Since 1975 NASA has maintained an annual publication, called Spinoff, that catalogs new commercial technologies with their roots in the manned space program. It is commonly argued that these "spin-offs"—which range from medical devices to firefighting equipment—can justify government expenditures to send humans into space. Many so-called space advocates respond to critics of human spaceflight by pointing out the various gadgets in their home and society that actually can be traced back to NASA. They imply that their critics take advantage of spin-offs but aren't willing to pay the costs to develop them.
Though NASA programs do result in spin-offs, it is absurd to suggest this justifies human exploration of the cosmos. At most, spin-offs could offset a small portion of NASA's budget. If we want to be honest with ourselves, we must face the fact that the government could have directly invested funds to develop artificial limbs, improved car tires, and anti-icing systems for aircraft. It would have cost far less.
Steven Weinberg, an American physicist, has a point when he says "The only technology for which the manned space flight program is well suited is the technology of keeping people alive in space." But I disagree that human spaceflight is a waste of money. If Weinberg doesn't understand the value of it, he never will and there is nothing anyone can do to change that. In an ideal world, those who weren't interested in human exploration wouldn't have to burden the costs—but our society is very far from this ideal in other economic situations. In the mean time, the supporters of human spaceflight must seek rationales other than spin-offs if they want to be taken seriously.