Check closer to your trip. Lots of reservations are made "just in case" and are canceled as plans get firmed up. Make the reservations you are happy with, but the month out, the week out, the night before... you'll be surprised what suddenly shows up as available.
But Space 220 isn't worth it. The arrival is cool, but it's over in 5 minutes. And then you find yourself in a pretty sparse restaurant, with a lot of seats at tables that don't have a view of anything, and *very* mediocre food. We went for my birthday, and the seat we had was along the big screen, but were too far toward an end. On DH and my side we could see an astronaut from time to time, but my Dad who was facing us, only saw black and the doorway to the bathrooms. If you can get something in the Lounge that would be a much better value, than the prix fix dining in the main restaurant.