I just got back from WDW (say 4 hours ago
) and we had a great time. Mission Space has 2 versions that you can go on, there is the usual one and a less intense one.
The usual ride had you blasting off into space, you feel all of the G forces on lift off and you also have the weightless feeling once in orbit. You should do the ride, DON'T MISS IT! If you are concerned, try the less intense version!
PS, don't go on a full stomach or even worse, an empty one
Hope you have a great trip!