Some more info and the reasoning behind design decisions.

Artemis’ quiver is a reworked Artemis’ kbin community icon, but while that icon had 7 arrows for good luck, this one has five — for future five stars in the App Store :)

Stellar siblings is called that because the stars on the background are taken from a region in the night sky that includes the Lyra constellation — one that is associated with Apollo, Artemis’ brother. Larger stars are from the constellation itself, while smaller ones are those visible around the constellation. All the stars are carefully placed using stellar maps, so what you see on the icon should pretty closely resemble what you’d see irl if you can find Lyra.
Icon with stellar map overlaid

And Artebierre is just fun imo :) The name is a nod to Alcubierre drive, the fastest sci-fi-ish FTL drive (to get "to the moon"). Not completely sure about the nebula shape yet, and whether it should have more or less contrast in general.
A previous version and one other icon