How can I combine this?
More Planets - Galacticraft Add-on
Galaxy Space [Addon for GalactiCraft]
Planet Progression api
Space Ambient [Addon for GalactiCraft]
Galacticraft Addon - Moon Of Mining
Space Research [Addon for Galacticraft3]
You can't - some of these are only available for 1.7.10 - others are only available for 1.12.2
If you want to play modpacks related to space exploration then check for
Space Astronomy: https://www.curseforge.com/minecraft/modpacks/space-astronomy
Lapitos GalactiCraft: https://www.curseforge.com/minecraft/modpacks/lapitos-galacticraft
You can use a third party app like CurseForge or MuiltiMC to create modpacks. Once you create the Profile for a specific MC version, the apps will show you the mods available for that version.
As TileEntity said, you cannot mix mod versions.
"We live on a placid island of ignorance in the midst of black seas of infinity, and it was not meant that we should voyage far."
Zollern Galaxy is available for 1.7.10 as well as 1.12.2, but I strongly recommend the latter!
Owner and developer of Zollern Galaxy, an add-on mod for Galacticraft.
"The wolf never loses his hunger."