For Sagan, talking about Mars must be as familiar territory as one's 'back of the hand' to use an old saying. Sagan coveres the history and evolution of our understanding of the Red Planet. All the expected stuff such 'The War of the Worlds' by H. G. Wells to famous Martian canals 'discovered' by Perceval Lowell.
Sagan talks about Robert Goddard and Konstantin Tsiolkovsky. And then the modern age of Martian exploration with the Mariner landings. And what an awesome achievement that is! Audacious and impossible-sounding dreams of a century ago are a banal reality today.
Sagan describes the topography and geology and ecology of Mars — about how it came to be a cold and barren planet in spite of having conditions that are seemingly clement for life to arise. The search for life on Mars continues of course.
I am sure like Sagan that one day we'll be the Martians — and all that that implies. I look forward to unmanned aerial vehicles flying in the thin Martian atmosphere and sending the videos back to planet Earth. Oh, what a fantastic thing that would be!
The ideas of terraforming Mars to make it habitable for humans is also an engineering dream that will surely come to fruition in the due course of time. Again, what awesome ideas! Release the CO2 from underground reservoirs and plant vegetation on the planet and let the atmosphere thicken and an ozone layer envelop.
Then one day, Mars will/might have an atmosphere quite Earth-like and we will be able to roam its surface just as we roam the surface of Earth nonchalantly. I can't say 'I look forward to that day' unfortunately as I will have been safely dead by then.