There's no deoxys in Pokemon black or white. You won't get access to Deoxys in-game like some other legendaries like Rayquaza or Groudon. Also, the Space Station in Mossdeep City has got nothing to with getting to Deoxys.
You got to go to a Nintendo Event. Sadly, however, very rarely would you see a Nintendo Event that's targeted for those who play the GBA games. Since the new Generation is much more popular and in-demand,you have less chance of finding such Event.
And another thing: You can only get to Deoxys(Nintendo Event) in Pokemons Fire Red/ Leaf Green and Emerald. You cannot capture it in Pokemon Rby/ Sapphire version. To get it, just trade from any FR/LG/E games that has a Deoxys.