The Martian is a film about isolation, survival, hope, and the realities of space. Mark is left behind on Mars when his crew believes him to be dead. In fact, he is alive, but the stakes become immediately higher as going to and from Mars is not flying from New York to Hong Kong. We watch as Mark, who is a botanist, begins to do everything he can to survive. The importance of this for the audience is that we always have a choice when we are wounded and seemingly isolated and left for dead; we either get to work doing what we can with what we've got or we don't. However, being inert cannot be an option. Mark has been trained for this and we can see that his background in botany is useful for his survival in his attempt to grow more potatoes for his long wait for a ride home.
The use of the video diary in the film is an important facet of Mark's ability to remain on course for survival. Why? Because it allows him to maintain his daily assignments as if it were business as usual, and for us as the audience to experience these moments allows us to, at time, peer beneath the surface of what is going on in Mark. We see his frustrations, excitement, wins, we glimpse into his fears and his hope. It allows an avenue for Mark's character to relate to the audience emotionally.
It's important to also note the decision of the Hermes crew to turn back towards Mars to rescue Mark. NASA head Sanders has already vetoed the plan, but Henderson bypasses chain of command and puts the choice in the hands of the crew which he knows will not abandon their own. The film while set in the vastness of space upon a distant planet is primarily about the choice to save the one even at great risk to more. The story reflects the idea that every life matters and deserves the honor to be fought for, and that is what the Hermes crew does. They choose to fight for their comrade and their friend and bring him home.
