I am a "Child of Apollo", meaning that I grew up during the Apollo program. Its influence on everything was positive, and fostered explosive growth in the technologies. You wouldn't be packing a cellular phone without that kick start. It is provable that the space program promotes the general welfare.
Perhaps I am a purist on these things. I hear the Liberals go on about Roosevelt's "saving" the nation through the expansion of the government, Great Society, the EPA, and Social Security and other clear Article 1, Section 8 violations. Their basic counter argument is that look at all the "good" coming from those things. And sure...maybe there are a few bits that are "good" like elderly people having some small income, or "clean water" and so on.
However, at that point of discussion, we have surrendered principle and are effectively arguing that Constitutional violations are ok if they are a net positive in the cost/benefit calculation.