I haven't read any of the other post on this thread, so sorry if i am repeating what others have said. Withe that being said, What happened this past week was a herific tragedy, and my prars are withe the woman's family. However, I highly doudt that Mission:Space will close any time soon for a few reasons.
1. It has not been determind if the ride itseld birectly caused the womens death. The young boys death was not caused by the ride, but by an enlarged heart.
2. Disney spent 100 million dollars to put this ride together, and i would be a hugh financial blow to just do away with it. So that won't happen.
3. Disney warns people over and over again not to rideif they have any health problems. It's likely the women didn't know she had high blood preasure, and that is nobody's falt. This tragedy was an accident and nobody can be blamed for it. Disney can't test any guest befor they get on the ride, so it is up the individuals to use good judgment and common sense.
In closing, I personally liked M:S, and have to say it is one of Disney's best attractions from a technology view point, and I would hate to see it true. And pray to God that nobody else has to go through what the young boy's and the women's family are going through, especially at a magicak place like WDW.