[LINK] Discovery shuttle launch viewed from an airliner

Space flight has military benefits ("Hey look - we can go into space too, so don't fuck with us!"), scientific benefits (experimentation in a zero-gravity vacuum, material analysis of the interplanetary medium, vastly improved telescopy), immense practical benefits (without rocketry we wouldn't have cell phones and GPS devices, for example), and potential long-term benefits (the possibility of space colonies, protecting humanity from extinction due to a variety of existential risks). Since NASA is actually fairly cheap as U.S. government projects go, and since spaceflight is increasingly moving toward becoming a private endeavour (made possible, in part, by decades of publicly-funded spaceflight) you'd be hard-pressed to demonstrate that the cost-benefit analysis comes out in the negative.

EDIT: That's also not including the quality-of-life benefits that come from getting to watch something this totally awesome.

The primary benefit to say the Apollo program in the 60's and NASA from its creating up to the late 70s was status signalling. Thinking of other ways to signal status and pre-eminence in that time period I have a hard time thinking of something that would do as much with such a small investment.

Decisively winning the war in Vietnam might come close. But I need to look for the figures of what the RL Vietnam war cost. In any case comparing the cost in lives (including indirect ones) the cost is probably ridiculously smaller.

I think we will see future manned flight to the Moon for the same reason. The propaganda impact per unit of currency of hundreds of millions of people watching the American 1969 Moon landings on black and white television receivers might not be that much bigger than billions of people watching the Chinese moon landings in 2029 in HD, especially since with a 50+ year gap younger people will not have a comparable "grand technological gesture" in their memories. Also for a government like that of the Chinese its probably significantly cheaper to do it today than in the 60s, this is compounded by the fact that they have a oversupply of young male high IQ engineers and scientists.

Think of the NASA of the 80s and 90s as a retirement plan for high IQ experts too old to be retrained to do other tasks.

it only counts as rational if the benefits exceed the costs.

True, but that applies to everything, not just things that are conspicuously interesting to "geeks".