Although the scene over the credits is ostensibly showing the future of space travel (and providing a roll call for all the film's key actors), it's actually doing something much more human; showing how every character moves on from the high-pressure rescue. Lewis lives at home with her husband (probably listening to ABBA). Johanssen and Beck are now an item and have (conveniently) had a child during the launch. Martinez is heading back into space. Montrose is the key spokesperson of NASA. Mindy Park has gone from rookie satellite operator to a key part of Mission Control. What the film aims to highlight, over the simple fact of the character's moving on, is that they've started entirely new, often opposite chapters in their life. Martinez struggled with the decision to mutiny for family reasons, yet is now jetting back off on another several-hundred-Sol mission. The relationship between Beth and Chris was downplayed, presumably out of a mutual desire to remain professional, but has now come to fruition. We don't know much about Lewis' past, but her military history suggests a very active life, making her settling down a major change. It's a small, but rather beautiful end-note. Just as the rules of space travel has changed, so too have the goals and meanings of the character's lives. The point is that while the whole Watney rescue had a profound impact on all involved, it was just part of their bigger picture. Nowhere is this better shown than with the one key character missing from the epilogue...
