The NASA JPL News item NASA's InSight Takes Its First Selfie provides a link to the high resolution image PIA22876.

Below I've cropped out the West solar panel array, which shows surprisingly tall vertical ridges that extend the full length of each of the ten segments where it joins adjacent segments.

Are these related to the way the panel unfolds? Do they have a function now that the arrays are fully deployed? I would think they might tend to trap Martian dust blowing in the wind and interfere with any cleaning by subsequent wind or dust-devils, but maybe the effect is just the opposite?

One thing I worry about is what @Uwe had mentioned in comments earlier; that blocking one junction cell in a group of series-connected junctions cells causes a much larger current drop than you might estimate from the fraction of the total area covered. In some wiring configurations small shadows can become big problems and big losses.

As pointed out in comments, these are triple-junction cells, so unlike the old silicon cells that had but one pn junction per cell, these have three, stacked directly on top of each other. https://solaerotech.com/

cropped from PIA22876 InSight's first selfie

For comparison, Martian dust on top of Curiosty, from Have any systems on any Mars rovers failed (even partially) as a result of a dust storm? (besides loss of solar power) cropped from PIA22486

cropped from PIA22486 Curiosity after dust storm

  • $\begingroup$ Collecting dust is indeed troublesome, especially in the middle of the panel of course. I would not have placed solar cells there ! $\endgroup$
    – Cornelis
    Dec 12, 2018 at 13:50
  • $\begingroup$ I wonder if the deployment is repeatable on site. Retracting and deploying again may not remove all the dust, but it may collect it in the mid fold? $\endgroup$
    – user19132
    Dec 12, 2018 at 14:34
  • 1
    $\begingroup$ Honestly, they look purely structural to me, but I don't have any design insight (no pun intended) $\endgroup$
    – Tristan
    Dec 12, 2018 at 15:03
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    $\begingroup$ @qqjkztd The requirements seem to preclude repeated deployments. $\endgroup$
    – called2voyage
    Dec 12, 2018 at 16:06

1 Answer 1


Those are the radial spars that give the solar array rigidity once it's fully deployed.

UltraFlex solar array deployment

Image Source: The Space Technology 8 Mission; S.F. Franklin, et al.

The landing site for InSight was selected to be a low dust environment. Clearing events are not expected during the time of the mission.

As far as I can tell, dust collection was not a consideration in the radial spar design. However, the InSight solar arrays and batteries were designed to ensure enough power could be drawn even in poor conditions.


  • $\begingroup$ Is this the first usage of this style of solar array? $\endgroup$ Dec 15, 2018 at 6:30
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    $\begingroup$ @MagicOctopusUrn No, not even first on Mars. It was used on Phoenix before. $\endgroup$
    – called2voyage
    Dec 15, 2018 at 13:12
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    $\begingroup$ How can I invoke my "authoritative-sounding yet unsourced" rant if you include so many sources? This is one source for every 11 words; one for every 8.6 unique words! $\endgroup$
    – uhoh
    Dec 16, 2018 at 7:35

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