QUESTION:
How long into the Probe descent until the FIRST instrument malfunctioned,
and when did the LAST instrument fail (destruction)?

ANSWER from Charlie Sobeck on February 23, 1996:
I hate to be evasive, but it's not really that clear.  It depends on the
definition of instrument failure.  I haven't yet had a chance to see if any
instrument actually quit drawing current by the end of the mission, but
clearly most instruments were no longer returning any useful data.  By the
time the data transmission ceased, the Probe was at a pressure level of about
22 bars.  The Helium Abundance Detector was only designed to work to about 10
bars and had completed its mission at that point.  Although it remained on, it
was not providing any new data.  Similarly, the Nephelometer and the Net Flux
Radiometer data deteriorated (that is, the measured signals were too low to be
useful) somewhere below the 10 bar point, although they, too, remained on and
continued to function.  The Neutral Mass Spectrometer and the Lightning and
Radio Emissions Detector continued to return valid data for much longer, but
also stopped before the communications link.  The only instrument still
providing truly valid science data at the time the telemetry link was lost was
the Atmosphere Structure Instrument, which was still returning the
temperature, pressure and acceleration readings.  Determining exactly where
each of the instruments really lost their science value will be the job of the
investigators, who will surely use remarkable ingenuity to squeeze out the
very last bit of useful data.

But as to when the instruments truly failed, in the sense of blowing a
fuse or being crushed, I can't say right now.  I have the data in hand
and spent all week working on the processing of it.
I hope I can have this answer soon.  But no guaranties.


FOLLOWUP from Charlie Sobeck on March 2, 1996:
I've had a chance to look over the data now, and although as I mentioned
earlier, several instruments *failed* in the sense that they stopped
generating useful data before the telemetry link was lost, none of the
instruments actually quit drawing current by blowing a fuse or melting away.