You are going away, to some place isolated… in space, of course. You will only be around one other person. You can take an allotment if 1GB of personal media with you (text, video, music, games, pics, etc.) that you will be able to access in your free time indefinitely at will.
The other person will also take 1GB with them, but you won’t be able to talk to them until you’re on the journey.
You will have access to any knowledge resources to perform your function and keep you alive. You will never return to a point where you can get new external media. Any additional media you ever access would have to be created by you and or your travel partner with what you have access to.
You will also not know the sex of your partner, but they have willingly taken the same risks to embark on the journey as yourself, and will have a similar mission.
English Wikipedia is about 22gb without media.
That’s compressed, and plain text compress very well.
For my master’s final project I downloaded the English Wikipedia and after unzipping it grew quite large. I don’t remember the total size, also it was 2018, it will be larger now.