Ask HN: What is it like to work on software for space exploration?

Hi HN! One of the most inspiring presentations I've ever seen is by someone who worked on the code and instrumentation for the Rosetta spacecraft sent to explore the comet Churyumov-Gerasimenko. I still think about this presentation often and wondering how is it really like to write code for spacecrafts and space missions. Has anyone worked on similar projects professionally? Can you share a bit about your experience and the exciting technical challenges? Thanks in advance!