Mars Exploration Rovers Update
21 Oct 2002
(Source: Cornell University)
Athena Mars Exploration Rovers Page (Cornell University)
Week Ending October 19, 2002
We're definitely in the troubleshooting phase of the project right now, and for the last couple of weeks annoying little troubles seem to be popping up faster than we can shoot them down. We're making progress on the step-and-settle problem that came up last week, but we still haven't solved it yet. And this week a new problem came up on the M?ssbauer Spectrometer that we haven't figured out at all.
This is a weird one. The Moessbauer has four different "channels": it's sort of like four instruments rolled into one. When we use it by itself, all four channels work beautifully. But when we hook it up to the rover, only one channel works right. The other three don't, and that means that we get only one-fourth as much good data as we should.
In principle we can "fix" the problem by changing some software, but we're not real comfortable with that, at least for now. We don't understand yet what's causing the problem, and using a quick-and-dirty solution to fix a problem you don't understand is rarely the right thing to do. So we're going to test one idea, and then test another, and keep testing until we get it figured out for real.
It just gets like this sometimes, and when it does you have to remind yourself that none of these problems are major and all of them have solutions. Still, it'll feel good once we've got this batch of problems behind us.
Week Ending October 12, 2002
The MER rovers are fiendishly complicated machines, and literally thousands of things are going to have to go right for this mission to work. All of them have to be tested, and it's pretty common for things not to work right on the first try. This past week, we've been troubleshooting our "step and settle" problem.
The Mini-TES instrument sits at the bottom of a big piece of hardware called the Pancam Mast Assembly, or PMA. Mini-TES looks up the inside of the PMA tube, using it like a periscope to view the scene around the rover. There are mirrors at the top of the PMA, just like in a periscope, and one of them is supposed to move very quickly as the Mini-TES shifts its gaze from one spot to the next. The time this mirror has to "step and settle" -- to move and then settle down so that it's motionless -- is just two tenths of a second. And right now it's taking a good deal longer than that. If the mirror is still moving when Mini-TES is trying to look out at the world, we get a blurry view and bad data.
The problem seems to be that we're not giving the motor that moves the mirror enough juice, so we're going to change that and try it again. We'll see how it goes. But it's just one of thousands of things we've got to get right before we can take these things to the launch pad.