Here is the full list of all 70 Heat Signature achievements.
Start a new galaxy
Talk to Fiasco after liberating every Stronghold
Take someone out with a melee attack less than 0.5 seconds after Sidewinding
Complete a Hijack mission in a Warzone
Completely eliminate a faction from the galaxy
Acquire a keycard while Visiting
Find a unique item
Complete a Pacifist Clause
Cause a guard with a subverted shield to shoot themselves
Kill someone with a Shortblade within 1 second of killing someone with a Longblade
Crash a shield
Reflect a bullet with an emergency shield
Pass through a ship's vision undetected in the Sovereign Coldfire
Complete a Ghost Clause
Board a ship without docking your pod
Cause a guard to shoot themselves by Swapping with them
Complete a theft without being seen or harming anyone
Save someone with the Offworld Angel
Teleport to an airlock with the Glitcher's Tick
Dock at a friendly station while on emergency fuel
Complete an Audacious (or harder) mission
Complete a Mistake mission
Cause a sentry to shoot a guard by subverting it
Complete a Silence Clause
Complete a practice mission
Complete an Enigma Clause
Retire as a Living Legend
Complete your personal mission
Break a ship with the Foundry Brick
Complete a Hard (or harder) mission
Deliver an assassination target alive
Complete a Bloodless Clause
Complete an assassination mission without harming any other crew
Liberate a station
Retire Sader Fiasco
Complete an Assassinate mission without entering the ship
Knock a Capture target through a window
Delete a Galaxy
Catch a Rescue target in your pod while they're suffocating in space
Rescue one of your own characters
Rescue a friend's character
Find an item that belonged to a Steam friend's character
Knock yourself out with a wrench you threw
Use a second Visitor before the first returns you
Be rescued from your captor by the Visitor
Make it to a station after your pod has been destroyed