Outside my depth but I'll give it a stab. Identify what data is important, (is the full 42Tb needed?). Can the data be split into easier to handle chunks?
If it is, then I personally do an initial sneakernet to get the fist set of data over. Then mirror different on a regular basis.
Reddit: open /r/pics or else. Mods: OK but you didn't say how (old.reddit.com)
I honestly don't know if this is allowed here but I thought this is malicious compliance at its finest....
You can have any superpower, but the first person to reply chooses a side effect
self-explanatory!!
3-2-1 Backup Rule (www.starwindsoftware.com)
Something i haven't seen posted here yet, but worth say over and over again....