2003 MER Update Week Ending February 15, 2003

This week we put to rest what may have been the worst remaining
problem that stood between us and launch.

This one was looking very nasty for awhile. Back in December, we put
the whole MER-2 rover into a big thermal chamber and took it down to
cold martian temperatures. Almost everything worked right, but one
thing was very, very wrong. When the rover got really cold, the
pictures from one of our two Pancam cameras got bad. In fact, they
were worse than bad, they were terrible. Imagine a TV picture with
static so bad you can barely tell what you’re looking at. That’s what
some of them were like. It only happened in that one camera, and it
went away as soon as we warmed things up a bit. But it was pretty
scary, because we didn’t know what was wrong.

We chased this one for a long time. The breakthrough came a few weeks
ago, when Leo Bister at JPL took a really careful look at the cables
that run to all the cameras at the top of the rover’s mast. Something
just didn’t seem quite right to him, and when he dug into it he
realized that we had built the cable wrong. That cable has a bunch of
pairs of wires in it, with the pairs of them carefully twisted
together. Problem was, the wrong wires had been paired up when they
were twisted, letting signals from the camera become contaminated by
signals in other wires. It was the kind of thing that would get worse
when the cable got cold, and it was also the kind of thing that could
really mess up a picture.

This had to be it, but you can’t be sure until you test. We built
some new cables, replaced the old ones, and late last week we put the
whole rover back into the chamber again, cooled it down, and held our
breath. It worked. Every picture was clean and flawless, even at the
coldest temperature. It was a huge relief, and a nice piece of
detective work by Leo.