A number of years ago, the Chicago Semi-Pro Musica (okay, a buncha science fiction fans including author Phyllis Eisenstein) turned themselves into the 'Great Noreascon One-Shot Chorale' for a guest appearance. The director's husband, also Mark (little grey cell lapse here) composed 4part harmony for Green Hills of Earth - with Bob Heinlein's permission (so you know this was a while back).
Yes, I still have it. Hmmm, a research project.

Mark also composed music for some really deathless ditties...including one from India on "The Passing of Queen Victoria", composed as an exercise in doing everything "wrong"...phrasing, accents, high notes, etc.
Of course, what can you do with words like "dust to dust, and ashes to ashes, into her tomb the Great Queen dashes"?