We live in an age where we have maps of other worlds that almost rival what you use to navigate your way from coffee shop to couch. For a planet like Mars we have robotic explorers sending back daily data (when not interrupted by global dust storms). It is very easy to forget that half a century ago we had none of this.
Before NASA’s Mariner 4 spacecraft made the first successful flyby of Mars in July 1965 we had very rudimentary knowledge about this world.
Take for example a classic paper by Carl Sagan and Paul Swan, published in early 1965 (ahead of the Mariner 4 flyby). This study was titled: “Martian Landing Sites for the Voyager Mission” (note that this was not the same Voyager as later toured the solar system). Here Sagan and Swan discuss a mission strategy already under development that could have used Saturn V’s for launch, and a combination of orbiters and landers that presaged what was eventually done in the Viking missions.
But perhaps the most revealing part of this document is this statement on the first page:
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