It really is a shame the boffins couldn't work in a brush on a stick.
Not blaming them at all, I'm sure they thought of the problem.
It's just a shame they couldn't get one in.
Recent photos from NASA's Mars InSight lander demonstrate that even the Register readers' filthiest PCs cannot compare to the effects of Martian dust. Although consequences of poor PC hygiene can result in blocked fans, overheating silicon, and even the odd dried animal corpse, a build-up of dust on spacecraft solar panels can …
They did try a fan, once, but it turns out that the blades needed to spin really fast to blow a hole (in the dust). Alternatively, landing the drone on top of the lander's solar panels was determined too great a risk. It would have blown a mini-storm with a chance of rolling the lander on its side and no rain was expected to help.
I used to work at JPL. I can't stress enought how much weight is a premuin for these probes. If they were going to try to out something to blow dust off the panels, a systems analysis is likely to end up with some kind of spritzer using gas generated by a chemical reaction if the probe doesn't have some kind of copter than can perform other duties beyond dusting panels. Think modified maneuvering thruster. But that has its own issues. But dust management is obviously going to be a big deal for any long term Mars missions, especially manned missions where you have to maintain door seals.
An easier way would be to cover the solar panels with a transparent "balloon" type bag.
If dust builds up, inflate the "solar panel balloon bag" from a small expandable "storage balloon" which has been slightly pressurised and filled, via a small on-board pump, with clean, Martian atmospheric gas during a non-storm period).
Then simply open a valve from the "storage vessel" to inflate the "solar panel balloon" using the pressurised gas, and the dust should fall off. One could also statically charge said inflating gas with an opposing electric charge which might help repel any residual dust.
Cost: 2 bespoke balloons, a pump, a couple of valves and a small static charge anode.
Cost: 2 bespoke balloons, a pump, a couple of valves and a small static charge anode.
plus the fuel to get the additional mass out of earth's gravity well, plus more fuel for course changes en-route due to increased inertia, plus whatever is required to get that additional mass safely to the surface of Mars...
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"plus the fuel to get the additional mass out of earth's gravity well, plus more fuel for course changes en-route due to increased inertia, plus whatever is required to get that additional mass safely to the surface of Mars..."
The InSight landed mass is 358 kg.
My suggestion for 2x balloons big enough to cover the 2x 2.15m (dia) solar panels with a thin expandable sealed covering, using maybe a thin polythene might add a few tens of grammes, same with a storage balloon - and a small pump and a valve (and some thin plastic tubing) might add maybe 50-75 grammes. So, perhaps 150g (6 oz) in total.
In the big scheme of things that's a minor sacrifice compared to being able to extend the mission by perhaps months or years?
There is also the issue that having packed them away the lander would have to survive solely on battery power until the storm stopped and the dust settled, and then still have enough power to open the panels again ..... against the drag of the dust that has dettled into the open/close mechanism.
One of the challenges in exploring the moon or planets is dust kicked up by engines during landing or activity on these distant worlds. Scientists in the Electrostatics and Surface Physics Laboratory at NASA's Kennedy Space Center in Florida are developing ways to mitigate this problem.
Electrodynamic dust shield, or EDS, technology is based on concepts originally developed by NASA as early as 1967 ...
A techy paper titled History and Flight Devleopment of the Electrodynamic Dust Shield is available here:
If your preferred article style is more newsy than techy, the BBC reported (23 Aug 2010) that "Working with Nasa, Malay Mazumder from Boston University originally developed the technology to keep solar panels powering Mars rovers clean." and that "They expect the technology to be commercially available within one year."
I always thought something like those peel of clear covers you can get for bike helmets could be used here somehow. The sort once covered in mud/dust, can just be peeled of to give you a clear screen again.
Wouldn't really work with the flip out segmented panels in use here, at least not easily, but aught to be easier for a square/rectangular PV panel.
You'd have several thin clear layers of something, over the PV panel. And as dust accumulates, you basically peel one off. So nice clean surface again.
I see two issues, one how to do the peeling, and two what happens to the peeled off layer, don't want that gumming up the wheels , or other instruments for example.
My though would be to have a thin piece of sprung metal (or other suitable material), that's wants to curly up like a watch spring, but is pulled out flat under tension, and you have one of these in parallel either side of the panel, fixed directly to the clear sheet. (i.e. spring-sheet-spring).
Hard fix one end of the 'spring' to one end of the panel, but the other end of the spring is on a release mechanism, perhaps a simple slide, clamping the spring down, that you pull back, and so release the end of the spring.
So we now have a panel, with a clear sheets 'stuck' to the panel, and the sheet is attached two metal springs, pulled flat so under tension, down two sides of the sheet. Fixed at one end, release mechanism the other end.
Panel gets too dirty, release the springs each side. These try to return to their coiled up state, so peel off the clear layer, revealing a nice fresh clean layer underneath.
As this naturally curls up, this also traps the dust that was on the panel inside the roll of the sheet, so reducing the risk of the dust dropping back on the panel. And as the other end of the springs were fixed. This means that the peeled sheet, is now basically a roll-up on one side of the panel, so won't drop anywhere you don't want it to, like the wheels etc.
You could have multiple layers quite easily. Just sit them layered over each other, and the release system just has to do one sheet at a time. So a simple slide release would work, as you just make the release end of the springs, shorter on the top layer, getting longer as you go down the layers.
I can't imaging the clear sheets and springs would be very heavy, although the release system might need perhaps a small motor to mange this. Doesn't even need to be powerful if it used a small reducing worm gear or similar, to increase torque at the expense of speed.
Granted you'd eventually run out of sheets, but I'd imagine just 3 or 4 would be enough for a typical extended rover/lander mission.
Just a thought anyway!
If instead of horizontal panels the panels were tilted up about 60 degrees then the majority of the dust would just fall off the panels.
There would obviously be an efficiency penalty (which would translate into a weight penalty) as bigger panels would be needed).
Alternatively the solar panels could be mounted on the end of an arm that could be rotated to dump the dust off when needed.
Icon for the dirty solar panels ============>
Many years back I knew of a local building supplies company where the sales office was inside a large wooden hut. Sat upon the big desk inside the terminals / cash registers were continually put upon by a barrage of plaster, sand, cement dust and fine grit etc. I kid you not each one of them looked ten times as bad as the probe in the photo does and yet, somehow, they continued to operate. I can therefore only assume that someone at the company either had the good foresight to order Mil-Grade equipment, or that maybe they were in fact conducting tests for NASA.
Well, it's not _that_ irrational. It's a fairly big chunk of plutonium, it's really radioactive (*) and, if your launch vehicle should explode, it will get spread over a very large area - which is considered a bit anti-social. Also the reactors used to make it tended to be "military themed" and really expensive to operate. Generally the world's militaries/governments are a bit less into plutonium weaponry than they used to be (probably a good thing) so supplies for RTGs would get way more expensive if they were having to fund the full reactor operations rather than just taking a few trimmings off the side.
Some other details here: https://spacenews.com/plutonium-supply-for-nasa-missions-faces-long-term-challenges/
(*) - although, if I recall correctly, the alpha particles will get you way before being poisoned. Perhaps I was also thinking of the horrific chemical processing that also needs to be done?
I wonder if needles with high voltage AC could bleed some charge out of the dust. It might suck up a precious 20W or so but maybe it only needs to run for a few seconds after a dust storm so that the dust can be shaken off.
The self-cleaning reflectors along roads are brilliant but I suspect that wind powered brushes are more like wind powered grinders on Mars.