This trophy is for reaching the maximum milestone level of 10 for survival on an extreme planet. As of the current patch, this means you need to be on an extreme planet outside of a shelter or your ship for a total of 32 Sols (or about 8 hours). This is a cumulative total that will accumulate each time you are on an extreme planet.
Planets can be extreme either because of Aggressive Sentinels or Extreme Weather. It is much easier to find extreme sentinel planets because they are marked as such whenever you scan a planet from space.
The easiest way to complete this is to land on an extreme planet and immediately use the terrain manipulator to dig a small cave with a narrow opening down below the surface. Sentinels should not be able to find you in such a cave and weather will not affect you while you are underground. If you don't move, you won't consume life support power, so all you have to do is leave the game on for 8 hours and the trophy will unlock.
It might be a good idea to check in every once in a while and save using a mobile save beacon just in case, because at least for me, the game tends to crash every so often.