Source: https://ntrs.nasa.gov/api/citations/19730015241/downloads/19...
HTML: https://lettersofnote.com/2012/08/06/why-explore-space/
"Space flight, without any doubt, is playing exactly this role. The voyage to Mars will certainly not be a direct source of food for the hungry. However, it will lead to so many new technologies and capabilities that the spinoffs from this project alone will be worth many times the cost of its implementation."