1. Characters
   1. Barton
   2. Gerry
   3. Marilyn
   4. The Captain
2. Themes
   1. Value of human life
   2. Law
   3. Humanity
   4. Nature/Fate
3. Settings
   1. Earth
   2. The frontier of Space
4. Literary devices/Imagery
   1. Data/numbers
   2. The cold void
   3. Dusk on the planet