From a fantastic NPR piece about Apollo 11 astronauts writing on the walls of Columbia:
In both pen and pencil, the astronauts scribbled down flight plans, a series of numbers and notations from mission control, and a calendar. Each day of the Apollo 11 mission is crossed out except for the final day, July 24, when Columbia returned to Earth.
Most sci-fi spaceships are too antiseptic. One of the things I love about Serenity, from Firefly (paid link), is Kaylee’s paintings on the galley walls. Too few SF ships feel real in the way that those little flowers make Serenity feel real.