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-...
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.
At the end of the day the best way to ensure mission success is to put the mission first, not future missions, not "nice to haves", put every dollar you have into making the prescribed mission as perfect as possible. You're suggesting the equivalent of "Navy SEALs sometimes get caught in larger than expected firefights, so each man should lug an extra 1000 rounds of spare ammo into combat just in case". And they could, but that would slow them down and endanger the immediate mission, even if only slightly.
The opportunity cost of that million dollars could be that testing is slightly less extensive and that a minor flaw goes undetected, or other work is rushed because the engineers were busy getting the wipers to work properly. It could also be that there's no interesting science to do in that area even with an extended mission, so the mission extension turns out to be completely worthless.
It's a different mindset than most engineers are used to, because we're used to users having vague desires and needs that even when well defined are somewhat ambiguous, so we plan generic solutions for a bunch of different edge cases and assume things will be used in ways other than what they're intended. And we all like building durable stuff that lasts the test of time. But when you're building a missile you don't care about minor memory leaks, and these probes are essentially science-missiles.
>At the end of the day the best way to ensure mission success is to put the mission first, not future missions, not "nice to haves", put every dollar you have into making the prescribed mission as perfect as possible. You're suggesting the equivalent of "Navy SEALs sometimes get caught in larger than expected firefights, so each man should lug an extra 1000 rounds of spare ammo into combat just in case". And they could, but that would slow them down and endanger the immediate mission, even if only slightly.
That's a massive exaggeration. I am not advocating for a contingency to every possible failure mode. I am pointing out that we clearly have one very common failure mode that can be solved and likely get us far more utility for little investment.
If you are going to compare it to Navy Seals, what I am suggesting is more akin to "Navy Seals can get shot. That's not good and these are highly trained specialists that don't grow on trees, we should probably give them body armor to give them a chance to survive being shot." And we do give them body armor. Yes it adds weight. Yes it costs more money. But more come home to complete more missions.
Yes a mechanical solution to remove dust from panels adds weight and cost but it can be the difference between an otherwise functional probe dying one day due to low power or dying years later once its electronics fail.
And yes, the most expensive part is designing and building the probe, that includes designing purely custom wipers/vibrators/whatever, hardening them for space so they survive the journey, testing and iterating them in Mars-like and space-like conditions, all on a limited budget that has to build the rest of the probe to the same exacting standards, all for the possibility that there's something outside of the mission scope worth doing. Intuitively wipers and vibrators seem like cheap commodity hardware because we have them everywhere and economies of scale to support them, so why not slap them on? But that doesn't apply to bespoke things like Mars Rovers.
There are constraints your analysis is not taking into account, there's likely also internal NASA constraints that neither of us know about. It's an appeal to authority, but I'm going to assume the engineers at NASA JPL who have decades of experience building/launching/landing Mars rovers have considered the tradeoffs of wipers/dust removal mechanisms for this specific mission.
If you're asking why they don't add them I've provided some speculative reasoning based on my experience in adjacent industries. If you're arguing that they missed an obvious design flaw and you know how to build a better Mars rover, within their constraints, maybe, but given NASA JPL's track record I have my doubts.
See, I don't see it that way. You didn't state it as "here are some possible reasons". You formed your argument as "this is why what you are proposing is wrong". Without actually being an authority on it and knowing if that's true.
Neither am I. But we should be able to discuss hypotheticals and come up with ideas as to possible solutions and their drawbacks. I'm sure there are very good reasons why they don't include them. But, having worked in the aerospace industry although nothing to do with NASA or spaceprobes, I find arguments about budget or building just to the mission unsatisfactory. I'm pretty sure there is an engineering challenge that makes it unworkable or unpractical and you and I are just ignorant to it.
There are obvious benefits to the ability to clean solar panels on Mars. And Space probes tend to be more over engineered than people give them credit for. Yes they are built to extreme margins to optimize capability for low weight. But that capability is great. We are talking about the same engineers who replaced the perfectly workable airbag solution for the skycrane which was far more complicated a solution because it promised to land the vehicle softer and give it a better chance of making it to surface unbroken.
So I can only conclude that there is some kind of engineering problem that prevents it. Maybe Mars dust is more like Moon dust that dirt on Earth and its akin to tiny razors? Brushing it off could damage the solar panels.
That's just me spitballing.
Thus scratching the delicate surfaces of the panels, as well as requiring a retraction motor and associated devices that have their own failure modes.
What I do buy is that panelshaking of this sort uses energy that would be in short supply if the panels are sufficiently blocked to require it. That doesn't seem impossible to solve, either, but I don't blame NASA for not feeling the need to solve it when they already designed and built InSight to exceed its mission parameters.
(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 ?
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.
The reason engineering exists is to be useful: to create artifacts and technology to make our lives better, easier, etc.
But science only has three uses: to inform engineering; to satisfy our human curiosity; and to beget more science. Any "usefulness" here is of a very narrow scope. I don't mean to say that it's not important, but that's not the same as being useful.
If I try to look at what the Insight lander accomplished, for instance, I find articles claiming that Insight found that the core of the Mars was much larger than previously thought. Let's leave aside whether the exact size of Mars' core is important or not. If I look for estimates of the size of the core prior to Insight, they're all in line with the estimates that came from the Insight data. From what I can see Insight brought the range of estimates closer together, but it seems to be about what people were expecting beforehand.
For those looking to keep a job in sciences, begetting more science sounds pretty darn useful
In the same way, any single 'act of science' can be hard to measure. They enable some experiments, which allow us to test some hypothesis. In some cases it is simple enough to point out when it is testing hypothesis that end up benefitting humanity, but that's only part of the effect. Many times a hypothesis is either rejected or fails to be rejected and slightly influences a larger theory which in turn is used to create new hypothesis. This creates a circular reference until some time later we end up with a theory that is useful for improving humanity. But which hypothesis were actually pivotal to forming the theory? Which acts of science allowed testing a hypothesis and receiving a clear enough failure that future effort was reallocated to other, eventually more fruitful, areas? Other than trivial cases, the cause and effect becomes such a tangled web we can't be sure.
You even have the publicity side. Where sometimes the effect isn't directly contributing to the theory, but engaging more attention to a field which leads to more children choosing the route of becoming a scientist.
Math has a similar issue. Much of pure mathematics has no known or foreseeable application. Yet, we can look back at what math does have very useful applications and see how many times the math predated the application being found, sometimes by long enough gaps that those who discovered the tools never saw them to be applied.
If someone has no idea what research will yield results, and has no preference for what research gets funded, that's fine. But if all research is the same to them, they should probably let those who view certain research as more important than others to make the decisions about what gets funded.
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
[1] Moon, but similar: https://youtu.be/0k9wIsKKgqo?t=378
Edit: huh, apparently it is one-time use and does not loop around.
https://www.sciencealert.com/nasa-s-insight-lander-enters-hi...
Yes, it’s short sighted but unfortunately a result of extreme budget constraints.
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.
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
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.
Can someone enlighten me?