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

[djellison]

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?

I've looked at every single MER image taken from Sol 1 to present sol - and I've NEVER noticed that. Good catch. I never ever stop learning stuff from this place.

[nprev]

No kidding it's a good catch!

Man, just goes to show you: No two spacecraft are ever completely alike.

This is sort of a puzzling difference, though. I can't imagine what the reason for it might be, intentional or otherwise.

[Reckless]

I used to go by the cable bent around the base of Spirits sundial,

Roy

[James Sorenson]

I have noticed this, as well as the white ring that has warped up on Opportunity. I Just sent Jim Bell an email about these two differences along with this image I assembled in hopes of an explaination.

 MERAB_Caltarg_comp_L234567.tif ( 741.34K ) Number of downloads: 579

[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!).

[tasp]

It appears the rovers have lasted long enough to become Martian LDEFs.

There might be some relevant materials science to be done here for the benefit of subsequent missions. These missions just can't stop giving, can they!

[eoincampbell]

... to become Martian LDEFs.

What are those, again ?

[nprev]

LDEF= Long Duration Exposure Facility.

[PDP8E]

..wasn't sure where to put this but it meshes with James Sorenson's info from Jim Bell and the observation that he rovers are also LDEFs now. It is an animation of the RTV warping process on Oppy's sundial.

I just noticed in this quicky that I left off the Sol numbers (!)
(the list I worked with are 565, 585, 594,600, 604, 607, 634, 657, 689, 713, 802, 918, 1500, 2273)



Cheers

[tasp]

Thanks for that. Interesting to see the physical deterioration wrought by the alien environment with the magic of time lapse. Wish my car was holding up as well as the rovers (except for the seized wheel thing).


I wonder if the chlorides, sulfates, peroxides, and just plain old 'grit' are slowly chewing up the exposed 'innards' out of camera view?

[nprev]

The grit...yeah, maybe, esp. any of that hyperfine sand around moving junctures. It could even chew up wire bundles that experience any sort of vibration or repetitive motion, though I don't think the MERs ever produce enough of that to make that a significant concern.

The sulfates, chlorides, etc....doubt they're doing anything nasty. Unless I'm completely wrong here, I think that those substances have to be in an aqueous solution to react with metals or other materials & there's certainly been no liquid water on either rover, not even morning dew, and what water vapor there is in the air is extremely sparse. (Don't think that the occasional frost would do much.)

[djellison]

Internals? Doubt it. A bit of a polish to the exterior of the camera? Maybe. The wheels are certainly scuffed compared to what they were when new.