How do you go into space on Pokemon emerald?

You can't go into space in Pokemon Emerald. There's no space exploration feature in the game.

It's possible you're thinking of a different Pokemon game or another media. Perhaps you were thinking about:

* Pokemon Mystery Dungeon: Some entries in the Mystery Dungeon series allow you to visit the "Celestial Tower," a tall structure that reaches into the sky, potentially giving a similar feel to space.

* Space-themed Pokemon fan games: There are a lot of fan-made Pokemon games. Some may have features involving space travel.

* A different franchise altogether: Maybe you're thinking of a different game or series with space exploration!

Let me know if you can provide more details about what you're looking for, and I can help you further!