I'm going to disagree with the previous posters. I love rollercoasters - the more drops, corkscrews and upside loops the better ESPECIALLY if it's in the dark and I can't see what's coming (like RNR)! I love BTMR and can ride Screamin' over and over again with no problems. However, I can't handle rides that just go round and round, so Space and Matterhorn that just spiral down are both a no go for me unless I've taken motion sickness tablets.
If it is just the darkness of Space that makes you sick though, you should be fine on Matterhorn.