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Old March 9th 19, 08:59 AM posted to sci.astro.amateur
Quadibloc
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Default NASA never expected to have to re-position its drilling probe?

On Saturday, March 9, 2019 at 12:53:01 AM UTC-7, Quadibloc wrote:
On Thursday, March 7, 2019 at 7:22:04 AM UTC-7, Chris L Peterson wrote:

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.


A naive person such as myself - and such as any number of Congressmen - would
have thought that given that it costs billions of dollars to send a probe to
Mars, and if drilling beneath the Martian surface was an important part of that
probe's science mission, then any extra cost to make "the probe retractable and
repositionable" would have been not merely well worth it, but imperative.

Now, if that probe instead was simply a *minor* part of the probe, tacked on at
the last minute, then that it wouldn't have the volume or weight budget to do
anything but drill once wherever it's stuck *would* be reasonable. I don't know
which is the case, so I'm not prepared to castigate NASA at this point - but I'm
not prepared to exonerate them either.


Having read the article, I see the situation is not as bad as all that.

1) Apparently the probe's design is such that it has a good chance of pushing
this second rock it has encountered out of the way given plenty of hammering
time, and so this may be attempted later.

2) The probe is only meant to measure the subsurface temperature of Mars; it
isn't intended to pick up a core sample for a sample return mission or something
else of similarly critical importance.

3) It has already penetrated to a sufficient depth that it can perform the
temperature measurements needed for at least the earlier parts of the experiment
for which it was designed.

Thus I am now quite prepared to accept that the limitations of the probe are
reasonable as a cost-benefit tradeoff.

John Savard