Here is the full list of all 24 Star Hammer: The Vanguard Prophecy achievements worth 1,000 gamerscore.
Destroy a remnant ship in campaign mode
Destroy a nautlid
Destroy an enemy with a missile
Win a skirmish battle
Stun an enemy
Kill an enemy with a laser beam
Recruit the pilot.
Recruit the comms officer.
Recruit the science officer
Recruit the intelligence officer
Protect Novus on your own terms
Uncover the Remnant conspiracy
Protect the shipbuilding yards.
Evacuate civilians from the Boardwalk.
Evacuate workers from DM3
Keep your crew friendly
Destroy 100 nautilids.
Destroy 25 Remnant ships.
Kill a stunned enemy with the Destroyer's laser.
Deploy thirty countermeasures
Have a reinforcement join you in battle
Don't lose a single escort objective during the war
Deploy a fleet group with maximum Command Points
Recruit the engineer