At a Honolulu stake conference in 1961, Joseph Fielding Smith said,
We will never get a man into space. This earth is man's sphere and it was never intended that he should get away from it. The moon is a superior planet to the earth and it was never intended that man should go there. You can write it down in your books that this will never happen.
Granted that this was before he was the LDS President, but for the LDS to say this isn’t a prophecy because he wasn’t President yet flies in the face of that last sentence!