Something along these lines would be fun.
I'm not the greatest designer, but I think you get the idea: a cute rocket with a rainbow trail.
A few other musings:
the rainbow trail reminds me of nyan cat, an animated version in that style might make for a nice loading screen
I looked up "rocket nyan cat" and saw this hamster with a rocket attached: https://static.wikia.nocookie.net/nyancat/images/5/58/RocketHamster.gif/revision/latest?cb=20210923233749
It would be cool if someone could do something similar with a lemming.
That reminds me of Buzz holding Woody with a rocket strapped to his back: https://static.wikia.nocookie.net/bd893090-c6dc-4d2f-96a5-9ec62637242e
It's a similar feeling, with Voyager (and other apps) picking up Apollo and trying to keep it flying.
The word Voyager makes me think of the Daft Punk piece, there's a bit in the video with an anime style star, this could make for a simpler icon theme: https://youtube.com/watch?v=CqZgd6-xQl8&t=2m29s
I think the name "Rocket" would be a cool name for an Apollo inspired app - simple and effective.
The rocket idea could be anthropomorphised (smiley cyclops) and become a character in an of itself; there was an astronaut with Apollo, there could be a rocket character with Voyager.
I looked up Wallace and Gromit's rocket, because I remember really liking the look, but I don't think it translates: https://youtube.com/watch?v=Kb0ooQKbflM&t=2m38s
Orange and Blue is a popular contrasting colour scheme though.
I like the rainbow focus in the brief and I hope to see some cool creations. I'm not precious about the rocket idea, but I hope it inspires some more creative submissions, I definitely think something other than a slight variation on the lemming motif would set this app apart from the rest.
Fantastic. Hopefully this becomes the default and helps to keep your server costs manageable.