Quoting Fred Brooks (of The Mythical Man-Month fame), Rose said "software is invisible". To make software more visible, you need to know what it is doing, he said, which means creating "metrics on everything you can think of". With a rocket, you can't just connect via JTAG and "fire up gdb", so the software needs to keep track of what it is doing. Those metrics should cover areas like performance, network utilization, CPU load, and so on.
Good advice here, even if you aren't building spacecraft.