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I'm confused on why the end state for all these rovers is to loose power because of dust on the solar cells. They did such a good job engineering these things

• rwmj 4y ago
  Some kind of passive self-cleaning solar-cell cover might work. You could direct and shape the wind so it blows more strongly over the cell surface to clean it, or since the dust is charged[1] you might use a conductive layer with the same charge. (Although I'm sure engineers have thought long and hard about this already.) [1] Moon, but similar: https://youtu.be/0k9wIsKKgqo?t=378 https://youtu.be/0k9wIsKKgqo?t=378
  • blululu 4y ago
    The static charges necessarily come in pairs so the dust is charged both positive and negative, but the surface also gets charged as dust hits it so trying to blow it off does not necessarily work in the long term. Static dust is a real pain in a low water environment.
  • rzzzt 4y ago
    An infinite loop of transparent film, similar to what the in-car F1 cameras have? Edit: huh, apparently it is one-time use and does not loop around.
• bamboozled 4y ago
  Windshield wipers add weight and complexity but more importantly add to the budget. These things are designed only to serve the mission. This rover was designed to last 1 year and went for 4 so it’s a pretty good result. Some good discussion here [1] on Astronomy Cast regarding this topic and potential solutions NASA is working on. Such as an electrostatic dust blaster. 1. https://podcasts.apple.com/vu/podcast/astronomy-cast-ep-661-looking-back-on-the-missions/id191636169?i=1000588935991 https://podcasts.apple.com/vu/podcast/astronomy-cast-ep-661-...
  • brnt 4y ago
    They add weight, but also may extend the mission, meaning for science for buck. NASA rovers outlast their no doubt conservatively estimated life expectancy consistently.
    • wongarsu 4y ago
      Well, you give a mission plan of one year, and design a rover to fit that plan. And because you don't want to fail, you engineer everything to have a tiny failure rate in the first year. That also makes the systems likely to work for many more years, but that's just a side effect. You have only explicitly designed and spent money on that first year. Taking funding from that first year to add a system that only becomes useful in year three is a completely different matter, and likely much harder to greenlight.
      • ansible 4y ago
        Also, something not explicitly stated in this thread is that most of the most important science happens in the first year the rover / lander is there on Mars. You really want that first year to be successful, and anything beyond that is bonus.
      • brnt 4y ago
        Sure, but you also learn from experience. If it turns out dust on panels is usually the limiting factor, and the rover otherwise stay in good shape well beyond expectations, a mitigation for the dust may be an effective solution in reliably operation lifetime and thus mission scope.
    • Retric 4y ago
      Every component runs into issues, look at how many rover’s wheels had issues before the panels failed.
  • thereddaikon 4y ago
    Seems a bit shortsighted to me. Given that if they avoid a catastrophic failure before landing these things seems to consistently last beyond the originally planned mission, they should be building them with mission extensions in mind. Not putting all your eggs in one basket of course. Shit happens and probes are still lost even today. But a simple device to remove dust such as a vibration function, a small blower fan or something else seems to be a major value add. Even if it costs $1 million extra to do, it costs far more to build the rover and send it there so you are still saving money.
• jacquesm 4y ago
  (1) they were intended to last for three months and (2) dust is extremely static and there is no really good way there to get rid of this static charge, (3) dust is pretty sharp ('abrasive') and will scratch the surface of the cells if removed mechanically.
  • piva00 4y ago
    I assume that a system such as the self-cleaning of camera sensors by vibration wouldn't work either due to the static charges then, correct?
  • danw1979 4y ago
    Regarding (1), almost all of these Mars robots seem to do useful science well beyond the end of the stated mission, I think the OP was suggesting that maybe it’s time we start trying out solutions for much longer duration missions ? (2) - could it be possible to introduce an oppositely static charged layer on the panel surface to repel dust to stop it settling in the first place ?
    • bluGill 4y ago
      Every part needs to last 3 months. If even one part breaks after 2 months the whole thing failed. Each part increases the odds that one will break after 2 months. The only way to work around this is to design each part to last for 5 years, that way the odds are high that all parts survive for the required 3 months. It also means that odds are reasonable the rover will work for much longer than 3 months, and in many cases you can operate in a degraded state for a even longer.
    • bnralt 4y ago
      > almost all of these Mars robots seem to do useful science well beyond the end of the stated mission How are we defining "useful science" here? They all do some kind of scientific investigations, but it's hard to say if it's useful or not. If you look at coverage or discussions about the lander (including here), people get very excited about the landings, and somewhat excited about the pictures. The science almost never gets discussed. Even when NASA tries to hype it up, it seems the most important stuff they have is continually telling us they found Mars has some water and used to be wet, and that there's the possibility there once was life on Mars. People seem enamored with the idea that we're sending things to Mars and doing "something." But there doesn't seem to be a lot of concern about what that "something" actually is.
• hawski 4y ago
  I am sure it comes down to economics really, but I do wonder now about a mission in far future, that would clean solar panels of all those older missions to make them work again. For shits and giggles I guess.
  • phone8675309 4y ago
    IIRC this was a plot point in The Martian
    • hawski 4y ago
      Oh, yes indeed. I forgot about that.
  • danw1979 4y ago
    Like a long range Ingenuity helicopter that cruised the planet using its downwash to revive old rovers ?
    • phpnode 4y ago
      This idea gets brought up in every thread about Insight's dust issues - there is not enough air pressure on Mars for the downwash to clean the panels. For Ingenuity specifically the problem is that it is also far too far away - it would take over ten years for the chopper to reach Insight.
    • dwringer 4y ago
      After a few months I can't even blow all the dust off surfaces in my apartment. I can only imagine years outside on Mars.
    • timdiggerm 4y ago
      Don't underestimate the size of a planet
  • bluGill 4y ago
    It might be fun to try, but realistically, without heat, thermo issues will ensure that even if you did this the rovers wouldn't work anymore.
• jvanderbot 4y ago
  Dust is a factor, but so is cold and diminishing solar. My guess is that the dust isnt a problem until late in the season, and by then they hope to have gotten all the data they came for. IIRC, one of the reasons the MER rovers lasted so much longer is the dust clearance from wind, which was much more than expected. Perhaps Insight counted on more clearing than they got. I'd just go ask their Project Scientist on Twitter. @MarkPanning
• yummypaint 4y ago
  I once (around 2010) worked with a nasa designed system for electrically clearing solar panels. It was basically a 3-phase arrangement of transparent indium tin oxide electrodes on the surface of the panels. By supplying high voltage AC, both conductive and insulating particles can be removed by various mechanisms. I thought it worked quite well and keep expecting to see it in the wild somewhere. Maybe it's still in the pipeline somewhere.
• deleted 4y ago
  [deleted]
• theandrewbailey 4y ago
  Spirit and Opportunity lasted for much longer (6 and 14 years, respectively), aided by periodic winds that blew dust off the solar panels. It appears that Insight's location doesn't receive many of these compared to others. https://www.sciencealert.com/nasa-s-insight-lander-enters-hibernation-as-dust-puts-it-at-risk-of-an-energy-crisis https://www.sciencealert.com/nasa-s-insight-lander-enters-hi...
  • grawp 4y ago
    Spirit and Opportunity were rovers and constantly changing place and position. Insight is NOT a rover. It is an unmovable lander.
• arriu 4y ago
  Same reason the rockets NASA uses are not reusable. It’s not part of the mission. Yes, it’s short sighted but unfortunately a result of extreme budget constraints.
• mhb 4y ago
  Oliver Wendell Holmes can (http://holyjoe.org/poetry/holmes1.htm http://holyjoe.org/poetry/holmes1.htm): The Deacon’s Masterpiece or, the Wonderful "One-hoss Shay": A Logical Story Have you heard of the wonderful one-hoss shay, That was built in such a logical way It ran a hundred years to a day, And then, of a sudden, it — ah, but stay, I’ll tell you what happened without delay, Scaring the parson into fits, Frightening people out of their wits, — Have you ever heard of that, I say? Seventeen hundred and fifty-five. Georgius Secundus was then alive, — Snuffy old drone from the German hive. That was the year when Lisbon-town Saw the earth open and gulp her down, And Braddock’s army was done so brown, Left without a scalp to its crown. It was on the terrible Earthquake-day That the Deacon finished the one-hoss shay. Now in building of chaises, I tell you what, There is always somewhere a weakest spot, — In hub, tire, felloe, in spring or thill, In panel, or crossbar, or floor, or sill, In screw, bolt, thoroughbrace, — lurking still, Find it somewhere you must and will, — Above or below, or within or without, — And that’s the reason, beyond a doubt, A chaise breaks down, but doesn’t wear out. But the Deacon swore (as Deacons do, With an “I dew vum,” or an “I tell yeou”) He would build one shay to beat the taown ’N’ the keounty ’n’ all the kentry raoun’; It should be so built that it couldn’ break daown: “Fur,” said the Deacon, “’tis mighty plain Thut the weakes’ place mus’ stan’ the strain; ’N’ the way t’ fix it, uz I maintain, Is only jest T’ make that place uz strong uz the rest.” So the Deacon inquired of the village folk Where he could find the strongest oak, That couldn’t be split nor bent nor broke, — That was for spokes and floor and sills; He sent for lancewood to make the thills; The crossbars were ash, from the straightest trees, The panels of white-wood, that cuts like cheese, But lasts like iron for things like these; The hubs of logs from the “Settler’s ellum,” — Last of its timber, — they couldn’t sell ’em, Never an axe had seen their chips, And the wedges flew from between their lips, Their blunt ends frizzled like celery-tips; Step and prop-iron, bolt and screw, Spring, tire, axle, and linchpin too, Steel of the finest, bright and blue; Thoroughbrace bison-skin, thick and wide; Boot, top, dasher, from tough old hide Found in the pit when the tanner died. That was the way he “put her through.” “There!” said the Deacon, “naow she’ll dew!” Do! I tell you, I rather guess She was a wonder, and nothing less! Colts grew horses, beards turned gray, Deacon and deaconess dropped away, Children and grandchildren — where were they? But there stood the stout old one-hoss shay As fresh as on Lisbon-earthquake-day! EIGHTEEN HUNDRED; — it came and found The Deacon’s masterpiece strong and sound. Eighteen hundred increased by ten; — “Hahnsum kerridge” they called it then. Eighteen hundred and twenty came; — Running as usual; much the same. Thirty and forty at last arrive, And then come fifty, and FIFTY-FIVE. Little of all we value here Wakes on the morn of its hundreth year Without both feeling and looking queer. In fact, there’s nothing that keeps its youth, So far as I know, but a tree and truth. (This is a moral that runs at large; Take it. — You’re welcome. — No extra charge.) FIRST OF NOVEMBER, — the Earthquake-day, — There are traces of age in the one-hoss shay, A general flavor of mild decay, But nothing local, as one may say. There couldn’t be, — for the Deacon’s art Had made it so like in every part That there wasn’t a chance for one to start. For the wheels were just as strong as the thills, And the floor was just as strong as the sills, And the panels just as strong as the floor, And the whipple-tree neither less nor more, And the back crossbar as strong as the fore, And spring and axle and hub encore. And yet, as a whole, it is past a doubt In another hour it will be worn out! First of November, ’Fifty-five! This morning the parson takes a drive. Now, small boys, get out of the way! Here comes the wonderful one-hoss shay, Drawn by a rat-tailed, ewe-necked bay. “Huddup!” said the parson. — Off went they. The parson was working his Sunday’s text, — Had got to fifthly, and stopped perplexed At what the — Moses — was coming next. All at once the horse stood still, Close by the meet’n’-house on the hill. First a shiver, and then a thrill, Then something decidedly like a spill, — And the parson was sitting upon a rock, At half past nine by the meet’n-house clock, — Just the hour of the Earthquake shock! What do you think the parson found, When he got up and stared around? The poor old chaise in a heap or mound, As if it had been to the mill and ground! You see, of course, if you’re not a dunce, How it went to pieces all at once, — All at once, and nothing first, — Just as bubbles do when they burst. End of the wonderful one-hoss shay. Logic is logic. That’s all I say.
• idlewords 4y ago
  They gave Curiosity and Perserverance a plutonium power source to avoid this issue. My experience with "why don't they just X" for space stuff is that there's almost always a technical paper on it. This looks like a comprehensive review of different approaches to cleaning solar panels on rovers: "Cleaning Mechanisms for Solar Panels of Rovers and Other Extraterrestrial Unmanned Vehicles" https://doi.org/10.2514/6.2019-3452 https://doi.org/10.2514/6.2019-3452
• Baeocystin 4y ago
  It costs a lot of time and money simply to keep a mission operating, and these are scarce resources that need to be used for every active mission, old or new. Missions are thus planned for very specific lifetimes. On an organizational level, missions that live too long past their due date cause a lot of problems, too. This isn't cynicism- it's just the reality of trying to absolutely maximize the science return per scarce dollar spent. I personally would love it if ultimate lifespan was a feasible goal for every mission. So would pretty much everyone! But it isn't.