MER Status Report Week Ending March 22, 2003

We’ve just been through two of the toughest weeks we’ve had in the
past couple of years.

Problem number one was with our Moessbauer spectrometer. Each
Moessbauer instrument is like four instruments in one… four
separate sensors that each return data. When we got them to Florida,
the MER-1 Moessbauer looked fine, but one of the four sensors on the
MER-2 Moessbauer had gone totally dead. We spent almost a week
troubleshooting it, and we finally traced the problem to one tiny
electronic part, called a resistor, that had failed. We managed to
figure out why it failed, and we confirmed that the problem
shouldn’t affect any of the other sensors. Roberta Cerda flew out
from JPL, put the broken hardware under a microscope, and fixed it.
She is a true artist with a soldering iron, and the instrument is
now ready to go.

Problem number two was with our APXS instrument, and this one looked
even worse. Six hours into a test at JPL, the MER-1 APXS just plain
died. Or at least it sure looked like it had. It suddenly stopped
working, and when we made some quick measurements it was clear that
a short circuit had developed somewhere inside the instrument. That
kind of thing can be fatal for flight hardware, and most of us were
pretty convinced we were going to have to fly one of our spare
instruments. But Ralf Gellert didn’t give up on it. He took the
instrument apart, and he found the problem. A tiny sliver of
aluminum, probably stripped from a small screw, had gotten wedged in
just the wrong part of the instrument and caused the short. That’s
why we do tests, to find that kind of problem. The instrument wasn’t
damaged, and when he took the sliver out everything started working
fine again. You can bet we inspected the inside of the instrument
really carefully to make sure there was nothing else like that
inside it! So that one’s ready to go too.

When problems like this happen a year or two before launch, it can
be easy enough to deal with them. But when they happen now, with
both spacecraft at Cape Canaveral, it’s a different story. We really
dodged a couple of bullets this week.

Ten weeks to go…