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djdsf t1_iu2nasb wrote

I'm stupid compared to these fine folks that make this tech, but has nobody ever told them to stick like a brush or something that can run electrically and clean the solar panels?

If I have 10% power remaining, i might as well use 8% of it to clean the thing that generates power instead of praying the wind cleans the panels.

Or is there a reason why we can't attach an electric brush but we can attach drills and all this other stuff?

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gribblefrit t1_iu2vll0 wrote

In the documentaries they talk about complexity. Every little gizmo, servo, control board and gadget they include is doing double or triple duty. They all have redundant systems. It all adds up to a very complex machine. They do things like tilt the panels to shake dust off, but adding the complexity to clean the panels is super hard and, in the long run, not effective. In specific cleaning solar panels with a brush could degrade the panels faster than leaving them alone, theee aren’t the reinforced shatterproof panels on your roof. They are so light weight and delicate that even a brush could damage them. This is some of the balancing act they take each time they send a rover up. How long to get a return on investment so to speak and how long before it goes to sleep.

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grim-one t1_iu3hvuu wrote

OK, OK... We'll spring for a soft brush for the delicate panels :P

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Nidungr t1_iu3o10k wrote

The problem isn't the hardness of the brush, but the dust. It is harder than any sufficiently lightweight material we could make solar panels out of.

Apparently brushing off the dust would just replace opaque dust with opaque scratches, if the panel isn't already sandblasted to hell to begin with.

Edit: The dust is electrostatically charged and clings to surfaces, so you can't easily tip/blow it off.

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WimpyRanger t1_iu3xhlo wrote

If it’s electrostatically charged, then you could induce a new charge to eject the dust, yah?

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tea-man t1_iu40jsk wrote

If I'm not mistaken, this is exactly what's beginning to happen with some of the more advanced solar power projects. Though it is very new technology requiring precise control of the electric fields in individual layers of the cells, so it's still a few years away from large scale adoption.
I suspect that any solar powered rovers that began their initial design in the past year or so may adopt this if it's proven successful.

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plzsendnewtz t1_iu41ndf wrote

Rotate the shield harmonics! Aye, Captain!

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enderjaca t1_iu46cj2 wrote

Reverse the polarity in the deflector array by negative 5! I cannae captain, it won't respond!

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alex_sz t1_iu3o6j6 wrote

A directed blow of air would do nicely I imagine

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Dsiee t1_iu3tk99 wrote

Not much air on mars, sorta why the wind isn't the best at cleaning. Also the dust is actually somewhat stuck as it has a static charge.

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dangly_bits t1_iu3smgi wrote

I would imagine the required air pump would not only use far more energy than the rover has on tap and would likely be one of the first fail points.

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colt_420 t1_iu4wbdk wrote

What if it just runs constantly like an air hockey table (Half joking half not mostly just wanted to be another random Reddit or with useless ideas here) Hi everyone :)

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Tricky_Invite8680 t1_iu3wvyr wrote

estimated 2 years, actual 4 years service life. I'm thinking maybe they can redesign the panels to have some kind of thin film cartridge that can basically renew the surface at least once. maybe even an antistatic film to boot. the land based ones must have more structure on the panels then an orbiter.

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wartornhero t1_iu407ys wrote

And weight budget. At the end of the day they can only send what they can launch and land in one go currently. So if you spend 1 kilogram on a system to clean panels that is 1 kilogram where you don't have a science instrument. It is also like 100 kilos in propellant to get that 1 kg to the surface.

So yeah it is usually better to just try other means of keeping them clear that may extend the life but may not.

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bathroomheater t1_iu43b00 wrote

So if you have the ability to tilt and move why not give it the ability to swing upside down and tap gently against the rover to knock the dust off

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enderjaca t1_iu46rys wrote

Because it's very light dust that is electrostatically attached to the panels. Tapping wouldn't do much. And as other folks have mentioned, adding more complexity to the rover means a greater chance of failure and adding more weight, which means more cost, and that you have to choose what other scientific instruments you can't include because you have a maximum weight/cost limit.

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bathroomheater t1_iu4gwki wrote

So I guess sci-fi shows have lied to me all my life and reversing polarity after randomly slapping a keyboard also won’t solve it either

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enderjaca t1_iu4l323 wrote

Anytime I get mad and slap a keyboard, I solve that problem and boom, I instantly have a different problem. Molotov cocktails work the same way.

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DeifiedExile t1_iu47ik9 wrote

You can't just knock the dust off. It's electrostatically charged, so it clings to the panels like a magnet. Additionally, those panels are significantly more delicate than what your average earth-based panel.

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Alt-One-More t1_iu4wx00 wrote

I hear this a lot but I just never understand the reasoning given. There's no way it isnt possible to clean off the panels, it's more likely funding issues in the design as well as the official "lifespan" of these probes being months not decades.

Ie they'd rather save the weight on a cleaning mechanism in order to add another scientific instrument.

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Hennue t1_iu3x6hk wrote

If the panels were as delicate as you say here, they wouldn't survive launch and EDL.

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BecomingCass t1_iu40ppr wrote

I'm pretty sure they're folded up until after landing. Nothing to get scratched on

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Rainbowdelights t1_iu3cjm5 wrote

A counter argument to this is the billions of dollars spent to land this thing and do all the rest, could completely mitigate this cause of failure through the addition of a few relatively inexpensive parts

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BirdOfSteel t1_iu3dr9a wrote

Spacecraft engineers would love nothing more than to implement all the features they will/might need if they could afford it. When your budget is determined by the government, ya take what you can get

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Throwaway_97534 t1_iu47auh wrote

But when almost every successful lander is limited by their solar panels at the end of the project, at what point do you start prioritizing them?

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BirdOfSteel t1_iu49qny wrote

I'd say you'd need to start spending more time/money on solar panels if the of one really needs it to function. So far, probes seem to be getting by fine with the current panels we put on them so there isn't too much pressure to be focusing on solar panels if they're doing the job well enough.

I think someone else also mentioned this, but adding things like wipers and whatnot would also increase weight. That's weight which could be dedicated to other important parts of the craft. Yes, you'd end up collecting more power and perhaps you'd maintain your solar cells better than before if you cleaned them, but it would take research and development on something that already works well enough.

That said, solar is something that's useful down here on the ground too, so I imagine that takes some pressure off of space agencies develop the tech from the ground up.

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Star_king12 t1_iu3ftjl wrote

Anything you send to Mars is excruciatingly expensive.

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Sabrewolf t1_iu3508t wrote

I work internally with some of the Mars teams at JPL, and these are the best explanations I have:

  1. Budget budget budget, many of these missions have a cost cap which can't be surpassed. Every additional thing adds system complexity, and ultimate ends up costing money to design/build/test. Even if there's an amazing idea floating around, if it's not in the project budget it's a no go. This includes solar panel dust removal, weighed against the expected science return and lifespan of the mission.
  2. Martian dust is electrostatically charged, so it "sticks" to the panels rather than sits on them. This complicates removal.
  3. Brushes are abrasive, and so is sand and dust. On top of the weight and mechanical complexity, point #2 means that you'd have to basically scrape dust *into* the super delicate solar panel to remove a marginal amount of debris. All said and done, wipers/brushes are not effective for this reason.
  4. Blowers and fans, see point #2, especially relative to the amount of force such a device could apply as compared to a wind clearing event like atmospheric wind. Additionally, Martian dust is so fine that attempting to blow it away with fans/blowers sort of causes a floating cloud that gets sucked back into the fans, essentially turning it into a sand blaster.
  5. There are methods of generating a burst of electric charge to displace the dust, but these are very expensive, very complex, and have not be fully investigated yet.
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cjgranfl t1_iu5jg2t wrote

Great info; interesting. Thanks for sharing.

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WimpyRanger t1_iu3xqde wrote

  1. There’s absolutely no way that generating a charge to displace the dust would be very complex, or very expensive relatively speaking.
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minepose98 t1_iu49j7d wrote

I wonder who is more knowledgeable about this, someone who works with this stuff, or a random redditor? Who looks at a post from someone who knows more about the subject than you explaining the difficulties of something and says "bet it can't be that hard"?

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WimpyRanger t1_iu7fl3b wrote

Well, I did go to school for electrical engineering, and a number of my friends work in space systems at Ratheon.

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PayZestyclose9088 t1_iu54b2r wrote

Omg youre so smart. You should apply to help make the rovers. I bet you will be making the next best thing

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Sabrewolf t1_iu81nw5 wrote

So the most promising technology NASA has funded for electrostatic displacement of dust in a way amenable to a space environment is called EDS, or an Electrodynamic Screen.

This is essentially a layer that fits over the solar panel with some electrodes embedded in it, patterned in a way that allows us to "walk" dust off the panel using a specific sequence of charge bursts. At first glance this seems like a silver bullet, however this technology has yet to leave the prototyping lab and make it onto a Mars mission for several reasons:

  1. Efficiency. The presence of these electrode layers has been found to cut the power output of the panels by 15-25%. This is a no-go, until further developed.
  2. Cost. Since this is very new, no industry has developed to marginalize the cost of making these. Since they are essentially still lab prototypes they are still very expensive to make, which makes allotting funding for them kind of tricky. Class B missions (like InSight) have less $$$ available, and Class A flagship missions (like the rovers) are important enough to have an RTG provide power. So at present, this technology is sort of stuck in the middle between function and price; at a certain point you have to ask, if the mission is so important that it *needs* to work long-term, why not just use an RTG? Especially when almost every previous solar panel based mission lasted decades without such a technology.
  3. Safety/Reliability. A key point of an EDS is that it produces charge using voltages in the kV level. This runs the risk of arcing/damage at a certain point (Paschen's breakdown for the engineers). The breakdown voltage at which an arc forms depends a lot on the atmosphere, and we simply need further research into the composition of Mars dust in order to safely design an EDS that guarantees minimal risk of arcing.

TL;DR - It'll get there, it's not there yet.

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WimpyRanger t1_iu87x57 wrote

What is the top layer on the rover panels? If the dust clings, the layer must hold a static charge. Given that the panels can rotate to shed the dust, and if they could also be charged to repel the dust, that seems like a clear win. If such a coating is not efficient enough, could you not use a grid type pattern? The EMF would still apply all over to some degree without absorbing much.

(Thank you for the reply)

Also, why couldn’t the panels be held near vertical to avoid the issue altogether?

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Sabrewolf t1_iu8932v wrote

You are greatly overestimating the amount of mechanical force an EM field can apply to electrostatically charged martian dust. Even at the kV level, an EDS panel cannot "pop" dust off. Nor does charging the panel allow dust to become mobile enough to passively slide off without further EM interaction, even if the panel were angled.

The way an EDS works is by shifting the dust by alternatingly charging the patterned electrodes in the screen. Because EM field intensity falls off with the square of distance, this pattern is required to keep the dust close to the charged electrodes.

And all this still ignores the issue of Paschens breakdown.

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alle0441 t1_iu2pje5 wrote

It's more just that the probe isn't designed to last a long time. Original designed lifespan was 2 years and it's coming up on 4. Sure they could do things to extend the life, but that would be spending extra time, money, added weight, complexity when the requirements don't ask for it.

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moeriscus t1_iu2qrbm wrote

Fair point, but I think it's obvious that NASA lowballs the expected lifespans in order to avoid overpromising/underdelivering to the public and to budgetary committees

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Lasombria t1_iu2xp16 wrote

My father worked for JPL for 40+ years, and no, they really don't. What they do is make the projected lifespan as guaranteed as possible. A happy side effect of that is these great extended-mission lifespan, but the goal is hitting the primary lifespan securely.

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moeriscus t1_iu2yxy9 wrote

Ah, thank you for your insight!

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Lasombria t1_iu385pf wrote

Glad to help. :) Dad loved to about distinctions like that.

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Dsiee t1_iu3txgw wrote

No, it is an artificat of designing for a high sucess probability. For a simple example, let's say you want a robot for a 1 year mission with 90% probability of it lasting two years. You design the robot so that it has a failure rate of 5% per year. As a result it is highly likely (~80%) that it will last four years or twice the required mission length.

Obviously this is a very simplified example, but hopefully it illustrates the point that you cannot easily determine the exactly lifespan of a piece of equipment.

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djdsf t1_iu2q0ea wrote

While that's true, wouldn't the argument that keeping something alive for longer is also cheaper than building a whole new one and sending it to space again?

I'm understand new tech as well, but come on, there has to be a world somewhere where keeping this thing alive for an extra year for maybe $3M more is cheaper than sending another one that will run 3 years for $70M right?

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Count_JohnnyJ t1_iu2qzi0 wrote

"Cheaper" doesn't matter when you have X budget, and if you don't spend it, you'll have a smaller budget the next year because you obviously didn't need that much.

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Ex_Machina77 t1_iu3txs8 wrote

That only applies to rolling budgets like the US Army utilizes. But essentially that's a myth propagated by terrible supply personnel, who failed to do their jobs properly.

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CartmansEvilTwin t1_iu39520 wrote

That's not really how this works.

These things have a specified lifetime of e.g. 2 years. That means, each component is built and designed to last 2 years with a probability of 99,9%. That in turn means, that there's a high likelihood for the device to survive much longer then two years. Adding additional safety margins for a designed lifetime of 4 years will make the whole thing much more expensive and maybe even less capable, simply because it's going to be heavier.

And additionally, NASA engineers often enough hack devices to work much longer. The Kepler telescope for example had one too many reaction wheels fail and was thought to be dead, but some clever engineer find a way to use the remaining ones to still do some science.

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cjgranfl t1_iu2owsq wrote

Great question; I kind of wondered about that one myself. It seems technically feasible.

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CaveDeco t1_iu2xhvk wrote

It’s mostly weight that is the issue. Ounces/Grams matter so you have to choose very carefully what to include. Adding a brush means something else may need to be removed. So you have to make strategic decisions on what’s most important. A longer lifespan but less data, or more data but a shorter lifespan.

Even without it, Insight has still been operational twice as long as it was expected to last.

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PiBoy314 t1_iu2zs11 wrote

While there are other methods of getting dust off, Martian dust is fine and sharp enough, having not been eroded by water, that it would scratch the solar panels as it was scraped off.

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Delicious-Ad-9519 t1_iu39o1q wrote

They should take it to the car wash

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deva5610 t1_iu3kr4z wrote

>They should take it to the car wash

Yes!

Next mission to mars drops off a drive through car wash for all the rovers to use. Genius.

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claireauriga t1_iu3ibid wrote

One of the challenges is that in a very low pressure, dry atmosphere like on Mars, electrostatic effects on dust are very powerful. This means that a dusty surface is harder to clean. You know if your TV has dust on the screen, and you wipe it, but you can never seem to get all the dust off? It's like that but turned up to eleven.

Obviously when dust buildup gets bad enough, cleaning would still be beneficial, but it's always going to be harder than a quick brush or wipe.

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icbint t1_iu3ka44 wrote

Without water cleaning it in a meaningful amount is too hard

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SirThatsCuba t1_iu6vrpw wrote

Just put one of those films on it like you get on new electronics, and have the rover peel it off. Bam, new solar panel, no dust.

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Zealousideal-Ad634 t1_iu2ua3m wrote

Or just the ability to vibrate the Solar panels.

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Ex_Machina77 t1_iu3tlxx wrote

The dust is stuck to the panels through electronic static and won't just "shake" off... The winds on Mars are more then strong enough to blow the dust off if it wasn't stuck there through the static charge

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ammonium_bot t1_iu6z0ja wrote

Did you mean to say "more than"?
Explanation: No explanation available.
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Emmaleah17 t1_iu4mg8y wrote

This is a great idea. Literally like windshield wipers for the solar panels. Boom problem solved. Shouldn't be hard to install and should operate on very little energy.

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nom_of_your_business t1_iu39gsh wrote

Some of the very smartest people are kinda stupid when it comes to stuff like this. Not a slight just an observation. Super focused on bleeding edge solutions but not thinking about minor issues

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LabSquatter t1_iu3fyv5 wrote

It has nothing to do with being super focused and forgetting something. It’s just that often engineering problems can look simple from the outside looking it, but are significantly more complicated in reality. “The rover getting dust on it” wasn’t something they just forgot.

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