Also, for all intents and purposes, the code driving these things are running in...

jmcqk6 on Feb 23, 2021 | parent | context | favorite | on: Perseverance rover’s descent and touchdown on Mars...

Also, for all intents and purposes, the code driving these things are running in production for the first time. Of course they can do software updates now that it's on the ground. But the EDL code only gets one shot to run correctly.