Thermal Padding is a suite of garments made out of an advanced insulating material. The garments are able to keep a player from freezing to death in the cold environments of Outer Space. They are also able to keep the player from suffering heat exhaustion in an overly hot environment.
The temperature indicator on the Life Support HUD will show if the player is becoming too hot or too cold - as the temperature approaches dangerous levels, an "Invalid Thermal Protection" warning will be shown. On Mars and the Asteroids, simply wearing a full set of Thermal Padding should be enough to fix this.
The garments are worn underneath the player's armor. They can be equipped using the dedicated slots for them in the Galacticraft player inventory tab, next to the regular armor slots.
Thermal Padding has the interesting property of changing color depending on the environment. In an ambient temperature which is suitable for life (for example, the Overworld) it is mostly green. In a very cold environment, it is mostly an orange/red color (heating mode). In a very hot environment, it is mostly a blue color (cooling mode).