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