There's no flying in atmosphere at all. To do what the parent commenter says would require going back to orbit (loading screen) then choosing a spot on the planet to land (another loading screen). When you land like that on planet, it generates an instance for you that is procedurally generated, but won't contain any of your mission markers. (I haven't actually tried that part, but I've seen others talk about it.)

The game is basically areas, separated by loading screens. You get in your ship, that's a loading screen, you fly to orbit, another loading screen. Then in orbit if you want to go to another planet, you set course and do another loading screen. Once there, you choose a spot and land for another loading screen. There is flying in space, but it's limited to small instances with some other ships, and POIs. Your ship's speed is very slow, and as far as I've been able to tell you cannot walk around your ship while it's in flight (this may be a limitation of the controller controls, I saw a streamer stand up in flight, but I don't know if that was a bug or not. There's no binding to stand up when you are in flight on controller.) I just wasn't holding B long enough, you can stand up when you are in space, you just have to hold the normal binding for longer than I expected.

All that being said, I'm still enjoying the game. But I went in with low expectations.