Trope-a-Day: Human Resources
Human Resources: In space, where roughly 3/5ths of everyone lives, no-one wastes precious water, carbon, and complex organic compounds; therefore, yes, bodies are hereby committed to the recycling tanks. Of course, the bodies have to have died naturally first, which should make it marginally less creepy.
There used to be organ donation, too, but these days they just clone spare organs on-demand.