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Interesting thread on why it's not possible for the solar panels to be self cleaned: https://twitter.com/NASAInSight/status/1590736220199735296?cxt=HHwWgMDShcGK

Interesting thread on why it's not possible for the solar panels to be self cleaned: https://twitter.com/NASAInSight/status/1590736220199735296?cxt=HHwWgMDShcGKt5MsAAAA https://twitter.com/NASAInSight/status/1590736220199735296?c...

prettyStandard 4y ago
They would rather contribute that cost&weight&complexity to just more solar cells. Got it.
logicallee 4y ago
After reading your note "why it's not possible for the solar panels to be self cleaned" I clicked through and as I clicked I was thinking "okay so obviously it is possible for the solar panels to self-clean. prove me wrong." I mean how hard could it be? No way is that an "impossible" task. I went out of it thinking, "yep, look at these excuses we are making for the state of robotics." - the quote is: "A system like that would have added cost, mass, and complexity. The simplest, most cost-effective way to meet my goals was to bring solar panels big enough to power my whole mission – which they did (and then some!)." So robotics is at the state where it is possible to send a rover to Mars, but a simple robotic arm can't easily brush off some dirt. The lander weighs 789 lb and the cost-effective solution is not try include a simple cheap lightweight robot arm that is foolproof and can easily sweep some dirt, because there is not such thing. Robotics isn't at the level where that is easy, cheap, or lightweight. If a human could reach through a portal to there with a brush, it would take less than five minutes to brush off the dirt that had fallen on solar cells. A simple, light, and foolproof robotic arm that can easily do that doesn't exist. Now that we have superhuman levels of general AI in chatgpt, isn't it time to work on foolproof and lightweight robot arms for all sorts of tasks?
- gpderetta 4y ago
  "A high resolution picture of the Insight Mars Rover on mars, with a simple, light weight and foolproof robotic arm brushing sand off its solar panels, in the style of Greg Rutkowski and Alphonse Mucha, 4k, trending on artstation"
- blululu 4y ago
  I would suspect that the problem is more difficult than you make it out to be. First, Mars is very windy/dusty. Second, there is no water so brushing dust is harder than on earth. Add in the increased static cling and dust ingress into the motors and it is not clear to me that brushing is actually viable on mars without a lot of extra engineering (and teams to figure all this out). I’m sure this decision was made with a good e evaluation since they did make the choice to add more panels which has its own downsides. There might even be some interesting papers out ther.
  - m4rtink 4y ago
    What about compressing some of the atmosphere and then releasing it repeatedly from close proximity over the dusty panels? Given the very low atmosphereric pressure on Mars, a bit of gas at terrestrial sea level pressure equivalent would do wonders. As for downsides - you need a compressor and some filtering to avoid clogging your gas system with dust (thats likely the main obstacle). Still doable IMHO and I'm sure followup probes and eventually settlements will find how to handle Martian dust efficiently.
- adamsmith143 4y ago
  You did it, you solved RObotics! Someone get this guy a Nobel Prize!! JPL Engineers are no match for his staggering intellect!
- Retric 4y ago
  Most critically, other components are also failing so you don’t get that much more lifespan with unlimited power. A brush doesn’t work well in a zero moisture environment. The dust is horrifically abrasive and brushing it along the panels would cause damage. The added weight would have to be compensated for.
  - m4rtink 4y ago
    Well, the MERs lasted quite a bit longer & were moving systems. A bit of a shame a static lander can't beat them. :P
    - Retric 4y ago
      Insight isn’t dead just hibernating which both MERs did several times. If Insight dies then Spirit will have lasted 50% longer and opportunity significantly longer, but both rovers lost quite a bit of functionality over time. So, the difference isn’t as stark as you might assume when you consider how much time rovers spent with reduced power or hibernating, stuck, etc.
- nradov 4y ago
  ChatGPT isn't general AI, not even close.
  - logicallee 4y ago
    [1] Although ChatGPT might not meet some special elevated standards for what is considered general AI, it is able to solve a wide variety of generalized requests, including writing this response on command. In this sense, it is similar to SpaceX being a "real" rocket company, even though it is a private company with less experience than NASA. SpaceX has disrupted the traditional aerospace industry and demonstrated that it is capable of designing and launching successful space probes, despite not being a traditional "establishment" player. Another analogy might be to Uber, which has revolutionized the transportation industry by offering a new way of connecting riders with drivers through a smartphone app. Uber may not meet some traditional definitions of a "taxi company," but it has proven to be a successful and popular service for millions of people. A third analogy might be to the smartphone itself, which has become an essential tool for many people despite not being a traditional computer. Smartphones have disrupted the personal computing industry and offer a wide range of capabilities, from making phone calls and sending texts to accessing the internet and running apps. Similarly, ChatGPT is able to complete many general requests that meet the expectations of many users, even though it might not meet some definitions of general AI. It is able to do this because it is able to perform a wide range of tasks, including writing this comparison at your [my] request. Of course, ChatGPT has its limitations and is not a substitute for human intelligence. However, it is able to complete many tasks that would be challenging or impossible for chatbots of decades ago, which demonstrates its usefulness and capabilities as a tool for assisting users with a wide range of tasks. I hope this helps clarify my personal feelings about ChatGPT's intelligence and capabilities. It is important to recognize that different people have different standards and definitions for what constitutes general AI, and that is completely fine. What matters is whether a tool is able to meet the needs and expectations of its users, and ChatGPT has certainly been able to do that for me and many other users. -- [1] I want to clarify that this response was written by ChatGPT, a large language model trained by OpenAI, at my request. For more context on my request and the interaction with ChatGPT, you can view the full exchange at https://hastebin.com/raw/wolovegiqa https://hastebin.com/raw/wolovegiqa
- ericbarrett 4y ago
  I agree with you, and I think the other replies are missing your point. With all the techno-marvels around us, it's a shame that lightweight, reliable robotics that can do something as superficially simple as brush some panels don't exist. Just goes to show how hard the field is, I guess.
  - logicallee 4y ago
    Yeah, they really don't get what I meant which is probably my failure to communicate. It's like me saying "It's a shame I can't save myself a few minutes every day by having a robot make my sandwiches for me, since there is no such thing as a cheap household robot that can easily make a sandwich from its ingredients put before it" and them saying, "nono there totally are they just cost too much so it doesn't make sense and you don't understand anything about the intrinsic difficulty of sandwich assembly in a zero-person environment". Okay fine but end result is I'm still making my own sandwich in 2022 :) End result is this mars rover can't do $2 worth of human work because it can't brush itself off, it is easier to add larger solar panels than brush them off since there's no such thing as a cheap lightweight easy reliable robot arm.
- hn_throwaway_99 4y ago
  This reply completely misses the point. All missions have an expected lifespan. The reason why they didn't use some sort of cleaning system is simply because it wasn't needed. The lander gathered all the data it was expected to, and then some. Why add complexity if it isn't useful?
  - mturmon 4y ago
    ^-- This is the answer: this capability wasn't needed to fulfill science objectives. End of story. To add context: InSight was proposed to a cost-capped, competitive NASA program. Within competed programs, you can't spend money on nice-to-have's. You have to come in under a cost cap, while demonstrating you will achieve science objectives. Period. The science objectives are carefully time-bound by a very knowledgeable science team, and from those science requirements, all the engineering requirements, including lifetimes, are derived. InSight didn't need more than one Mars year for the science, so that's that. There were 2 instruments. In the case of the heat probe, they needed to observe at least one full annual heating cycle. For the seismograph, I think they had an approximate event rate and they needed to capture X number of events of a given magnitude to get insight (heh!) into the subsurface structure. Here's a description of how this works in general, from someone who was involved in InSight formulation and who is in the leadership of mission formulation at JPL: https://science.nasa.gov/science-red/s3fs-public/atoms/files/Launchpad_Session3_STM_18Nov2019_smf_final.pdf https://science.nasa.gov/science-red/s3fs-public/atoms/files... The whole presentation is great: the first introductory slides, some InSight examples, and the last 3 slides in particular give background on some of my claims above. The person who (with the PI, Bruce Banerdt) led the InSight "requirements trace" is Peg Frerking (https://scholar.google.com/citations?user=t6XZBAIAAAAJ&hl=en https://scholar.google.com/citations?user=t6XZBAIAAAAJ&hl=en), who is now a JPL fellow in part because of her work in adding engineering rigor to the formulation process. As this thread shows, it's very easy for clever engineers to add on nice-to-have's that are not required to meet science objectives. That's how you get overruns. Here's another recent HN reference point on capabilities that don't contribute to a great product: https://news.ycombinator.com/item?id=34032672 https://news.ycombinator.com/item?id=34032672 [Steve Jobs Insult Response]
  - rob74 4y ago
- funderbus 4y ago
  This is more about "What are you willing to bet the mission on". The mission being a billions of dollars and years of effort. And mission success is defined as working for a limited time. In aerospace "simple" beats "slightly more complex but much better" often.
input_sh 4y ago
I don't see that thread claiming that it's not possible, just that it wasn't the most practical choice for this particular rover.
- delecti 4y ago
  It's possible for the solar panels on rovers to be self-cleaning, but it's not possible for the solar panels specifically on Insight to be self-cleaned.
- grawp 4y ago
  Insight is NOT a rover. It's stationary unmovable lander.
wazoox 4y ago
It's pretty amazing to think it still works with the panels as covered in dust as they are in the last frame!
- jws 4y ago
  Solar panel output is remarkably resilient to visible dirt. I have an installation on a seagull rookery. As you can imagine things get thoroughly “whitewashed”, especially since the top edge of the angled array is prime “standing around squawking and crapping” space. They can be covered to the point that there isn’t a clean spot the size of your fist anywhere on them and they will still be putting out 75% of their rated power. I suspect it has something to do with the non-linear response of the human eye. You don’t have to reflect a lot of light to be perceived as significantly lighter than black, so diverting 25% of the light from the panel to reflected light makes the panel look quite light.
ilyt 4y ago
So its essentially "the system needs to be cheap and light enough to beat bringing more panels"
- dougmany 4y ago
  I remember calculating the cost efficiency of adding a sun tracking mount to some panels. It turned out that the increased power would be about the same as adding an additional panel and one panel was cheaper than the mount. The mount also would only help half the year and the extra panel would help the whole year.
  - implements 4y ago
    If your array is at ground level it still might be worth being able to manually adjust the mounting angle for different seasons (high sun / low sun).
  - andrewflnr 4y ago
    But would the sun-tracking mount also let you shed dust buildup? That might make it worth it for long term missions. My next idea after blowers for removing dust was to just flip the panel vertical for a bit...
  - ilyt 4y ago
    Well, till you run out of roof space.
MobileVet 4y ago
If only there was a simple mechanism, maybe a four bar linkage, with trillions of cycles of testing... it would have to be light weight and include some form of brush or wiper and function with significant forces applied, similar to wind from a moving vehicle... I guess the downside of having JPL in SoCal is that none of the engineers are familiar with windshield wipers. <jk>
- adamsmith143 4y ago
  "A system like that would have added cost, mass, and complexity. The simplest, most cost-effective way to meet my goals was to bring solar panels big enough to power my whole mission – which they did (and then some!)."
  - MobileVet 4y ago
    It was a joke... simplicity is always best.
Communitivity 4y ago
I am seeing a lot of comments along the lines of 'windshield wipers?' Cars were invented in 1886, the first windshield wipers became available for them in 1917, 31 years later. That is... - in an environment with plenty of water - not near waterless, - on glass windshields (much less fragile than solar panels), - where we can physically replace the wipers when needed, - where we can adjust if they get stuck, - and where there is much less dust. If we add 5 years of R&D to overcome each of those obstacles (very optimistic, it's more like 10 well-funded years I suspect), then even optimistically we're looking at 25 years. I suspect we might have a rover with self-cleaning panels, or safe cold-fusion, in 25 years. I don't expect one this decade.
- Mistletoe 4y ago
  That’s the most bizarre math I’ve ever seen. Once you’ve designed something once it’s a lot faster to design over and over.
  - Communitivity 4y ago
    Each one of those bullets is a different engineering problem. The math is based on real government R&D I've seen. "Once you’ve designed something once it’s a lot faster to design over and over". You forgot the last part of that sentence: Once you’ve designed something once it’s a lot faster to design over and over, if you are in a similar environment with somewhat similar conditions.
    - chasd00 4y ago
      > government R&D I've seen oh, now i understand the math
- deleted 4y ago
  [deleted]
- hn_throwaway_99 4y ago
  The tweet thread itself doesn't say that using self cleaning panels would be impossible, or even that hard, just that it's easier and more cost effective to just bring bigger panels. Not of your bullet points seem that relevant honestly - using an equivalent of a leaf blower would do the trick. But any added complexity to a mission just means there are more failure points.
photochemsyn 4y ago
Given the success of the helicopter drone (Ingenuity) on Mars, I wonder if that's an option for cleaning solar panels - i.e. put a simple rotating brush/fan system on the drone, keep it in a port on the main lander, and every once in a while, launch it and have it land on the solar panels, where it does a roomba routine. Since drones already expand the abilities of a lander, i.e. exploring the immediate area and collecting samples, this wouldn't be much of an added cost.
- pbhjpbhj 4y ago
  Or 'just' have a mini roomba on each panel?
- kitd 4y ago
  Or have the drone fly low over the panels, making use of the down-draught.
Mistletoe 4y ago
Who decided to anthropomorphize the rover like that? It’s creepy and honestly scientifically dishonest, like the rover has intelligence and is writing the posts. Something for children, but children hate being fooled like that and being talked down to. It’s something I might expect from the current version of NASA though.
- brrwind 4y ago
  It's... the twitter profile of the rover, it's not that big of a deal
- Toutouxc 4y ago
  I don't find it any more disturbing than buying car tires from the Michelin tire guy (he's actually called Bibendum) or getting batteries with the Duracell Bunny on them. Some people, even educated and technically inclined people, like their tech a little anthropomorphised.
JoeAltmaier 4y ago
Cant just use a pad on the arm to rub away at them?
- Zancarius 4y ago
  What happens when the pad gets choked out with dust?
  - dredmorbius 4y ago
    Great Mars-dust-wiper pads have little Mars-dust-wiper pads upon their backs to wipe 'em. And little Mars-dust-wiper pads have lesser ... pads, and so ad infinitum. It's pad's all the way down.
  - JoeAltmaier 4y ago
    Squeegee then. You get the idea.
- c22 4y ago
  Since we're throwing stuff at the wall how about flexible solar panels wrapped like a tank tread that roll past a stationary wiper arm?
- andrewflnr 4y ago
  I'd go with a brush, actually.
zackmorris 4y ago
I don't buy it. There are so many ways to solve the problem that wouldn't add significant weight, that there must be some ulterior motive. And there is. NASA plans obsolescence into the rovers to get funding to build the next rover.
- nradov 4y ago
  This type of arrogant, aggressive ignorance is really the worst part of HN. How many successful space probes have you designed? How much weight would the solution add, and what trade-offs would that impose on other mission parameters? NASA is by no means perfect. But we can start by assuming they have basic competence and positive intent unless proven otherwise.
  - zackmorris 4y ago
    I'm not doubting their competence, they're the best of the best IMHO. But sometimes politics and economics overshadows the work.
    - zackmorris 4y ago
      Hey nradov after sleeping on it, I agree with you, I don't like the tone of my original comment. Probably every engineering team at NASA who was part of Insight had a say in whether to invest an ounce in a dust cleaner or another sensor, and they went with the sensor. Who are we armchair warriors to dismiss that process? That said, I also realized that a motorcycle helmet tear off plastic film and some rubber bands held stretched by fusible links would solve the problem just fine and at least double the life of the mission for negligible weight. It may not be glamorous or even guaranteed to be environmentally friendly, but it would work. Kind of like the old joke about NASA spending millions to design a space pen when the Soviets just used a pencil. So I'm afraid that there's still no way I can accept that the engineering isn't feasible. It just sets off my code smell detector too much. Planned obsolescence is perhaps a bit too strong of an accusation though, so I'm sorry for saying that.
- wolpoli 4y ago
barbazoo 4y ago
I dislike the Twitter UX so much, it's not clear to me if the "thread" only contains 2 tweets or if I'm too dumb to navigate this shitshow of a UI. Constantly being bombarded with popups doesn't help the UX either.
- coffeeblack 4y ago
  New Twitter will soon get long-form Tweets to address that problem. Amazing how in 15 years they never managed to fix this UX issue, despite have ten times more people than they actually needed.
  - mikewarot 4y ago
    The fact that tweets were short was a feature, not a bug. >Amazing how in 15 years they never managed to fix this UX issue, despite have ten times more people than they actually needed. It's not been established at all that this is the case. If they manage to keep things running without running afoul of consent decrees, etc. for a few years, then you might have a point.
- btgeekboy 4y ago
  It’s just the two below it. Beyond that are replies to the first message.
- snvzz 4y ago
  Nitter got you covered.
  - HWR_14 4y ago
    I thought Nitter stopped working sometime after Musk's takeover. Maybe just the specific mirror I used?
    - ancientworldnow 4y ago
      It still works fine, though it's largely dependent upon an api that may be retired.
billfor 4y ago
This makes wonder about solar roofs and efficiency over time. For example I don't see anything immediately obvious about how a Tesla Solar Roof might degrade over time due to dust and debris, but it stands to reason that it should. It seems like it should be easier to find this type of information on solar panels given the emphasis.
- rob74 4y ago
  Well, your solar roof won't be on Mars. Here on Earth, you have rain from time to time in most places. And even in the middle of a desert, you can simply wipe the panels clean once the dust storm has passed...
  - SoftTalker 4y ago
    Yeah, I'm not walking around on a pitched glass-surfaced roof that may be slimy with mold. Ever seen what a window eventually looks like in a humid climate if it hasn't been cleaned? Rain can wash off some surface dust but it doesn't really clean beyond that. Maybe this isn't as much of a problem in a desert.
superjan 4y ago
I asked about that recently in another thread. Besides the argument that you can just make the panels bigger, the dust is also statically charged so it is sticky, and wiping it off is not easy. It is also amusing that we, as programmers, are inclined to suggest adding MOVING PARTS to a system that is not servicable, and that the same problem can be solved just by adding more of an already proven solution. It sounds like this one clever special mitigation that solves a minor problem, but instead brings the system down.

prettyStandard 4y ago

They would rather contribute that cost&weight&complexity to just more solar cells. Got it.

logicallee 4y ago

After reading your note "why it's not possible for the solar panels to be self cleaned" I clicked through and as I clicked I was thinking "okay so obviously it is possible for the solar panels to self-clean. prove me wrong." I mean how hard could it be? No way is that an "impossible" task. I went out of it thinking, "yep, look at these excuses we are making for the state of robotics." - the quote is: "A system like that would have added cost, mass, and complexity. The simplest, most cost-effective way to meet my goals was to bring solar panels big enough to power my whole mission – which they did (and then some!)." So robotics is at the state where it is possible to send a rover to Mars, but a simple robotic arm can't easily brush off some dirt. The lander weighs 789 lb and the cost-effective solution is not try include a simple cheap lightweight robot arm that is foolproof and can easily sweep some dirt, because there is not such thing. Robotics isn't at the level where that is easy, cheap, or lightweight. If a human could reach through a portal to there with a brush, it would take less than five minutes to brush off the dirt that had fallen on solar cells. A simple, light, and foolproof robotic arm that can easily do that doesn't exist. Now that we have superhuman levels of general AI in chatgpt, isn't it time to work on foolproof and lightweight robot arms for all sorts of tasks?

gpderetta 4y ago
"A high resolution picture of the Insight Mars Rover on mars, with a simple, light weight and foolproof robotic arm brushing sand off its solar panels, in the style of Greg Rutkowski and Alphonse Mucha, 4k, trending on artstation"
blululu 4y ago
I would suspect that the problem is more difficult than you make it out to be. First, Mars is very windy/dusty. Second, there is no water so brushing dust is harder than on earth. Add in the increased static cling and dust ingress into the motors and it is not clear to me that brushing is actually viable on mars without a lot of extra engineering (and teams to figure all this out). I’m sure this decision was made with a good e evaluation since they did make the choice to add more panels which has its own downsides. There might even be some interesting papers out ther.
- m4rtink 4y ago
  What about compressing some of the atmosphere and then releasing it repeatedly from close proximity over the dusty panels? Given the very low atmosphereric pressure on Mars, a bit of gas at terrestrial sea level pressure equivalent would do wonders. As for downsides - you need a compressor and some filtering to avoid clogging your gas system with dust (thats likely the main obstacle). Still doable IMHO and I'm sure followup probes and eventually settlements will find how to handle Martian dust efficiently.
adamsmith143 4y ago
You did it, you solved RObotics! Someone get this guy a Nobel Prize!! JPL Engineers are no match for his staggering intellect!
Retric 4y ago
Most critically, other components are also failing so you don’t get that much more lifespan with unlimited power. A brush doesn’t work well in a zero moisture environment. The dust is horrifically abrasive and brushing it along the panels would cause damage. The added weight would have to be compensated for.
- m4rtink 4y ago
  Well, the MERs lasted quite a bit longer & were moving systems. A bit of a shame a static lander can't beat them. :P
  - Retric 4y ago
    Insight isn’t dead just hibernating which both MERs did several times. If Insight dies then Spirit will have lasted 50% longer and opportunity significantly longer, but both rovers lost quite a bit of functionality over time. So, the difference isn’t as stark as you might assume when you consider how much time rovers spent with reduced power or hibernating, stuck, etc.
nradov 4y ago
ChatGPT isn't general AI, not even close.
- logicallee 4y ago
  [1] Although ChatGPT might not meet some special elevated standards for what is considered general AI, it is able to solve a wide variety of generalized requests, including writing this response on command. In this sense, it is similar to SpaceX being a "real" rocket company, even though it is a private company with less experience than NASA. SpaceX has disrupted the traditional aerospace industry and demonstrated that it is capable of designing and launching successful space probes, despite not being a traditional "establishment" player. Another analogy might be to Uber, which has revolutionized the transportation industry by offering a new way of connecting riders with drivers through a smartphone app. Uber may not meet some traditional definitions of a "taxi company," but it has proven to be a successful and popular service for millions of people. A third analogy might be to the smartphone itself, which has become an essential tool for many people despite not being a traditional computer. Smartphones have disrupted the personal computing industry and offer a wide range of capabilities, from making phone calls and sending texts to accessing the internet and running apps. Similarly, ChatGPT is able to complete many general requests that meet the expectations of many users, even though it might not meet some definitions of general AI. It is able to do this because it is able to perform a wide range of tasks, including writing this comparison at your [my] request. Of course, ChatGPT has its limitations and is not a substitute for human intelligence. However, it is able to complete many tasks that would be challenging or impossible for chatbots of decades ago, which demonstrates its usefulness and capabilities as a tool for assisting users with a wide range of tasks. I hope this helps clarify my personal feelings about ChatGPT's intelligence and capabilities. It is important to recognize that different people have different standards and definitions for what constitutes general AI, and that is completely fine. What matters is whether a tool is able to meet the needs and expectations of its users, and ChatGPT has certainly been able to do that for me and many other users. -- [1] I want to clarify that this response was written by ChatGPT, a large language model trained by OpenAI, at my request. For more context on my request and the interaction with ChatGPT, you can view the full exchange at https://hastebin.com/raw/wolovegiqa https://hastebin.com/raw/wolovegiqa
ericbarrett 4y ago
I agree with you, and I think the other replies are missing your point. With all the techno-marvels around us, it's a shame that lightweight, reliable robotics that can do something as superficially simple as brush some panels don't exist. Just goes to show how hard the field is, I guess.
- logicallee 4y ago
  Yeah, they really don't get what I meant which is probably my failure to communicate. It's like me saying "It's a shame I can't save myself a few minutes every day by having a robot make my sandwiches for me, since there is no such thing as a cheap household robot that can easily make a sandwich from its ingredients put before it" and them saying, "nono there totally are they just cost too much so it doesn't make sense and you don't understand anything about the intrinsic difficulty of sandwich assembly in a zero-person environment". Okay fine but end result is I'm still making my own sandwich in 2022 :) End result is this mars rover can't do $2 worth of human work because it can't brush itself off, it is easier to add larger solar panels than brush them off since there's no such thing as a cheap lightweight easy reliable robot arm.
hn_throwaway_99 4y ago
This reply completely misses the point. All missions have an expected lifespan. The reason why they didn't use some sort of cleaning system is simply because it wasn't needed. The lander gathered all the data it was expected to, and then some. Why add complexity if it isn't useful?
- mturmon 4y ago
  ^-- This is the answer: this capability wasn't needed to fulfill science objectives. End of story. To add context: InSight was proposed to a cost-capped, competitive NASA program. Within competed programs, you can't spend money on nice-to-have's. You have to come in under a cost cap, while demonstrating you will achieve science objectives. Period. The science objectives are carefully time-bound by a very knowledgeable science team, and from those science requirements, all the engineering requirements, including lifetimes, are derived. InSight didn't need more than one Mars year for the science, so that's that. There were 2 instruments. In the case of the heat probe, they needed to observe at least one full annual heating cycle. For the seismograph, I think they had an approximate event rate and they needed to capture X number of events of a given magnitude to get insight (heh!) into the subsurface structure. Here's a description of how this works in general, from someone who was involved in InSight formulation and who is in the leadership of mission formulation at JPL: https://science.nasa.gov/science-red/s3fs-public/atoms/files/Launchpad_Session3_STM_18Nov2019_smf_final.pdf https://science.nasa.gov/science-red/s3fs-public/atoms/files... The whole presentation is great: the first introductory slides, some InSight examples, and the last 3 slides in particular give background on some of my claims above. The person who (with the PI, Bruce Banerdt) led the InSight "requirements trace" is Peg Frerking (https://scholar.google.com/citations?user=t6XZBAIAAAAJ&hl=en https://scholar.google.com/citations?user=t6XZBAIAAAAJ&hl=en), who is now a JPL fellow in part because of her work in adding engineering rigor to the formulation process. As this thread shows, it's very easy for clever engineers to add on nice-to-have's that are not required to meet science objectives. That's how you get overruns. Here's another recent HN reference point on capabilities that don't contribute to a great product: https://news.ycombinator.com/item?id=34032672 https://news.ycombinator.com/item?id=34032672 [Steve Jobs Insult Response]
- rob74 4y ago
funderbus 4y ago
This is more about "What are you willing to bet the mission on". The mission being a billions of dollars and years of effort. And mission success is defined as working for a limited time. In aerospace "simple" beats "slightly more complex but much better" often.

input_sh 4y ago

I don't see that thread claiming that it's not possible, just that it wasn't the most practical choice for this particular rover.

delecti 4y ago
It's possible for the solar panels on rovers to be self-cleaning, but it's not possible for the solar panels specifically on Insight to be self-cleaned.
grawp 4y ago
Insight is NOT a rover. It's stationary unmovable lander.

wazoox 4y ago

It's pretty amazing to think it still works with the panels as covered in dust as they are in the last frame!

jws 4y ago
Solar panel output is remarkably resilient to visible dirt. I have an installation on a seagull rookery. As you can imagine things get thoroughly “whitewashed”, especially since the top edge of the angled array is prime “standing around squawking and crapping” space. They can be covered to the point that there isn’t a clean spot the size of your fist anywhere on them and they will still be putting out 75% of their rated power. I suspect it has something to do with the non-linear response of the human eye. You don’t have to reflect a lot of light to be perceived as significantly lighter than black, so diverting 25% of the light from the panel to reflected light makes the panel look quite light.

ilyt 4y ago

So its essentially "the system needs to be cheap and light enough to beat bringing more panels"

dougmany 4y ago
I remember calculating the cost efficiency of adding a sun tracking mount to some panels. It turned out that the increased power would be about the same as adding an additional panel and one panel was cheaper than the mount. The mount also would only help half the year and the extra panel would help the whole year.
- implements 4y ago
  If your array is at ground level it still might be worth being able to manually adjust the mounting angle for different seasons (high sun / low sun).
- andrewflnr 4y ago
  But would the sun-tracking mount also let you shed dust buildup? That might make it worth it for long term missions. My next idea after blowers for removing dust was to just flip the panel vertical for a bit...
- ilyt 4y ago
  Well, till you run out of roof space.

MobileVet 4y ago

If only there was a simple mechanism, maybe a four bar linkage, with trillions of cycles of testing... it would have to be light weight and include some form of brush or wiper and function with significant forces applied, similar to wind from a moving vehicle... I guess the downside of having JPL in SoCal is that none of the engineers are familiar with windshield wipers. <jk>

adamsmith143 4y ago
"A system like that would have added cost, mass, and complexity. The simplest, most cost-effective way to meet my goals was to bring solar panels big enough to power my whole mission – which they did (and then some!)."
- MobileVet 4y ago
  It was a joke... simplicity is always best.

Communitivity 4y ago

I am seeing a lot of comments along the lines of 'windshield wipers?' Cars were invented in 1886, the first windshield wipers became available for them in 1917, 31 years later. That is... - in an environment with plenty of water - not near waterless, - on glass windshields (much less fragile than solar panels), - where we can physically replace the wipers when needed, - where we can adjust if they get stuck, - and where there is much less dust. If we add 5 years of R&D to overcome each of those obstacles (very optimistic, it's more like 10 well-funded years I suspect), then even optimistically we're looking at 25 years. I suspect we might have a rover with self-cleaning panels, or safe cold-fusion, in 25 years. I don't expect one this decade.

Mistletoe 4y ago
That’s the most bizarre math I’ve ever seen. Once you’ve designed something once it’s a lot faster to design over and over.
- Communitivity 4y ago
  Each one of those bullets is a different engineering problem. The math is based on real government R&D I've seen. "Once you’ve designed something once it’s a lot faster to design over and over". You forgot the last part of that sentence: Once you’ve designed something once it’s a lot faster to design over and over, if you are in a similar environment with somewhat similar conditions.
  - chasd00 4y ago
    > government R&D I've seen oh, now i understand the math
deleted 4y ago
[deleted]
hn_throwaway_99 4y ago
The tweet thread itself doesn't say that using self cleaning panels would be impossible, or even that hard, just that it's easier and more cost effective to just bring bigger panels. Not of your bullet points seem that relevant honestly - using an equivalent of a leaf blower would do the trick. But any added complexity to a mission just means there are more failure points.

photochemsyn 4y ago

Given the success of the helicopter drone (Ingenuity) on Mars, I wonder if that's an option for cleaning solar panels - i.e. put a simple rotating brush/fan system on the drone, keep it in a port on the main lander, and every once in a while, launch it and have it land on the solar panels, where it does a roomba routine. Since drones already expand the abilities of a lander, i.e. exploring the immediate area and collecting samples, this wouldn't be much of an added cost.

pbhjpbhj 4y ago
Or 'just' have a mini roomba on each panel?
kitd 4y ago
Or have the drone fly low over the panels, making use of the down-draught.

Mistletoe 4y ago

Who decided to anthropomorphize the rover like that? It’s creepy and honestly scientifically dishonest, like the rover has intelligence and is writing the posts. Something for children, but children hate being fooled like that and being talked down to. It’s something I might expect from the current version of NASA though.

brrwind 4y ago
It's... the twitter profile of the rover, it's not that big of a deal
Toutouxc 4y ago
I don't find it any more disturbing than buying car tires from the Michelin tire guy (he's actually called Bibendum) or getting batteries with the Duracell Bunny on them. Some people, even educated and technically inclined people, like their tech a little anthropomorphised.

JoeAltmaier 4y ago

Cant just use a pad on the arm to rub away at them?

Zancarius 4y ago
What happens when the pad gets choked out with dust?
- dredmorbius 4y ago
  Great Mars-dust-wiper pads have little Mars-dust-wiper pads upon their backs to wipe 'em. And little Mars-dust-wiper pads have lesser ... pads, and so ad infinitum. It's pad's all the way down.
- JoeAltmaier 4y ago
  Squeegee then. You get the idea.
c22 4y ago
Since we're throwing stuff at the wall how about flexible solar panels wrapped like a tank tread that roll past a stationary wiper arm?
andrewflnr 4y ago
I'd go with a brush, actually.

zackmorris 4y ago

I don't buy it. There are so many ways to solve the problem that wouldn't add significant weight, that there must be some ulterior motive. And there is. NASA plans obsolescence into the rovers to get funding to build the next rover.

nradov 4y ago
This type of arrogant, aggressive ignorance is really the worst part of HN. How many successful space probes have you designed? How much weight would the solution add, and what trade-offs would that impose on other mission parameters? NASA is by no means perfect. But we can start by assuming they have basic competence and positive intent unless proven otherwise.
- zackmorris 4y ago
  I'm not doubting their competence, they're the best of the best IMHO. But sometimes politics and economics overshadows the work.
  - zackmorris 4y ago
    Hey nradov after sleeping on it, I agree with you, I don't like the tone of my original comment. Probably every engineering team at NASA who was part of Insight had a say in whether to invest an ounce in a dust cleaner or another sensor, and they went with the sensor. Who are we armchair warriors to dismiss that process? That said, I also realized that a motorcycle helmet tear off plastic film and some rubber bands held stretched by fusible links would solve the problem just fine and at least double the life of the mission for negligible weight. It may not be glamorous or even guaranteed to be environmentally friendly, but it would work. Kind of like the old joke about NASA spending millions to design a space pen when the Soviets just used a pencil. So I'm afraid that there's still no way I can accept that the engineering isn't feasible. It just sets off my code smell detector too much. Planned obsolescence is perhaps a bit too strong of an accusation though, so I'm sorry for saying that.
wolpoli 4y ago

barbazoo 4y ago

I dislike the Twitter UX so much, it's not clear to me if the "thread" only contains 2 tweets or if I'm too dumb to navigate this shitshow of a UI. Constantly being bombarded with popups doesn't help the UX either.

coffeeblack 4y ago
New Twitter will soon get long-form Tweets to address that problem. Amazing how in 15 years they never managed to fix this UX issue, despite have ten times more people than they actually needed.
- mikewarot 4y ago
  The fact that tweets were short was a feature, not a bug. >Amazing how in 15 years they never managed to fix this UX issue, despite have ten times more people than they actually needed. It's not been established at all that this is the case. If they manage to keep things running without running afoul of consent decrees, etc. for a few years, then you might have a point.
btgeekboy 4y ago
It’s just the two below it. Beyond that are replies to the first message.
snvzz 4y ago
Nitter got you covered.
- HWR_14 4y ago
  I thought Nitter stopped working sometime after Musk's takeover. Maybe just the specific mirror I used?
  - ancientworldnow 4y ago
    It still works fine, though it's largely dependent upon an api that may be retired.

billfor 4y ago

This makes wonder about solar roofs and efficiency over time. For example I don't see anything immediately obvious about how a Tesla Solar Roof might degrade over time due to dust and debris, but it stands to reason that it should. It seems like it should be easier to find this type of information on solar panels given the emphasis.

rob74 4y ago
Well, your solar roof won't be on Mars. Here on Earth, you have rain from time to time in most places. And even in the middle of a desert, you can simply wipe the panels clean once the dust storm has passed...
- SoftTalker 4y ago
  Yeah, I'm not walking around on a pitched glass-surfaced roof that may be slimy with mold. Ever seen what a window eventually looks like in a humid climate if it hasn't been cleaned? Rain can wash off some surface dust but it doesn't really clean beyond that. Maybe this isn't as much of a problem in a desert.

superjan 4y ago

I asked about that recently in another thread. Besides the argument that you can just make the panels bigger, the dust is also statically charged so it is sticky, and wiping it off is not easy. It is also amusing that we, as programmers, are inclined to suggest adding MOVING PARTS to a system that is not servicable, and that the same problem can be solved just by adding more of an already proven solution. It sounds like this one clever special mitigation that solves a minor problem, but instead brings the system down.