MER 2003 Rovers Status Report Week Ending October 26, 2002

Good news: We seem to have solved the “step-and-settle” problem
that’s been giving us fits for several weeks. The trouble here was
that the mirror at the top of our mast didn’t seem to be moving
quickly enough. Our Mini-TES instrument is supposed to tell the
mirror what to do. When Mini-TES is ready for the mirror to move, it
sends out a signal that means “okay, I’m done taking data for a
little while… go ahead and move the mirror.” The mirror has two
tenths of a second to get to its new position. Mini-TES then sends
out a second, different message that says “okay, you’d better be done
moving the mirror, because I’m going to start taking data again.” And
it starts to collect data, assuming that the mirror has stopped
moving.

What we thought was going on was that the mirror was moving too
slowly, making the data blurry because it was still moving when Mini-
TES started to collect data. But what was really going on was that
the mirror was ignoring the first message completely, and starting to
move when it got the second message! That’ll pretty much guarantee
that you’re going to get blurry data, no matter how fast you move the
mirror.

We were afraid for a little while that this would be a nasty problem
to fix, but Jason Gates found a very elegant solution that involved
just putting a couple of tiny “haywires” onto one of the rover’s
electronics boards. We still have a little more testing to do, but it
looks like one of our unpleasant problems has now been found and
fixed.