EEVblog #846 - Solar Panel Micrometeorite Impact!

[TheAmmoniacal]

Is the back panel a steel plate?

[Muttley Snickers]

A shattered ball bearing fired from a slingshot may aslo give similar results as any small particles left would have surface corrosion by now, also it appears that a guyed antenna mast is in close proximity so bird droppings washing into the crater can't be ruled out either.

[Brumby]

No.


But I am now ....

[Muttley Snickers]

Did anyone else think of the movie "The Andromeda Strain" whilst watching this?

Bugger.....

I just read the plot and was hoping for an early night, I will put the kettle on.....

[HAL-42b]

Seems like our layman classification of 'micrometeorite' is wrong. Look at the plain Meteorite page on Wikipedia.


Meteorite




Impact on a roof shingle (different impactor, not the one above)

[necessaryevil]

Dave, you said 'mine gets shattered...errrm.. hit roughly every year". But you calculated that your panel gets hit rougly every day. Did you mean to say that? The other alternative is that you meant 'shattered every year'. But that seems unlikey to me...

[Fungus]

A shattered ball bearing fired from a slingshot may aslo give similar results

Ball bearings don't shatter.

[Tek_TDS220]

A mass spectrometer won't help.  I think you need an instrument that does 'atomic absorption' (or AA) to find elements like iron, or better, SEM (scanning electron microscopy) with EDX (can scan and determine elemental composition).  The University of Sydney may have one. If you find iron and perhaps manganese, you'll have substantial evidence for a meteorite.

Given that the panel still works, I guess the surface film has not been broken?

[cdev]

One explanation might be uneven heating.

 A brand new glass door in the Berkeley hills, overlooking the Golden Gate was heated in the afternoon by the rays of the sun and spontaneously shattered while I and several other people were having lunch right next to it. the transition from smooth glass to shattered sheet was almost instantaneous.

It started with a single crack but the cracks spread through the entire thing in less than a second, with no external force being applied at all. Suddenly there was a strange crackling sound, and "zap" the safety glass door had turned into what I call "urban crystals"  i.e. broken glass.

That's one possibility. I made another post on another, which I think is perhaps just as likely. Ice from an airliner's toilet tank.

You could verify how common that is using electronics. (an RTLSDR) Your investigation would make a good video, even though its been covered elsewhere.

You might want to find Balint Seeber's original videos on ADSB which include some info on ACARS. Thats where I first read about this.

[Fungus]

A mass spectrometer won't help.  I think you need an instrument that does 'atomic absorption' ...

 If you find iron ... you'll have substantial evidence for a meteorite.

Or ... you could try a big magnet!

* Put a piece of clean paper over the hole.
* Apply huge magnet.
* Turn over and look at paper with microscope.


(paper is there because huge-ass magnets usually have all sorts of dirt stuck to them)

[dr.diesel]

I'd say don't screw with it.  Dave likely has enough popularity to get professional help, hate to disrupt what's left of the sample too much.

[mikerj]

But the best explanation I can come up with is one I saw happen before my very eyes.

 A brand new glass door in the Berkeley hills, overlooking the Golden Gate was heated in the afternoon by the rays of the sun and SPONTANEOUSLY DELAMINATED in less than a second, with no external force being applied at all. It was likely the uneven heating by the sun which did it. One side was hot - very hot, the other cool. Suddenly there was a strange crackling sound, and "zap" the safety glass door had turned into what I call "urban crystals"  i.e. broken glass.  Needless to say the vendor replaced it at no cost.

Something to think about, Dave, as Australia has a reputation for STRONG sunshine and cool people..

The fracture pattern and the big dent in the back of the panel are pretty much conclusive of an impact rather than temperature induced stress.

[G7PSK]

Having seen those microscope images I am now of the opinion that it was a cricket ball. I think it hit seam first and that it was an old one which had picked up grit which had become embedded in to the leather outer thus giving the sharp penetrating point. Also it was travelling upwards towards the roof hit the panel and continued onwards over the ridge and would have landed somewhere on the other side of the house from that on which the panel was mounted which is why when Dave looked in the gutter and on the ground underneath he did not find ant thing the seam depressing the glass and silicon would make the dent and the outer of the ball would be the ring in the break pattern. The brown bits in the glass would be leather particles.

[cdev]

They look like red or brown specks..  maybe it was frozen fecal matter from an airliner's toilet. (from airliner toilet ice)

How often might iced poop fall from airliners? A lot! A real lot.

David Taylor in the UK  ( http://www.satsignal.eu/raspberry-pi/acars-decoder.html ) and Balint Seeber (Youtube user balint256)  ( http://www.spench.net ) have both done a good job of explaining how to use a $12 USB DVB-T dongle to receive various kinds of telemetry, including ACARS, the airliner to ground messaging system.

I suspect that the damage may have been caused by poop from the sky and the plausibility of that theory likely can be shown easily in a way that is interesting and likely to give them a new tool to explore RF and electronics with.

You could use the free ACARSDEC software to decode it  -  http://sourceforge.net/projects/acarsdec/

A few days of ACARS I think is likely to show that airliners often send urgent messages to their hangar staff about the need for a servicing to remove waste from overflowing toilet tanks.


https://www.youtube.com/results?search_query=ACARS

https://www.google.com/search?q=ACARS+RTL2832

Try it..   

http://sdr.osmocom.org/trac/wiki/rtl-sdr  (source for the drivers and long list of known apps)

http://sdr.osmocom.org/trac/wiki/GrOsmoSDR#KnownApps (The needed hook to gnuradio - i.e. "gnuradio source block" and more apps)

http://sourceforge.net/projects/acarsdec/ ( "ACARSDEC" program )

Images tell a story faster than words can.

https://www.google.com/search?q=ACARS+decoder+SDR&source=lnms&tbm=isch

-----------

The "mid sized" R820T one pictured at the bottom here is a solid performer and its dirt cheap.:

http://goughlui.com/2013/12/12/more-rtl2832u-tuners-full-size-fc0013-mid-size-r820t/ 

The one with the curved row of holes.
The postage stamp sized square PCB lends itself to removal and use in other projects as an IF stage. Its stable and sensitive.









  (Link to bigger image: http://cdn1.goughlui.com/wp-content/uploads/2013/12/DSC_1111.jpg )


( Link to bigger: http://cdn1.goughlui.com/wp-content/uploads/2013/12/DSC_1112.jpg )

Use a different antenna. This one works quite well.

http://www.wa5vjb.com/references/PlanarDiskAntennas.pdf

[Lightages]

It was most definitely not a "micrometeorite". Any meteorite small enough to not punch a hole through your house would be traveling at terminal velocity of around 300kph by the time it gets to the ground. The impact crater you have in your panel could indicate an iron-nickel meteorite of something around 50 grams or more traveling at terminal velocity. It could also indicate the same size part or debris falling from a plane. Meteorites can have sharp points as well as can blue ice.

The debris you found in your microscope investigation is most likely a mix of random air particulates that fell over time, and in rain drops, along with many micrometeorites. You can collect 1 or 2 micrometeorites per every couple of days just by leaving a sheet of A4 paper outside and collecting the dust that accumulates. The reason you see these particles  in the shattered glass is because they were trapped there by the topology.

Sorry, not a micrometeorite, but still could be a 50+ gram or so stony meteorite or iron-nickel meteorite. Something that small (2-3 cm) could escape detection easily enough. Being so close to an airport makes the likelihood much higher of it being debris from a plane.

[Rog520]

Had the very same thing happen to one of my solar panels a few years ago. Mine are all pole mounted, about six feet off of the ground, for an array that stretches out about 80 feet. All sorts of possibilities went through my mind (things falling from the sky via airplane seemed the most plausible at the time for some reason  ), but I came to the conclusion that it must've been a rock thrown by the lawnmower. After all, I WAS mowing the area just two days prior. Still, the angle of impact appeared to suggest something coming from above. And it was forceful enough that it went right through the glass, through one of the cells, and left a large dimple in the laminate on the back of the panel. Couldn't find anything near the panel that I would've considered the projectile, though. Not even a suitable rock. I guess it will always remain a mystery. And hopefully a one-time event! I know I'll never be mowing near the panels again!

[Stonent]

You could potentially collect the particles with a coffee filter over a vacuum cleaner hose.

[Stonent]

If only LG had made their panels out of Solar Freakin' Roadways. They can hold a tractor.

[Nerull]

Right, micrometeorite has a scientific definition, and its a particle under 2mm - you will never see one of these impacting with any force on the ground. Most don't survive reentry at all, and those that do drift down slowly as particles of dust. The vast majority of meteors will slow to terminal velocity well before impact - only those over about 10 tons will retain any of their velocity by the time they make it to the ground. If a 10 ton meteorite hit your house, you wouldn't have a house anymore.

Most likely, if it was a meteor, you're looking at something in the golf ball to baseball/cricket ball maybe up to softball size, which impacted at terminal velocity, bounced off, and is sitting on the ground somewhere nearby.

Now, an dense object of that size can do considerable damage at terminal velocity, but its not the hollywood special effect sort of impact people imagine, and its no more damage than the same object dropped from an airplane would have.

[Alexei.Polkhanov]

Looks like it was some kind of stone. I have been in Sidney, AU and I noticed that there are many rocks and sand around that have this reddish color, exactly same color as shattered pieces embedded in a glass. I would expect meteorite fragments to be darker, but quick search for "red meteorite" immediately proves me wrong 

[orolo]

The contrast in the image could be fooling me, but it seemed that the tiny bump was off-center of the larger bump. Couldn't you infer the angle of impact from that? The tiny bump should be aligned with the trajectory of the impactor. The larger bump should have propagated almost perpendicularly to the panel (blunt trauma) -- the shattering circles on the tempered cristal look quite circular, not elliptical. So if the impact was perfectly normal to the panel, the tiny bump should be in the very center of the large bump. If the impact was very tangential to the panel, it should be quite off-center. From that and the position of the panel, perhaps the angle of impact could be guessed. Just an idea.

[probez]

Maybe applied science http://benkrasnow.blogspot.dk could come with his suggestions. I have followed his YouTube channel, and he definitely have the mind and tools. If he don't know he will research real deep. Try to see his own electro microscope or the old one he is modified to do digital animations.

[edy]

It was most definitely not a "micrometeorite". Any meteorite small enough to not punch a hole through your house would be traveling at terminal velocity of around 300kph by the time it gets to the ground. The impact crater you have in your panel could indicate an iron-nickel meteorite of something around 50 grams or more traveling at terminal velocity. It could also indicate the same size part or debris falling from a plane. Meteorites can have sharp points as well as can blue ice.

The debris you found in your microscope investigation is most likely a mix of random air particulates that fell over time, and in rain drops, along with many micrometeorites. You can collect 1 or 2 micrometeorites per every couple of days just by leaving a sheet of A4 paper outside and collecting the dust that accumulates. The reason you see these particles  in the shattered glass is because they were trapped there by the topology.

Sorry, not a micrometeorite, but still could be a 50+ gram or so stony meteorite or iron-nickel meteorite. Something that small (2-3 cm) could escape detection easily enough. Being so close to an airport makes the likelihood much higher of it being debris from a plane.

I tend to agree with this assessment...  A micro-meteorite just doesn't seem to have the necessary momentum to cause this kind of damage. The mass of the object times the velocity (which would be severely reduced by the atmospheric drag) would just not hit with enough force. If you were in outer-space, I could see this as being plausible as there would be no friction from air and it could travel at very high velocities.

Now if it was a LARGER meteorite, I would buy it. A larger meteorite would presumably hit the atmosphere at a high velocity, the friction would heat it up tremendously until a good portion of it burned it up... At some point it would slow down to the point of terminal velocity and perhaps also have time to cool a bit, before dropping like a stone straight down onto the roof.

Was there nothing on the lawn or the gutter that could be found when the object supposedly bounced off the roof?

I do agree that the object that hit the solar panel was small and sharp. Otherwise what could explain that very small bump on the opposite side (in the white material). It had to hit with enough force to permanently deform the plastic backing into a tiny bump.

[pickle9000]

Be interesting to use the microscope on an angle to get an idea of how far the particles are embedded, can they be knocked out?

Maybe put it on twitter https://twitter.com/neiltyson?ref_src=twsrc^google|twcamp^serp|twgr^author 

Hit it with a Geiger counter.

Any evidence of the glass melting?

[calexanian]

Looks very much like a golfball. I have a hard time reconciling either the small mass of a micrometeorite vs terminal velocity or the mass of a larger one vs the lack of puncture. The size of the coronal ring in that impact suggests something the size of a baseball. Unlikely in OZ. central pierce points like that are common in impacts of round blunt objects. I suggest a object of more mass moving at a lower velocity. Perhaps with a launch vehicle of perhaps 5 to 15 years of age.