Jokes aside, russian space program had some AMAZING developers working in some very low-level languages with unbelievable efficiency. I had the pleasure of working with some of them many years later on enterprise software at large banks.
NASA has written some amazing software as well. Start here: https://news.ycombinator.com/item?id=8063192
Also, check this out: http://www.fastcompany.com/28121/they-write-right-stuff
Very different from how a typical Node.js left pad module is implemented.
There's a reason RTOSs don't have very tall software stacks with multiple layers and virtual machines between them and the hardware.
When your garbage collector invoking at the wrong millisecond 0.01% of the time means everyone on the craft is incinerated in the atmosphere... that's a different level of reliability requirement.
Remember we had an entire game industry, graphical assets and all, distributed on 1.44MB floppy disks.
(In the latter case, not everything was written in assembler but it was all compiled.)
Early on, many space data systems used wire core memory to reduce errors.