I would go further... This project gives a rare opportunity for a young engineer to learn to build truly mission critical, resilient software while requiring complete, top to bottom understanding of the software and hardware stack.
Even all that to the side, it lets you say you worked on the Voyager project!
I am no longer a junior, but would have been upset to be tasked with refreshing the old historical obsolete laundry (no matter how sacred or distinguished), expecially when I already had experience delivering safety critical products packing much more modern technologies.
The opportunity they would be offering is not rare at all! The opportunity to research and design something truly new on the other way is very scarce.