It is worth returning, one more time, to the Planetary Flight Handbook, because it represents something specific about the kind of contribution that technical handbooks make to the history of engineering.

Technical handbooks are not glamorous.

They do not carry the narrative weight of a mission, a spacecraft, a famous photograph.

They are not commemorated on postage stamps or in movies.

They are reference documents — tools for engineers, addressed to specific technical problems, designed to be used rather than read.

But technical handbooks are the infrastructure of engineering knowledge.

They are where the calculations that have been worked out get codified in forms that other engineers can use.

They are where the methodologies that have been developed through years of specific project work get translated into general frameworks that can be applied to new problems.