada -- Canalus -- Anomalous Weather Detected -- Scanned
Rosetta Nebula -- Enoch -- Joab -- Archeological Dig Site -- Scanned
The Shirke Abyssal -- Xe Cha -- Zada Ban -- Blood Pack Base -- After Tarith
Sigurd's Cradle -- Decoris -- Sanctum -- Blue Suns Base -- After MSV Strontium Mule
Sigurd's Cradle -- Skepsis -- Franklin -- Javelin Launch -- Emailed to you
Titan Nebula -- Haskins -- Capek -- Hahne-Kedar Facility -- After Jarrahe Station
Das Kuhnen points out that any DLC missions that pop up (i.e. the Normandy Crash Site and Firewalker Missions) count towards this achievement as well.