Out of all 14 missions, there are a total of 70 medals to be earned, 5 per mission.
One Medal each (Mission Complete) will be awarded for completion of the mission alone, one each (Enduring Service Medal) for completing missions without dying, and one each (Efficiency Medal) for completing missions within a certain time limit. The other two medals are mostly connected to optional objectives.
You can earn medals across various playthroughs, so you don’t have to earn all medals in a single session.
Restarting a checkpoint will void the Enduring Service Medal even if you didn't die - I strongly recommend to go for the Story Mode difficulty to also make the time-based medals a breeze.
In certain missions, some medals will give you additional achievements as well.Mission 1: Form the Vanguard
Mission 2: The Skies of Yavin
Mission 3: Through Enemy Lines
Mission 4: Secrets and Spies
Mission 5: The Trail From Desevro
Mission 6: Signal to Noise
Mission 7: Into the Abyss
Mission 8: Fractured Alliance
Mission 9: Chaos at Mon Cala
Mission 10: Terisa's Vengeance
Mission 11: Nowhere to Stand
Mission 12: Rally the New Republic
Mission 13: Fire in the Heart
Mission 14: Last Flight of the Starhawk