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