The Final Mission

Twelve-year-old Amelia is the youngest member of crew on the Meddler, a spaceship that salvages scrap metal and anything else of value; currently they are interested in exploiting a debris field near the planet Canus, home to their cabin boy Greeny and his dog-like race, and Amelia is mad because her mother will not let her take part, so she and Greeny stow away on the salvage ship--but not everybody sees this particular debris as free-for-the-taking, and it looks like this may be the Meddler's final mission.