Each captain begins his life with 100 max Stamina. This stamina is used up whilst exploring derelicts. Various actions will use various amounts. Over time your stamina will replenish itself to your maximum Stamina limit.
Think of it like the way bio fuel is regenerated over time, the similar principle is true for stamina. Like fuel stamina is recovered every 15 minutes.
Currently 5 Stamina is recovered every 15 minutes. That’s a theoretical maximum of 480 Stamina a day if you were in and playing using stamina all day.
This type of regeneration means you can use up your stamina pool 3 or 4 times a day, every day should you wish.
CE Store Based Stamina Boosters.
There are a range of CE Store based account upgrades and extras to help you with Exploring both Planets and Derelicts. These are of course optional.