I've never had Tang, so I can't tell you if it's good or not. What I can say is that NASA did not invent Tang. Tang was developed in 1957, a full year before NASA was founded in 1958. Why then is Tang associated with NASA? Tang was used in several early manned space missions in the 1960s. Maybe this is where Tang gets its claim to fame (assuming Tang ever had fame!). It's cool that Tang was used by NASA astronauts, but this is a far cry from NASA inventing Tang.
Now I'm curious what Tang tastes like. Can you buy Tang on Amazon? Yes, yes you can!