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