On Wed, 6 Mar 2019 16:59:19 -0800 (PST), RichA
wrote:

Ever dig in soil and hit a rock? Seems NASA didn't expect it. Pretty stupid.

https://www.bbc.com/news/science-environment-47469071

First of all, NASA didn't design this probe. Second, it was entirely
expected that the probe could hit something that would slow it down or
that it couldn't get through. Making the probe retractable and
repositionable was not a practical option.

If you knew anything about engineering, you'd know about design
tradeoffs and cost/benefit analyses.