The_-Galaxy

This modpack is a pack about space exploration and technology.

Some of the big/main mods in here include:

HBM’s Nuclear Tech Mod

Thermal Series(the mods in the thermal foundation series)

Mekanism

Flans mod

The main mod though is HBM’s Nuclear Tech Mod
It allows you to travel to different moons in the solar system and I am pretty sure planets as well.
It allows brings a lot of nuclear technology to the game including but not limited to fusion reactors, RBMK reactors, DMC, particle accelerators, etc.
I recommend using the wiki for the mod though as it is pretty difficult if you do not know what to do: https://nucleartech.wiki/wiki/Main_Page

This is indeed another modpack of mine for a private server but you are welcome to use this pack yourself. If for whatever reason you want to use it in a video or on a server I not only approve but encourage that you do.