In "Rocket Summer" to "The Third Expedition," various people try to make it on Mars—and fail. If this were a classic myth (which it kind of is), this would be the part where the hero (Humanity!) sets off on an adventure.
Strangers Come to Town
In "—And The Moon Be Still As Bright" to "The Martian," people settle on Mars—and sort of succeed. In a classic myth structure, this would be the bulk of the adventures.
And Then Everyone Leaves
From "The Luggage Store" to "There Will Come Soft Rains," although people want to settle down on Mars (which is one common end to a classic myth structure), they end up returning home to Earth (which is the other common end).
Then there's "The Million-Year Picnic," which is sort of a final coda or epilogue at the end: although everything is pretty terrible for everyone else, there's still some hope on Mars.