Spirit Sol 258

Mars is once more visible from Earth. And we rover planners are back to work.

Thisol's sequence is mostly cut and pasted from previous sols: we're once again taking MI images of the capture and filter magnets (though not as many as we usually do when we do this, since we're downlink-limited thisol), taking another image of the dirt clod stuck to the MB, redoing the MI mosaic over GreenEyes, and finally APXSing the hole we left behind when we pulled up the dirt clod.

The only thing complicated about the sol is putting the APXS on the dirt clod's former home. Normally, we have a terrain mesh that shows our targets, but that's not the case here -- this time, we have only the MI images to go on.

This ought to be easy: we know where we placed the IDD previously, and we can see exactly where the missing soil is relative to that placement. (The MB contact ring, which made the impression, is an O-shape. The resulting impression is a rough semicircle, centered "northwest" of the center of the images). The problem is that I'm not sure of the dimensions of the contact ring, so although I know which direction I want to move the IDD, I'm not sure how far to move it. The documentation I normally use to answer questions like this doesn't tell me, so I start looking around for someone who would know.

This proves to be harder than I expected. The Mobility/IDD guys on shift don't know. Jake Matijevic points me to a book of images, which shows the part I'm interested in but doesn't show scale. Lori Shirashi isn't around, so I call Joe Melko, who doesn't provide an answer.

At last I try asking thisol's MB instrument rep, Iris. She proves to know just enough: she knows the inner diameter of the O. Armed with this, I'm able to go back to the image Jake pointed me to, measure carefully with the ruler built into my trusty Swiss Army knife, and work out the width of the ring itself. (For the record: the inner diameter is 15mm, the ring itself is 10mm wide.)

Which means, since I want to move the arm to the middle of the ring's impression, that I need to move it: 12mm. Thank you, and good night.

Courtesy NASA/JPL-Caltech. An MI of the filter magnet, showing -- yup -- we plopped a chunk of dirt right onto it.

Courtesy NASA/JPL-Caltech. The capture magnet, which we also imaged thisol. I love that manadala-like bullseye pattern.

No comments: