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The BBC News item 'Rosalind Franklin' Mars rover assembly completed contains a short video, and I show some screen shots below.

It looks like the panels unfold twice, from two stacks of three, to six final panels.

In the question Curiosity is still dirty! How will the ExoMARS Rover keep its solar panels dust-free and collecting sufficient power? I've expressed concern that the solar-powered rover could be seriously impacted by a layer of dust on the panels deposited during a storm, and show some images to convey the issue.

What is InSight's one-sol energy budget on a good day? also shows a before/after dust storm selfie GIF of Mars InSight lander.

Now I'm wondering if these panels can tilt again after deployment, in order to shake some of the dust off if it accumulates to an unacceptable level.

enter image description here enter image description here

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    $\begingroup$ interesting and slightly related question: Will the Mars helicopter be able to remove the dust from solar panels? $\endgroup$
    – uhoh
    Aug 28, 2019 at 2:57
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    $\begingroup$ How is this question different from the question space.stackexchange.com/q/18262/12102 you cited? $\endgroup$
    – DrSheldon
    Aug 28, 2019 at 3:01
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    $\begingroup$ @DrSheldon because it's a different question, that's how. If the answer to this question about tilting panels turns out to be "yes", and if and only if this is the only method to clear the panels of dust, then that question can be marked as duplicate of this. If not, then the questions are unrelated. Until some answers start appearing though, they are not the same question. $\endgroup$
    – uhoh
    Aug 28, 2019 at 3:08
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    $\begingroup$ I really looks like they unfold twice, and at this site bbc.com/news/science-environment-47151778 you can take a closer look at the design. The question would be ( not your question :)) if the unfolding motors can work independent from each other and get commands from Earth ? $\endgroup$
    – Cornelis
    Aug 28, 2019 at 10:03
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    $\begingroup$ answer seems related: space.stackexchange.com/a/63914/40489 $\endgroup$
    – blobbymcblobby
    Jun 30 at 7:56

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Theoretically, yes the Rosalind Franklin rover can tilt its solar panels to get martian dust off of it. But I think that once the solar panels are deployed, it's not able to tilt it individually, instead it has to tilt the whole rover, similar to the Mars Exploration Rover Spirit. How Spirit came to not operational is related to the OP's dust question so I figured that it's worth mentioning.

In 2010, Spirit's solar panels were getting covered with dust, and unlike Opportunity, it didn't have the same amount of luck with dust devils that periodically cleaned Opportunity's solar panels. Spirit is located in the southern hemisphere and winter was approaching and NASA wanted to tilt the rover for maximum sunlight exposure, however they couldn't as the wheels were stuck. Spirit had a tilt of 5° toward the south, however the Sun crossed low in the northern sky; so Spirit lost power (source). Basically, this means that the Rosalind Franklin rover will most likely not be able to control its solar panels individually as many other rovers can't, and moving parts are prone to failure thus the solar panels can be stuck tilted the wrong way which can jeopardize the mission. Also if you look at how the solar panels deploy, any dust that slides off can land on other solar panels, so the most favourable option would be to tilt the entire rover which I will explain.

The Rosalind Franklin rover can handle maximum slopes up to 35° based on recent testing (source). According to this summary report of Spirit, Spirt almost reached the angle of repose during its mission.

Spirit [was] also at some of the highest tilts of the mission and very nearly at the angle of repose. When the slope exceeds the angle of repose, dust, sand and other granular material slide downward. Spirit has been trying to take advantage of the steep tilt by spinning the middle wheels before driving to shake dust off the arrays.

The highest tilt in the mission which was 29.9°, meaning the angle of repose of martian dust is around 30-31°, within the range of the Rosalind Franklin rover.

Summary: Its unlikely that the Rosalind Franklin rover will be able to control its solar panels individually after they are deployed for multiple reasons. Moving parts are more likely to fail. If a motor fails during the process of cleaning, the panels will be stuck at an angle meaning sun light won't reach it, providing even less power. The ways the rovers solar panels deploy means that any dust they does slide off will slide onto other solar panels, which is not good. Furthermore, deploying solar panels take a long time. This is true for all landers and rovers. To give you a sense, here's InSight deploying its solar panels (there's no video of ExoMars deploying its solar panels).

The best option would be to tilt the whole rover to the angle of repose of martian dust, or just be lucky and hope dust devils cleans its solar panels.

Sources:

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    $\begingroup$ So currently we don't know if the panels can tilt after being deployed or not; you don't think so "for multiple reasons" which are (paraphrasing) 1) motors can fail, 2) dust from one would simply fall back on another (there are big gaps between one panel and the next shown in my images, so this isn't obvious to me, I think ) and 3) it would take a long time (why is this a reason? after a 3 day storm, so what if it took even a few hours?) $\endgroup$
    – uhoh
    Aug 29, 2019 at 17:39
  • $\begingroup$ @uhoh Yep we don't know. But it's likely because many other rovers lock their solar panels after they're deployed. Btw, I saw the big gaps but then wind came to my mind, if dust falls on the stationary solar panels (the ones behind the mast), you can't tilt those ones. "3) It would take a long time". That kind of correlates with number 1, more time = more likely for motor to fail. Probably why rovers deploy their panels only once. Again dust on the stationary solar panels can only be removed if the whole rover is tilted (near 30 degrees). $\endgroup$
    – Star Man
    Aug 29, 2019 at 17:44
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    $\begingroup$ Okay, so "we don't know" is your answer? I think most of this doesn't address tilting. It might be better as an answer to this general question which asks "How will the ExoMARS Rover keep its solar panels dust-free and collecting sufficient power?" and "...what management techniques are begin considered for the ExoMARS rover to handle covering of the horizontal panels by dust, or low solar elevation in 'winter'? $\endgroup$
    – uhoh
    Aug 29, 2019 at 17:53
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    $\begingroup$ @uhoh I guess the official answer is "we don't know" but i think it's most likely "no". $\endgroup$
    – Star Man
    Aug 29, 2019 at 17:56
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Um, in 2009, it did have tilting solar array ability. But not for dust removal.

OP's question: Will the Rosalind Franklin (ExoMars) rover solar panels be able to clear themselves of dust by tilting?

Short answer is threefold:

  • Currently: no

  • In the past, tilt was planned. See below.

  • In the future, they are looking at various options. See below.

Back in 2009, maybe, as tilting was mentioned, but dust removal was not the original reason for them tilting.

The tilting was meant for dusk/dawn solar optimization.

With the 2022 rethink with ExoMars not going before 2028, they could go back to looking at adding in tilting for dust removal.

enter image description here

https://www.lpi.usra.edu/mepag/meetings/archive/meeting/2009-07/04-Mepag_Coradini.pdf

Mike Williams, Chief Engineer at Airbus Defence and Space, said that when the ExoMars mission was first conceived, engineers considered a plethora of dust cleaning technologies, including brushes, wipers, gas blowers and electrostatic wipers to get rid of the dust. At that time, they decided the rover, whose nominal mission in Oxia Planum was designed to last only 180 Martian days, or sols, did not need to self-clean. With the new launch date now expected no earlier than 2028, they are rethinking their approach again.

"With ExoMars now being reborn, we are looking at possibly reinstating some of that capability," Williams said. "We could use something like solar panel tilting to possibly dislodge some of that dust. It would also help point the panels more efficiently at the sun, which may also have some benefits."

Shake mode

in addition, engineers are thinking of making some upgrades. One of these could be a shake mode that would enable Rosalind Franklin to periodically rid itself of the Martian dust that over time would gather on its solar panels and reduce their efficiency.

https://www.bbc.co.uk/news/science-environment-63336201

https://www.space.com/saving-mars-robots-from-death-by-dust

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As it stands, the current version of the rover has no ability to tilt its arrays.

The Rover vehicle solar array assembly (SAA) is made of a fixed panel and four deployable (primary and secondary) panels. This SAA is unique with respect to standard deployable systems because of the motor deployment control and trimming possibilities during Martian soil exploration.

For the rover SAA the biggest challenge is related to surviving Mars planet environment (i.e. dust, wind and charge accumulation) and the associated mechanical and electrical constraints.

For ..the arrays European PVA technology was exclusively used: more specifically high efficiency III-V compounds solar cells and a new glass grounding network.

SAA characteristics:

  • The six hold downs (three on each SAA side) hold the two panel stacks in position during the travel to Mars, and after landing they release the panels by non-explosive actuation.
  • After hold down release, the active hinges deploy sequentially the panels till latching in the deployed position. Once in the deployed position, the deployment mechanisms withstand passively the panel loads.
  • The equipment is designed to withstand the specific environmental conditions of the Mars mission, including, among others: minimum temperature of -130 ºC (during nights on the Mars surface), maximum temperature of +125 ºC (for sterilization before the mission), dust environment (due to storms in the Mars atmosphere), panel deployment against Mars gravity and wind pressure, and fatigue in deployed configuration (due to Rover mobility loads on the Mars surface).
  • The tests performed at mechanism level include sterilization, functional, vibration, shock, dust, thermal and life.
  • The tests performed at SAA level include functional, deployed static load, vibration, acoustic, thermal vacuum, sterilization and deployed configuration fatigue.

So current SAA characteristics no longer include tilt capability as listed back in 2009.

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EXPLORING MARS WITH SOLAR-POWERED ROVERS

.., there has been some interest in developing means to mitigate the effect of dust on the solar arrays for long-duration operation on Mars.. however, the engineering decision was that it would be more cost effective to oversize the arrays to account for the predicted degradation than it would be to fly a system to remove dust from the panels.

Since the operating temperature varies significantly during the day, and the spectrum of the incident sunlight varies both with time of day and with the amount of dust in the atmosphere, the performance of the solar arrays on Mars is complicated.

https://www.e3s-conferences.org/articles/e3sconf/abs/2017/04/e3sconf_espc2017_04002/e3sconf_espc2017_04002.html

https://prod-sener-aeroespacial.geanetondemand.com/en/products/solar-array-assembly-mechanisms-for--exomars-2022-rover

https://ieeexplore.ieee.org/document/8932077/metrics#metrics

https://ntrs.nasa.gov/api/citations/20060013412/downloads/20060013412.pdf

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