My condolences! I had a similar experience recently. I was making my way back to the Bubble from Colonia via my first trip to Sag A*. I got to neutron-hopping, and everything was going fine. Then, only 4000 light-years from the Bubble, I slipped up. I jumped into a regular star-system where only 3 other stars were reachable—and none of them were neutron stars. I needed a grade 3 boost and didn't have the polonium to make it happen. I sent out the rat-signal, but even the venerable Fuel Rats couldn’t find a source of polonium that was reachable from where I was stranded. In the end, there was no choice but self-destruct, sending me back to Colonia with all that exploration data *poof* into the wind.
So I will have to start the journey back to the Bubble soon if I ever want to engineer my ship—on the bright side, I got to see asteroid bases for the first time, and I got to participate in the bounty hunting CG!
I was very worried that this setback would depress me to the point of not wanting to pick up the game again, at least for a while. It’s amazing how I've shaken it off. I think this is a testament to how much fun Elite is, that even when your mistakes cost you all this investment of effort, all you need to do is switch things up for a little while. I’m glad I took the time to bounty-hunt for a bit instead of just starting back for the Bubble immediately. Now I’ve cooled off, and I’m actually looking forward to venturing back out to the black again.
Good luck with your next journey, Lunchmonkey, wherever that may take you!