No such thing. And I mean a few things:
1. If you’ve been to a place before, it’s technically possible to load up the starmap while planetside, select where you want to go, and just fast travel there.
What I’m saying is, go to your ship, launch it into orbit, bring up the starmap, travel to the orbit of the planet you’re going to, and then land.
If you do it that way you have two chances of random space encounters, one in the orbit of the planet you’re on and one in the orbit of the planet you’re going to.
Technically you have three chances, as there’s a possibility that your space travel from orbit to orbit will get interrupted by a distress call, but a) those are very rare, and b) I think they’re probably also possible when fast traveling from the planet surface.
2. When traveling to a system far away, you could maybe do it in one jump (depends on how good your ship is) but I always break it up into at least two, usually three or four. Each time you jump, you have the chance to encounter someone or something. Sometimes I just jump around to different systems just to see what I might run into.
3. When you’re in a star system, either when you’ve just arrived or before you’re about to leave, have a look at the starmap. There will often be icons signifying different encounters. Maybe a sensor contact, or a ship, or some hostile activity. Whatever it is represents another chance of exploration.
Some of my favourite experiences have been encountered this way. In fact, I’d say running into Juno is number one, and I wouldn’t have done that had I not explored by ship. I won’t say more than that, if you know, you know. But I really liked it.