MER Magnets Options

[PDP8E]

Here is a recent image of Opportunity's 'sweep magnet' located next to the Bill Nye's sundial
This magnet has a powerful circular field and a center with no field. In addition to what the magnet captures, non-magnetic particles that are found in the center would be an object of study. This color image was taken on Sol 2273. I had to tweak the colors up just a little since it seemed to be washed out.



Did you know that if some one shows you a random picture of either sundial from Spirit or Opportunity you can instantly tell which is which?



Look at the orientation of the sweep magnets.



(EDIT: or as others have pointed out: the bent wire around spirit's base )


Cheers

[James Sorenson]

This is what Jim had to say about the sweep magnet:

There is no scientific reason why the capture magnets on the two rovers are oriented differently. Rather, it is simply a manifestation of very slight differences in the threading depth of the fasteners for the two magnets and very slight differences in the degree of torque that was applied by the technicians who installed them on the rovers. They just ended up getting secured at slightly different angles.

And his remark on the warped ring on the sundial:

Regarding the obvious "lip" on the Opportunity Pancam cal target's silicone RTV grayscale rings--we don't know why that has occurred. Again, however, there are slight differences between the way the adhesive was applied to the bottoms of the rings (the three rings are separate annuli of colored RTV), and of course as you note, there are differences in the temperature and humidity conditions between the two rover sites (Opportunity has gotten slightly warmer in the summertime than Spirit has, due to its more equatorial location). The rings don't appear (to me at least) to be falling off or delaminating, so perhaps it was a one-time or one-season event involving the loss of strength in the adhesive. Ultimately, who knows. Despite getting dusty (and cleaned, and dusty) and warped, the cal targets continue to be very important for the team for tactical-timescale calibration of Pancam multispectral images (and at a "cost" of only about 2.5% of the data volume on each rover, despite the tens of thousands of cal target images!).