EEVblog #846 - Solar Panel Micrometeorite Impact! - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: January 28, 2016, 09:47:26 am
content: Dave uses a microscope to examine the shattered LG Mono-X solar panel. Was it a micrometeorite impact?And what are the odds of a micrometeorite impact on a typical solar power installation in a given year?

author: danielschroeder
author_rank: Newbie
timestamp: January 28, 2016, 10:21:52 am
content: I think it was a stone thrown by a lawn mover

author: Fungus
author_rank: Super Contributor
timestamp: January 28, 2016, 10:22:16 am
content: Get a big magnet and see if the pieces stick to it (iron).

author: Muttley Snickers
author_rank: Unknown
timestamp: January 28, 2016, 10:25:37 am
content: Whack four legs on it and flog it on Ebay as a one in a million coffee table, some dude might be after a conversation piece, you never know.On a side note an old wise fellow once told me that everything we have and will ever have comes from below, nothing at all from above, sunlight being the exception, think about it.

author: EEVblog
author_rank: Unknown
timestamp: January 28, 2016, 10:38:43 am
content: Quote from: danielschroeder on January 28, 2016, 10:21:52 amThe angles would make it almost impossible to get enough impact.

author: lapm
author_rank: Frequent Contributor
timestamp: January 28, 2016, 10:48:06 am
content: Im mostly impressed that panel still works after hit like that.. Wondering if it took out only that one cell...

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 28, 2016, 10:52:14 am
content: I wonder if a small meteorite would still have enough momentum after travelling through the atmosphere. As size reduces the surface-area to weight ratio, and hence drag ,increases, reducing terminal velocity.It should be possible to calculate based on maximum typical meteorite speeds what the terminal velocity would be at a range of sizes.I also wonder if this could simply be a manufacturing flaw, maybe on the inside surface, combined with thermal cycling causing the pre-stressed toughened glass to fail, the pattern being simply the progression of the failure from the flaw.IMO the next stage would be to carefully pick away the glass & retreive as many particles as possible, & get someone to look at them under a proper microscope - once removed from the panel, size and transport are no longer problems.The indent on the back is interesting, and maybe more supportive of an impact than a flaw - I'd certainly be interested to see some careful excavation from that side.Maybe you could use an angle grinder or diamond wheel to cut out the section to make it more portable for further analysis.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 28, 2016, 10:54:14 am
content: Quote from: EEVblog on January 28, 2016, 10:38:43 amNot to mention the energy that would be lost getting it up to sufficient height.

author: wraper
author_rank: Unknown
timestamp: January 28, 2016, 10:57:11 am
content: The impact actually does not need to be that big. It's the the object is what needs to be very hard, you can shatter the tempered glass with a relatively small impact. Look how tempered glass can be easily shattered with a piece of porcelain from a broken sparkplug. Watch from the 4th minute.

author: Brumby
author_rank: Unknown
timestamp: January 28, 2016, 11:02:59 am
content: My first suggestion of a cricket ball was based on a rather macro view. Considering the microscopic examination, that idea is hereby withdrawn.As for the micrometeorite size - it must be pointed out that the 270x10-9g mass cited is anaverage. Dave could easily have had an encounter with one that was much larger than this.Maybe - but, the probability is not zero (as I heard someone say recently).

author: Fungus
author_rank: Super Contributor
timestamp: January 28, 2016, 11:07:55 am
content: Wonder what a meteorite like that would do if it hit you on the head...

author: Brumby
author_rank: Unknown
timestamp: January 28, 2016, 11:08:45 am
content: 800% more damage.

author: Fungus
author_rank: Super Contributor
timestamp: January 28, 2016, 11:11:39 am
content: Quote from: Brumby on January 28, 2016, 11:08:45 amJoke all you want. I'm buying a helmet.

author: EEVblog
author_rank: Unknown
timestamp: January 28, 2016, 11:14:36 am
content: Quote from: wraper on January 28, 2016, 10:57:11 amIt does if it has to get through the glass and the panel to make an indent and ripple impact pattern on the back.

author: HAL-42b
author_rank: Frequent Contributor
timestamp: January 28, 2016, 11:14:54 am
content: Called it in the last threadAlthough a micrometeorite that tiny would be falling only at terminal velocity. So 2mm or 5mm stone wouldn't do any damage. We are probably looking at something done by 20mm to 50mm object at free fall.It must have bounced after the impact and is probably laying somewhere nearby.

author: EEVblog
author_rank: Unknown
timestamp: January 28, 2016, 11:17:52 am
content: Quote from: Brumby on January 28, 2016, 11:02:59 amOf course it must have been much larger, or panels and other things would be getting shattered all over the globe, and people getting injured etc.Whatever it was, it is a rare event.Again, LG Australia haven't seen or heard about this level of impact shattering in 300,000 of these panels installed. Even after the worst hail storms.

author: Brumby
author_rank: Unknown
timestamp: January 28, 2016, 11:20:38 am
content: It would be really interesting to find out what those embedded flecks are...Anyone with a mass spectrometer?

author: EEVblog
author_rank: Unknown
timestamp: January 28, 2016, 11:25:57 am
content: Quote from: Brumby on January 28, 2016, 11:20:38 amI'm after one (or similar) for another thing I want analysed. Been unable to find access to one so far.

author: Rerouter
author_rank: Super Contributor
timestamp: January 28, 2016, 11:28:55 am
content: It to me implies a wood screw or rivet head. as an object that would have the shape and mass to cause a similar fracture pattern, The circles of shattering would be the peaks of the impact displacement ripple, making an initial displacement, then the distance between shears in the glass decreasing due to loss of energy thanks to loss of intensity as it spreads away,There is some math screaming out in the back of my head about how to calculate the delivered energy, but i'll retire that for the night, but it would be along the lines of energy to shatter the glass from a 0.5mm surface, plus the energy to displace the plastic lining past its elastic phase, assume for non radioactive elements, and leaves a good idea of the mass,

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 28, 2016, 11:29:39 am
content: Quote from: Fungus on January 28, 2016, 11:07:55 amProbably not much - to break tempered glass it's all about surface pressure - the internal pre-stress will do the rest. So if the initial contact area is small and very hard, it probably wouldn't take a huge amount of momentum. if you were hit by something of similar size, you'd possibly feel it, and it may make a small cut but I doubt it would cause significant injury as skin is a lot less hard than glass, so the energy would be quickly absorbed.Of course it could inject you with an alien parastite...

author: dr.diesel
author_rank: Super Contributor
timestamp: January 28, 2016, 11:32:55 am
content: Quote from: mikeselectricstuff on January 28, 2016, 11:29:39 amAh, that explains a good portion of the people here in the states.

author: wraper
author_rank: Unknown
timestamp: January 28, 2016, 11:34:26 am
content: Quote from: EEVblog on January 28, 2016, 11:14:36 amIf that is what it looked like in eevblog #844, it looks more like the material which is covering the back side of the panel just delaminated because of the moisture which got into the panel.I think it could be some small object (like 0.5-1.5 cm in size) and a very hard (like porcelain, tungsten carbide, or diamond) with a very sharp edge. The issue with micrometeorite theory is that they loose their speed while reaching the earth, therefore cannot produce a significant impact.

author: bktemp
author_rank: Super Contributor
timestamp: January 28, 2016, 11:41:17 am
content: Quote from: Fungus on January 28, 2016, 10:22:16 am+1 for the magnet. The colour looks right, it could be oxidized iron. If it sticks to the magnet you can be alomst 100% sure it is no rock thrown there but something that has fallen from the sky (either from space or from a plane).

author: HAL-42b
author_rank: Frequent Contributor
timestamp: January 28, 2016, 11:48:47 am
content: Quote from: bktemp on January 28, 2016, 11:41:17 amThere must be a way to test without dislodging or magnetizing the specimen. RF maybe?

author: Halcyon
author_rank: Unknown
timestamp: January 28, 2016, 11:56:50 am
content: Quote from: bktemp on January 28, 2016, 11:41:17 amProbably just dirt and dust that's blown over since the break. Very common to see red dust especially if you live anywhere near a new suburb or development in Sydney. I'm still trying to get rid of dirt that my servers and switches have sucked up at my old place.

author: TheAmmoniacal
author_rank: Unknown
timestamp: January 28, 2016, 11:57:39 am
content: Is the back panel a steel plate?

author: Muttley Snickers
author_rank: Unknown
timestamp: January 28, 2016, 12:02:08 pm
content: 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.

author: Brumby
author_rank: Unknown
timestamp: January 28, 2016, 12:21:26 pm
content: No.But I am now ....

author: Muttley Snickers
author_rank: Unknown
timestamp: January 28, 2016, 12:30:17 pm
content: Quote from: wilfred on January 28, 2016, 12:20:35 pmBugger.....I just read the plot and was hoping for an early night, I will put the kettle on.....

author: HAL-42b
author_rank: Frequent Contributor
timestamp: January 28, 2016, 01:09:41 pm
content: Seems like our layman classification of 'micrometeorite' is wrong. Look at the plainMeteoritepage on Wikipedia.MeteoriteImpact on a roof shingle (different impactor, not the one above)

author: necessaryevil
author_rank: Regular Contributor
timestamp: January 28, 2016, 01:55:08 pm
content: 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...

author: Fungus
author_rank: Super Contributor
timestamp: January 28, 2016, 02:15:20 pm
content: Quote from: Muttley Snickers on January 28, 2016, 12:02:08 pmBall bearings don't shatter.

author: Tek_TDS220
author_rank: Regular Contributor
timestamp: January 28, 2016, 02:25:00 pm
content: 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?

author: cdev
author_rank: Super Contributor
timestamp: January 28, 2016, 03:05:43 pm
content: 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.

author: Fungus
author_rank: Super Contributor
timestamp: January 28, 2016, 03:27:57 pm
content: Quote from: Tek_TDS220 on January 28, 2016, 02:25:00 pmOr ... 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)

author: dr.diesel
author_rank: Super Contributor
timestamp: January 28, 2016, 03:42:30 pm
content: 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.

author: mikerj
author_rank: Super Contributor
timestamp: January 28, 2016, 03:48:07 pm
content: Quote from: cdev on January 28, 2016, 03:05:43 pmThe fracture pattern and the big dent in the back of the panel are pretty much conclusive of an impact rather than temperature induced stress.

author: G7PSK
author_rank: Super Contributor
timestamp: January 28, 2016, 04:40:51 pm
content: 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.

author: cdev
author_rank: Super Contributor
timestamp: January 28, 2016, 05:08:15 pm
content: 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, includingACARS, 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 freeACARSDECsoftware 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=ACARShttps://www.google.com/search?q=ACARS+RTL2832Try 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

author: Lightages
author_rank: Unknown
timestamp: January 28, 2016, 05:17:31 pm
content: 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.

author: Rog520
author_rank: Regular Contributor
timestamp: January 28, 2016, 05:25:14 pm
content: 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!

author: Stonent
author_rank: Super Contributor
timestamp: January 28, 2016, 05:32:28 pm
content: You could potentially collect the particles with a coffee filter over a vacuum cleaner hose.

author: Stonent
author_rank: Super Contributor
timestamp: January 28, 2016, 05:34:18 pm
content: If only LG had made their panels out of Solar Freakin' Roadways. They can hold a tractor.

author: Nerull
author_rank: Frequent Contributor
timestamp: January 28, 2016, 06:28:51 pm
content: 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.

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: January 28, 2016, 06:37:38 pm
content: 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

author: orolo
author_rank: Frequent Contributor
timestamp: January 28, 2016, 07:07:41 pm
content: 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.

author: probez
author_rank: Newbie
timestamp: January 28, 2016, 07:41:05 pm
content: Maybe applied sciencehttp://benkrasnow.blogspot.dkcould 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.

author: edy
author_rank: Super Contributor
timestamp: January 28, 2016, 07:43:45 pm
content: Quote from: Lightages on January 28, 2016, 05:17:31 pmI 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.

author: pickle9000
author_rank: Super Contributor
timestamp: January 28, 2016, 07:44:29 pm
content: 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 twitterhttps://twitter.com/neiltyson?ref_src=twsrc^google|twcamp^serp|twgr^authorHit it with a Geiger counter.Any evidence of the glass melting?

author: calexanian
author_rank: Super Contributor
timestamp: January 28, 2016, 08:16:18 pm
content: 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.

author: Fungus
author_rank: Super Contributor
timestamp: January 28, 2016, 08:58:38 pm
content: Quote from: calexanian on January 28, 2016, 08:16:18 pm"Coronal ring"?That's just the way glass breaks.eg.https://encrypted.google.com/search?q=bullet+hole+in+glass&tbm=isch

author: ozwolf
author_rank: Regular Contributor
timestamp: January 28, 2016, 09:26:07 pm
content: Lot's of interesting ideas and theories, however, usually the answer will be the simplest scenario.I think most likely a cricket ball (about the right size), followed closely by stone from lawn mower (hmm, big impact area for that), and then remotely a ball bearing from slingshot (too small I think). I should probably also suggest a golf ball.Try Googling "cricket ball damage" and "golf ball damage". I believe one of these is the most likely scenario.Ozwolf

author: ozwolf
author_rank: Regular Contributor
timestamp: January 28, 2016, 10:30:02 pm
content: Quote from: G7PSK on January 28, 2016, 04:40:51 pmI was thinking more about this as I drove to work this morning. I like the scenario of a cricket ball/golf ball impacting and bouncing over the ridge. Dave, have you considered speaking to your neighbours to see if they have picked up any random items in their yards? I would start with the neighbour "over the ridge" side of your home.Ozwolf

author: calexanian
author_rank: Super Contributor
timestamp: January 28, 2016, 10:50:15 pm
content: Quote from: Fungus on January 28, 2016, 08:58:38 pmTough crowd. Try to use a high voltage reference and they jump all over you.

author: pickle9000
author_rank: Super Contributor
timestamp: January 28, 2016, 10:59:07 pm
content: Throw a ball at another panel. Maybe LG has one you could use, good excuse to make a cricket cannon.

author: Barny
author_rank: Frequent Contributor
timestamp: January 28, 2016, 11:03:12 pm
content: Hey, you have all forgotten the marks at the back site.The object which hit the panel had enough energy to smash the hardened glass, the solar cell itself ans leaves a small, sharp pointed dent in the back site.If it was something like a cricket ball or golf ball, the dent wouldn't look like this.The object was small (<5mm / < 0.2inch) and was impacting with high speed.Possible objects:small meteorite -> improbable but not impossiblea gun bullet -> in Australia even more improbable then a small meteoritecrossbow bolt -> the bolt wout probably bounced of but its not impossibleplane part -> the part would not be fast enough to make this type of damage...In the end, no one knews the type of object.(Except the part gets discovered.)

author: EEVblog
author_rank: Unknown
timestamp: January 28, 2016, 11:14:21 pm
content: Quote from: Barny on January 28, 2016, 11:03:12 pmCorrect.Everyone keeps harping on about kids with rocks, slingshots etc. It's definitely not that.Someone now says they have spoken to several experts in meteorites and they both say it's very likely a meteorite, golf ball size or even a bit larger, hit on some pointy edge.QuoteI'm not ruling out something from a planeCrossbow bolt is even more implausible than a bullet.

author: HAL-42b
author_rank: Frequent Contributor
timestamp: January 28, 2016, 11:44:08 pm
content: Dave, it is most likely in the rain gutter or somewhere nearby. You must put us out of this misery.

author: mtdoc
author_rank: Super Contributor
timestamp: January 29, 2016, 12:08:32 am
content: Has anyone mentioned vandalism? How easy is it to get up on your roof? Even if improbable, it's got to be at least as plausible as a meteorite.

author: Stonent
author_rank: Super Contributor
timestamp: January 29, 2016, 01:21:01 am
content: I blame Giorgio Tsoukalos.

author: Brumby
author_rank: Unknown
timestamp: January 29, 2016, 01:55:37 am
content: Quote from: EEVblog on January 28, 2016, 11:14:21 pmThat's where my thinking is heading as well. Terminal velocity considerations mean there would have to be a larger mass involved than that of a micrometeorite. The penetration and dimple out the back suggests to me that the impact velocity was significant - and that tends to make the idea of a terrestrially launched object somewhat improbable.The other thing that, to me at least, excludes the possibility of a cricket ball (unless it had a sharp piece of something like blue metal (gravel) embedded into it) is the actual damage to the glass itself. By looking closely at the centre, we see an area less than 1mm across where the glass is all white. To me, this is where the glass has been crushed - by direct and intensepressurefrom the initial point of contact of the object. All other fracturing radiates out with increasing size of the glass pieces, indicating less intense forces (if any) and the fundamental radial fracture pattern of tempered glass.The final thing which gives me more confidence in the meteorite idea is that, if you don't know what to look for, the offending object will just be another rock in the back yard.

author: TheCharels
author_rank: Contributor
timestamp: January 29, 2016, 03:22:40 am
content: How about Australian ninjas?Dave have you checked for ninjas recently?

author: Razor512
author_rank: Regular Contributor
timestamp: January 29, 2016, 03:34:32 am
content: It has to be a pigeon's high velocity poop attack. They like to poop on cars, and anything else shiny. The issue is that they have noticed that people don't often look at their solar panels, thus they have to work harder on the way they deliver the poop to the surface of those panels.Pigeons have found that it is effective to accelerate to high speeds, and then poop on the panels.

author: rrinker
author_rank: Super Contributor
timestamp: January 29, 2016, 03:38:04 am
content: Pigeons in America just leave unsightly droppings, usually on your freshly washed and waxed car. But those Australian pigeons - like the Australian version of most animals, they are 100x as deadly......

author: miguelvp
author_rank: Super Contributor
timestamp: January 29, 2016, 03:48:18 am
content: There is no reason to believe that if it was a ball it would have left residue.The outer broken rings are consistent with a ball. The inner point is just due to the concentrated pressure transferred through the glass of the point of impact, the reason it looks that small is because it was broken by the upper glass layers, nothing to do with the object other that the object being round has a small point of impact.The even more outer cracked rings increment at almost equidistant rates half the diameter of the impact.Not a micrometeorite but a baseball or something like that.

author: EEVblog
author_rank: Unknown
timestamp: January 29, 2016, 03:57:57 am
content: This mob reckon it's not a meteorite:http://fireballsinthesky.com.au/2016/01/has-this-solar-panel-been-hit-by-a-meteorite/Although they do only say micrometeorite which I agree with.

author: miguelvp
author_rank: Super Contributor
timestamp: January 29, 2016, 04:08:08 am
content: Quote from: EEVblog on January 29, 2016, 03:57:57 amHmm, to me it seems they say it's not a micrometeorite.Gretchen says that if it was really that small it would have been slowed down a lot before impacting the solar panel if it was indeed a micrometeorite.Martin says Cricket ball, also mentioning the outer rings as not being consistent with a micrometeorite.Edit, or even a meteorite because of the explosive nature it wouldn't have those big outer rings.

author: EEVblog
author_rank: Unknown
timestamp: January 29, 2016, 04:21:18 am
content: Quote from: miguelvp on January 29, 2016, 04:08:08 amCricket ball size round object surely does not explain the small crushed impact point as Brumby pointed out. It just doesn't fit.Seem I now have competing meteorite experts, two saying it likely is, and two saying it likely isn't.

author: miguelvp
author_rank: Super Contributor
timestamp: January 29, 2016, 04:22:37 am
content: Space debris impacts:4mm impact in solar cell retrieved from space:Source:http://www.esa.int/spaceinimages/Images/2003/12/Impact_crater_size_4_mm_on_solar_cell_retrieved_from_spaceHubble solar panel impacts:Source:https://www.quora.com/What-is-the-likelihood-of-something-like-space-debris-damaging-satellites-or-astronauts-like-shown-in-the-movie-Gravity-What-safeguards-does-NASA-provide

author: pickle9000
author_rank: Super Contributor
timestamp: January 29, 2016, 04:24:56 am
content: From my perspective the investigation is the fun part.

author: miguelvp
author_rank: Super Contributor
timestamp: January 29, 2016, 04:25:47 am
content: Quote from: EEVblog on January 29, 2016, 04:21:18 amOn impact the upper glass will break off pushing to the lower layers concentrating the impact shard into a point on that lower layer, but the damage is done by the glass pushing down so it looks like a small point but that's the point of maximum pressure on the impact.

author: ejeffrey
author_rank: Super Contributor
timestamp: January 29, 2016, 04:31:15 am
content: Quote from: miguelvp on January 29, 2016, 03:48:18 amI actually doubt that a baseball or cricket ball would even break the glass. It is too slow, too soft, and too blunt. We aren't talking about a MLB player hitting a ball directly into the panel at short range, we are talking about a fly ball from some kids playing in their back yard or whatever. Those glass panels are tough. It would need to be something denser, harder, and faster. Unless kids is australia use diamond studded cricket balls, I don't think that is it.A chunk of metal from a plane (or maybe ice) seem more likely to me than a meteor, but honestly I have no idea what the even rate of either would be. Either would at least explain the observations as far as I see.

author: Brumby
author_rank: Unknown
timestamp: January 29, 2016, 04:36:45 am
content: Quote from: miguelvp on January 29, 2016, 04:22:37 amNo atmosphere to slow down or burn up anything - so even the smallest meteoroids will still have significant velocity.

author: miguelvp
author_rank: Super Contributor
timestamp: January 29, 2016, 04:53:54 am
content: This is my hypothesis:The glass pieces on the higher energy part of the impact causes the small pinpoint damage on the lower layer, as the ball gets deeper there is more surface to slow the ball down in a logarithmic fashion, then you get the traversal wave damage across the rest of the panel.

author: EEVblog
author_rank: Unknown
timestamp: January 29, 2016, 05:01:37 am
content: Quote from: Brumby on January 29, 2016, 04:36:45 am11km/s apparently. Not pretty.

author: Razor512
author_rank: Regular Contributor
timestamp: January 29, 2016, 05:05:45 am
content: Has anyone ever tried catching oncoming space debris with their hand while outside of the space station?

author: boffin
author_rank: Unknown
timestamp: January 29, 2016, 05:16:55 am
content: I'm going to throw out a completely different idea; I believe it was a nut (acorn/walnut/hazelnut) dropped by a bird 10-30m above.The colour of the debris reddish/brownTrees nearby

author: miguelvp
author_rank: Super Contributor
timestamp: January 29, 2016, 05:20:09 am
content: Quote from: miguelvp on January 29, 2016, 04:53:54 amLet's also not forget we are talking about tempered glass not your everyday glass, so when it breaks it will transfer the energy to the lower layers in a more concentrated manner.

author: calexanian
author_rank: Super Contributor
timestamp: January 29, 2016, 05:32:41 am
content: Quote from: miguelvp on January 29, 2016, 04:53:54 amagreed. that kind of pinpoint is similar to what happens when a large rock hits a windshield. I have had it happen to me a few times while driving down the highway.

author: cdev
author_rank: Super Contributor
timestamp: January 29, 2016, 05:35:12 am
content: A recent space probe used aerogel to catch comet dust. Space debris moves a little too fast for the usual methods of catching things.Quote from: Razor512 on January 29, 2016, 05:05:45 am

author: miguelvp
author_rank: Super Contributor
timestamp: January 29, 2016, 05:54:11 am
content: Quote from: calexanian on January 29, 2016, 05:32:41 amMaybe it was a rock, since a cricket ball or baseball might be too soft as others mentioned, maybe a golf ball but I seriously doubt it was a micro meteoroid

author: Lightages
author_rank: Unknown
timestamp: January 29, 2016, 06:00:59 am
content: Please, speeds of impact in outer space are completely different that impact speeds on the surface of the Earth. Outside of the Earth's atmosphere speeds can exceed 100 kilometers per SECOND. Impact speeds at the surface of the Earth for common impacts range from almost zero to maybe 300 kilometers per HOUR. This is orders of magnitudes lower in energy. A 0.1 mm scale sized piece of debris in outer space at 20 kilometers per SECOND has huge amounts of kinetic energy and can kill a person. A golf ball sized piece of debris at 300 kilometers per HOUR might have the chance of killing a person if it hit them on the head. Please stop comparing meteor hits in orbit around the Earth with meteorites hitting the surface of the Earth. They are nowhere near comparable.Dave's panel was hit with something going less than 300kph, period. Based on the damage it could have been a nut falling from an airplane, a small meteorite, or maybe a chunk of blue ice. Any debris found in the crater is useless for analysis to determine what hit the panel after a couple of days as crap is falling from the sky in the form of dust sized particles continuously.Unless Dave finds a 2cm to golf ball sized meteorite, a nut or bolt, or feces in the yard, this will never be solved.

author: Muttley Snickers
author_rank: Unknown
timestamp: January 29, 2016, 06:02:53 am
content: I came across a video earlier of a golf ball sized ice block simulating large hail being fired at a solar panel at high velocity in slow motion, not even a scratch to the panel and the projectile completely disintegrated, what a waste of a good ice block.Also found some very interesting stuff on spudfiles.com, sorry I can't link either from this silly device.

author: calexanian
author_rank: Super Contributor
timestamp: January 29, 2016, 06:18:42 am
content: Quote from: Lightages on January 29, 2016, 06:00:59 amAgreed. Things like a AA battery from a sling shot and the like should also be considered. A D cell battery from a wrist rocket can do some hefty damage as a younger me could attest.

author: free_electron
author_rank: Super Contributor
timestamp: January 29, 2016, 06:20:14 am
content: It's an early prototype of a batteriser that blew up, went suborbital and landed.

author: miguelvp
author_rank: Super Contributor
timestamp: January 29, 2016, 06:27:56 am
content: Found a picture of a rock damaged solar panel, won't link it because of the political aspects of it.Pretty much a group of people threw rocks at this person's solar panels.As for hail damage, there are plenty of pictures on the internet about that, but this was a single impact so it was not hail, but it can damage panels too.Right now I'm inclined to a rock, not a small one.

author: pickle9000
author_rank: Super Contributor
timestamp: January 29, 2016, 06:29:57 am
content: Quote from: free_electron on January 29, 2016, 06:20:14 amSome sort of monkey explosion?

author: EEVblog
author_rank: Unknown
timestamp: January 29, 2016, 06:48:14 am
content: Quote from: Razor512 on January 29, 2016, 05:05:45 amNot possible I believe, because anything in same height orbit as the astronaut would be going at the same speed as the astronaut. It's not like stuff is just darting around all over the place out there, all things in the same orbit must have the same speed. And if something accelerate then you must change it's orbit.

author: EEVblog
author_rank: Unknown
timestamp: January 29, 2016, 06:50:19 am
content: Quote from: miguelvp on January 29, 2016, 06:27:56 amYes, you can (not easily) smash panels with rocks and other things, but how many of them produce sharp protrusions out the back and ripple wave impact patterns on the back surface?That requires a lot of force, something I greatly doubt you can get from something throwing something.

author: EEVblog
author_rank: Unknown
timestamp: January 29, 2016, 06:55:09 am
content: Quote from: Lightages on January 29, 2016, 06:00:59 amYes, but it's almost certainly faster than something someone could throw. I thin ka lot of energy is required to give the protrusion and wave pattern on the back. I have yet to see this on any other solar panel impact video or photo.QuoteI'm not so sure, because I only see it directly in the centre, and what looks to be embedded in the glass chards. I don't see anything further out, it's very clean.QuoteI suspect that's the case.

author: Lightages
author_rank: Unknown
timestamp: January 29, 2016, 06:58:35 am
content: Quote from: EEVblog on January 29, 2016, 06:48:14 amWRONG! Just because something is at the same level of an astronaut does not mean it is in orbit. I can be going a delta of anything from 0 kph to over 100s of kilometers per second. It could be a piece of rock passing by the Earth, or something in orbit around the Earth that was further than the moon at its furthest. Please, stop talking about space and astronomy if you don't know about it.FYI, I have been an amateur astronomer, and sometimes "professional", for over 45 years. I am not talking out of my ass.

author: mtdoc
author_rank: Super Contributor
timestamp: January 29, 2016, 07:00:07 am
content: Do kids have BB or pellet air guns in Australia ?

author: Muttley Snickers
author_rank: Unknown
timestamp: January 29, 2016, 07:05:01 am
content: Quote from: mtdoc on January 29, 2016, 07:00:07 amAbsolutely not, they are classed as a firearm, same applies to slingshots, etc

author: Lightages
author_rank: Unknown
timestamp: January 29, 2016, 07:06:15 am
content: A BB or pellet would not do this damage.

author: miguelvp
author_rank: Super Contributor
timestamp: January 29, 2016, 07:07:27 am
content: Quote from: EEVblog on January 29, 2016, 06:50:19 amWell I don't have pictures of the other side of the panel but it's consistent with the damage, the initial impact point will definitely travel to the other side causing that pinpoint protrusion because of how tempered glass breaks. The ripple wave damage is just harmonic damage when the peaks combine since the panel is not rigid.My guess is still that someone threw a large (about 10cm diameter or a bit smaller) rock to your panel, most likely a roundish rock as found by rivers.

author: Muttley Snickers
author_rank: Unknown
timestamp: January 29, 2016, 07:20:03 am
content: It was a message from above, the context and protocol are yet to be determined.....

author: EEVblog
author_rank: Unknown
timestamp: January 29, 2016, 07:20:48 am
content: Quote from: Lightages on January 29, 2016, 06:58:35 amYes, but we are talking about space junk in orbit around the earth. Always happy to be corrected, I'm not expert on it, that's why I said "I believe". Relax.But yes, you are right, now that I think of it same height orbits can have different directions of course, so hence different directions and hence relative speeds to each other.Orbital things mostly travel in the same orbital direction though do they not?And no, I will not stop talking about something I find interesting, even if I am wrong.The point I was trying to make is that (I believe, correct me if I am wrong), two objects at the same height orbit going in the same direction and path,mustbe travelling at the same speed, yes?Why don't you correct me on typical space junk then and answer the question. How likely is it that an astronaut can reach out and grab "space junk" (that has presumably been up there a long time, and essentially presumes the same orbit and direction?)?I say not likely because it'll either be going to ridiculously fast due to some different orbital directional, or it'll be in different orbit entirely. i.e. how likely is it that random space junk "just floats by" the space station?

author: Halcyon
author_rank: Unknown
timestamp: January 29, 2016, 07:21:43 am
content: Quote from: calexanian on January 29, 2016, 06:18:42 am800% more damage with the Batteriser!(Sorry, it was there, ripe for the picking.)

author: mtdoc
author_rank: Super Contributor
timestamp: January 29, 2016, 07:46:32 am
content: Quote from: Lightages on January 29, 2016, 07:06:15 amAt close range, I would think they could. I've seen first hand what they can do to a tempered glass door and to metal siding.But no matter if they're not present in Australia

author: ElectroNub
author_rank: Contributor
timestamp: January 29, 2016, 07:48:54 am
content: Have you searched the area with a metal detector?This is how meteor hunters find them!

author: EEVblog
author_rank: Unknown
timestamp: January 29, 2016, 08:06:38 am
content: Quote from: ElectroNub on January 29, 2016, 07:48:54 amI don't have one.

author: pickle9000
author_rank: Super Contributor
timestamp: January 29, 2016, 08:50:26 am
content: Quote from: Lightages on January 29, 2016, 07:06:15 amNot a normal one anyway, there are some very large caliber variants (try "pellet gun pig hunting" on youtube).In any case lead is long lasting and should be present in the case of an air rifle.The feature I like on the panel is the wave on the back just like a drop of water hitting a still pond. I can't ever remember seeing a projectile cause that kind of shape. Puckers and holes sure but the wave is pretty cool.

author: TheSteve
author_rank: Unknown
timestamp: January 29, 2016, 09:22:32 am
content: Quote from: EEVblog on January 29, 2016, 08:06:38 amTime for a metal detector build video...

author: ozwolf
author_rank: Regular Contributor
timestamp: January 29, 2016, 10:24:20 am
content: Quote from: mtdoc on January 29, 2016, 07:46:32 amBelieve me, BB guns and pellet rifles are all around, don't kid yourself.However, I don't think this pattern is from those impacts.Ozwolf

author: ozwolf
author_rank: Regular Contributor
timestamp: January 29, 2016, 10:27:26 am
content: Quote from: miguelvp on January 29, 2016, 04:53:54 amThis scenario gets my vote.Ozwolf

author: EEVblog
author_rank: Unknown
timestamp: January 29, 2016, 11:08:23 am
content: Quote from: ozwolf on January 29, 2016, 10:24:20 amThere are a grand total of 3 houses who have site access to my rooftop array, nothing visible from the road. They have to shoot from their top floor window, or be a random lob shot over the houses and down the gully. The odds round down to zero.There is a grand total of one house that has yard access that could potentially have kids with balls, lawn mower throwing a rock etc (of which I have never seen nor heard of kids playing ball or other games there). People love to come up with all sorts of simple theories like these, which is fine, but sorry, they do not cut the mustard. My array is quite physically isolated from such things.

author: Fungus
author_rank: Super Contributor
timestamp: January 29, 2016, 11:17:25 am
content: Quote from: ozwolf on January 29, 2016, 10:27:26 amIt's a1mm hole,right through to the back of the panel. There's NO WAY you could get that dent on the back with a larger object.This thread is starting to make my brain hurt. I don't think I can take any more.

author: Barny
author_rank: Frequent Contributor
timestamp: January 29, 2016, 12:36:09 pm
content: Let them believe what they want.There are enough people which think the world is a disc.Because there is no new stuff in the Butteriser section, people need to search new playground.And if there isn't one, they have to make one.Even if they have to stick to impossible theories.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 29, 2016, 12:36:32 pm
content: Quote from: Fungus on January 29, 2016, 11:17:25 amBear in mind that the glass turns to small fragments very rapidly - I think it's plausible that a large blunt object could cause rapid fragmentation on initial contact, and one of those fragments then gets pushed through the rear as the object continues moving.

author: RogerRowland
author_rank: Regular Contributor
timestamp: January 29, 2016, 12:55:10 pm
content: If the panel were still under tension in some place, maybe you could lob a cricket ball at it to try to recreate the same effect. Who knows? It might give useful info even so .....

author: Brumby
author_rank: Unknown
timestamp: January 29, 2016, 12:55:50 pm
content: I don't see glass 'fragments' at the centre of the impact area - I seepowderedglass.There might be a larger object involved - but the high pressure impact zone clearly indicates a hard, pointy object (~ 1mm diameter at the very tip) has made the initial, impulse contact.

author: rrinker
author_rank: Super Contributor
timestamp: January 29, 2016, 01:11:06 pm
content: OK, here's my crazy option - I stress crazy. Are there any raptors that hang around the area (the bird kind)? So suppose one was flying over, looking for a mouse or small rodent, whatever happens to live in the area - and maybe one was running across Dave's roof, or maybe the bird just saw its own reflection in the glass of the panel and thought it was an intruder - and dove on the panel. Bang, sharp beak, right into the panel. Bird is only stunned, not dead, so by the time anyone bothers to look, the bird has recovered and sheepishly flown away.Like I said - crazy, I don't really believe this - much.

author: Brumby
author_rank: Unknown
timestamp: January 29, 2016, 01:29:29 pm
content: We do have a couple of birds of prey around Sydney - but they're not exactly common.Also, they aren't known for dive-bombing solar panels.

author: Dinsdale
author_rank: Regular Contributor
timestamp: January 29, 2016, 01:44:06 pm
content: The best evidence is probably going to be in the depression in the back panel.It's possible that whatever caused that dent is still there.I'd try to get someone who has experience to examine your panel.Mythbusters can test the effects of various objects impacting your model of solar panel. Who you gonna call?

author: Brumby
author_rank: Unknown
timestamp: January 29, 2016, 01:47:38 pm
content: Funny that...I was wondering about throwing this one to the Mythbusters as well.

author: AndreasF
author_rank: Frequent Contributor
timestamp: January 29, 2016, 01:55:27 pm
content: Quote from: Brumby on January 29, 2016, 01:47:38 pmToo late for that. Final season finished filming some months ago.

author: Muttley Snickers
author_rank: Unknown
timestamp: January 29, 2016, 02:03:21 pm
content: Quote from: Brumby on January 29, 2016, 01:29:29 pmThis reminds me of a TV show whereby one of those khaki shorts wearing people was showing off a big hairy funnel web spider on an outside table to the presenter and a kookaburra swooped down out of nowhere, grabbed it and took off and the dude in shorts didn't have a spare, I forget how it ended but it was a good laugh.

author: Dinsdale
author_rank: Regular Contributor
timestamp: January 29, 2016, 02:08:48 pm
content: QuoteSh*t! Maybe they like to do it for Tested?

author: Yansi
author_rank: Super Contributor
timestamp: January 29, 2016, 03:23:43 pm
content: Quote from: TheSteve on January 29, 2016, 09:22:32 amLol, I've been thinking exactly the same!

author: Jacko
author_rank: Contributor
timestamp: January 29, 2016, 04:54:19 pm
content: For small meteorites, it seems that the atmospheric drag strips away the cosmic velocity while it is still several miles above the earth and you are left with the simple terminal velocity like any other object dropped from a height.A steel BB shot up into the air has a terminal velocity of 111.8 mi/hr (or 179.9 km.hr) when it falls back to earth. That could make a good dent in anything that it encounters. I'm guessing that a 4.5mm meteorite would have similar performance.

author: PeterL
author_rank: Regular Contributor
timestamp: January 29, 2016, 06:11:34 pm
content: The small pointy dent on the back doesn't seem to be in the centre of the two bigger circles if you know what I mean. So I wonder if the centre of the crater on the front lines up with this small dent, or with the big circles?

author: Lightages
author_rank: Unknown
timestamp: January 29, 2016, 07:00:25 pm
content: Quote from: EEVblog on January 29, 2016, 07:20:48 amYup I should relax. Sorry I posted such a grumpy response.

author: cdev
author_rank: Super Contributor
timestamp: January 29, 2016, 07:56:04 pm
content: My money would be on it having been caused by a chunk of so called"blue ice"falling from an airliner.Example:Why is human waste falling from India's skies?http://www.bbc.com/news/world-asia-india-35255102here are the first few paragraphs of the story."In India, as in many other countries around the world, it is considered good luck when a bird poos on you.But as an unfortunate Indian woman has discovered, there is nothing lucky about being hit by other kinds of falling excrement.The Times of India reports that Rajrani Gaud from Madhya Pradesh suffered a severe shoulder injury when she was hit by a football-sized chunk of ice last month.Her injuries could have been much worse, according to eyewitnesses. They say she only avoided being killed because the icy ball crashed into the roof of a house before hitting her.And the strong suspicion now is that this chilly projectile was composed of more than just frozen water.The newspaper claims that aviation scientists believe she may well have had the misfortune to become one of an incredibly rare group: people who have been hit by what the airline industry coyly calls"blue ice".That's its euphemism for the frozen human waste that very occasionally forms around the overflow outlets for aeroplane toilets, and then falls to earth. "Blue" because of the chemicals added to the toilets in planes to reduce odour and break down the waste.Blue ice falls are unusual, but not unheard of.Plane toilets store human waste in special tanks. These are normally disposed of by ground crews once the plane has landed, but international aviation authorities acknowledge that lavatory leaks can occur in the air."Truncated..Source:http://www.bbc.com/news/world-asia-india-35255102

author: Wytnucls
author_rank: Super Contributor
timestamp: January 29, 2016, 08:34:56 pm
content: Blue ice is a thing of the past. Modern airliners (Airbus and Boeing) have closed vacuum systems with clean flush water draining into waste tanks. Waste water from the basins and galley sinks is drained overboard through heated masts, helped by differential pressure at altitude.

author: EEVblog
author_rank: Unknown
timestamp: January 29, 2016, 08:57:23 pm
content: Quote from: Wytnucls on January 29, 2016, 08:34:56 pmThat's seems to be the consensus on that, so I think that can be ruled out.Someone mentioned actual ice forming on the plane by the time it gets to my place (30km out or so) it might have enough height for that

author: HAL-42b
author_rank: Frequent Contributor
timestamp: January 29, 2016, 09:07:35 pm
content: Quote from: EEVblog on January 29, 2016, 08:57:23 pmThat is possible but unlikely to do any damage.

author: JazzHarper
author_rank: Contributor
timestamp: January 29, 2016, 10:01:07 pm
content: It's estimated, based on meteorite finds in desert areas, that meteorites larger than 10g reach the surface of the earth at a rate of 1 per million km2per year. Dave's solar panel installation has an area of 1.93e10-5km2, so the probability of an impact on the array in any given year would be 1.93e10-11. That's 1 in 52 billion, if my math is correct. Meteorites smaller than 10g comprise the vast majority of mass that falls to earth, but have very little kinetic energy when they reach the surface; they are essentially dust.

author: Fungus
author_rank: Super Contributor
timestamp: January 29, 2016, 10:33:56 pm
content: Quote from: JazzHarper on January 29, 2016, 10:01:07 pmDave's a lucky guy!

author: jnissen
author_rank: Regular Contributor
timestamp: January 29, 2016, 10:50:23 pm
content: It has to be a rock or hard ball. I don't buy the micro-metorite or even a larger meteorite theory. Way to low of probability. Much more likely to have a rock thrown up from a lawn mower. I have panels in my back yard and I have to be very careful when mowing as I was warned by the installer that rocks from mowing are a common cause of panel damage. I use a lawn tractor with a 22 HP motor and three blade deck. When it gets hold of a rock it can toss it an amazing distance and terrific force. I know this as I have had to change the mower blades a time or two. The impact ring seems to show it may have even been a ball that may have been launched by a mower. I unfortunately find balls in the grass all too often as my dog will carry these things into the yard. Tennis balls get ripped to shreds but a baseball or hard ball turns into a dangerous projectile.Perhaps these guys live near you Dave?https://youtu.be/dRS5mBt6J-o

author: Brumby
author_rank: Unknown
timestamp: January 30, 2016, 01:10:27 am
content: Quote from: PeterL on January 29, 2016, 06:11:34 pmI noticed that as well - and I find your question an interesting one. I suspect the ding out the back will line up with the fine point of impact at the front, but I am interested in how the ripple impact pattern on the back lines up with the front face.Dave - if you have a moment, can you check that?I'm thinking the pointy bit of an object hits first, causing the crushed point of intrusion - but that this was a bit off centre with the bulk of the object's mass then impacting the glass with more of a blunt force trauma. The pointy bit causes the ding out the back and the bulk mass the ripple impact pattern.Object could be a rock with a pointy bit - or a cricket ball with a nail stuck in it.

author: Dinsdale
author_rank: Regular Contributor
timestamp: January 30, 2016, 01:35:13 am
content: I think you can draw a straight line between any two points.

author: SL4P
author_rank: Super Contributor
timestamp: January 30, 2016, 03:51:28 am
content: I'm still in - for a 12mm (1/2-inch) nut or such falling from a plane at 25,000 feet. It would hit and bounce maybe 10-20m at that speed/angle/distance.

author: Brumby
author_rank: Unknown
timestamp: January 30, 2016, 06:31:28 am
content: Don't forget - Sydney is a waypoint for air traffic passing through. It's not uncommon for flights from New Zealand to pass overhead at 30,000ft or more on their way to Asia, for example..

author: PeterL
author_rank: Regular Contributor
timestamp: January 30, 2016, 08:07:30 am
content: Quote from: EEVblog on January 29, 2016, 08:57:23 pmYou could check on flightradar24.com or similar sites at which height the big birds pass over your house.

author: Brumby
author_rank: Unknown
timestamp: January 30, 2016, 08:20:00 am
content: Quote from: PeterL on January 30, 2016, 08:07:30 amI have the App on my phone - and I often check when I hear something overhead. That's how I know about the NZ flights to Asia...

author: PeterL
author_rank: Regular Contributor
timestamp: January 30, 2016, 08:26:53 am
content: Quote from: Brumby on January 30, 2016, 01:10:27 amI have no idea about the construction of these pannels, but maybe the pointy bit is something between the layers, like a spacer or so. Knowing how everything lines up would certainly give a better insight in this matter.

author: SeanB
author_rank: Super Contributor
timestamp: January 30, 2016, 09:07:43 am
content: I would guess it is space debris, probably a deorbited Progress vehicle, or the remains of the launch vehicle upper stage as it deorbited and burned up on re-entry into the atmosphere on its way to final impact in the South Pacific Ocean. As it hits the upper atmosphere you get stress and compression heating, which ablates small parts off the vehicle as it descends on the final part of the orbit, taking small pieces of debris off along the way. Sydney is on the right path for the final orbit path to pass over, and the craft will be low enough at the time that it will be experiencing significant stress and heating.Orbital path of MIR, and you can see that the final landing site was close to Australia, while the ISS path does often pass over Sydney, especially in the summer months.http://www.satview.org/spacejunk.phpDepending on when the damage was done, it could even be this one.http://www.space.com/29344-falling-russian-spacecraft-reentry-tonight.htmlhttp://earthsky.org/space/doomed-russian-spacecraft-to-fall-from-space

author: FrankT
author_rank: Regular Contributor
timestamp: January 30, 2016, 10:13:13 am
content: Quote from: danielschroeder on January 28, 2016, 10:21:52 amI think it was a stone thrown by a Dxxkhead.

author: Fungus
author_rank: Super Contributor
timestamp: January 30, 2016, 12:09:46 pm
content: Quote from: jnissen on January 29, 2016, 10:50:23 pmWhat does probability have to do with it?Random shit happens all the time.Dave didn't plan for this to happen. He wasn't sat there waiting for it. If he'd made a video last year saying, "I've just put my panels up, now let's wait for the meteorites...",thenyou could start calculating probabilities.He didn't. Random shit happened. End of.

author: Svuppe
author_rank: Regular Contributor
timestamp: January 30, 2016, 03:57:58 pm
content: Probability or not, they do fall from time to time, and they have to land somewhere.Here is one I have. 3 cm long, 12 grams and with 18% iron.

author: Brumby
author_rank: Unknown
timestamp: January 30, 2016, 04:14:26 pm
content: Hey Dave!!Looks like we've found whodunnit....

author: Brumby
author_rank: Unknown
timestamp: January 30, 2016, 04:16:38 pm
content: But ... hmmmm ..... maybe not. 12g seems a bit light for the damage caused...But the shape looks right

author: Lightages
author_rank: Unknown
timestamp: January 30, 2016, 04:32:22 pm
content: Here is an example of what could have caused the damage. This is a iron nickel meteorite that I have that fell in Russia in 1947. It weighs 47g.

author: 6581
author_rank: Unknown
timestamp: January 30, 2016, 07:17:44 pm
content: This thread is rapidly turning into "show us how your meteorite looks like." Does everyone here have their own meteorites?

author: TeaNTronics
author_rank: Contributor
timestamp: January 30, 2016, 10:21:19 pm
content: i think it might be a good idea to put security camera on the roof facing the panels.for monitoring the panels

author: Tinkerer
author_rank: Frequent Contributor
timestamp: January 30, 2016, 11:57:02 pm
content: Quote from: Yansi on January 29, 2016, 03:23:43 pmAlso my thought. If it is an actual metorite that can be recovered, you are looking at something that could be worth some serious money. Collectors and the like will pay big dollars for these things. Especially in some cases if they have an interesting story.I would be willing to bet that if it was a meteorite, it was metallic in composition.

author: Don Hills
author_rank: Regular Contributor
timestamp: January 31, 2016, 12:05:27 am
content: Quote from: wilfred on January 30, 2016, 04:25:23 amThere was a Mythbusters episode (it's on Youtube) about "blue ice". Briefly, it forms at altitude and falls off on approach to landing.

author: VK3DRB
author_rank: Super Contributor
timestamp: January 31, 2016, 02:33:53 am
content: I am sceptical. Your, er, "micrometeorite" is more likely from a neighbour who chucked a yonnie on your roof. A piece of bluestone with a sharp corner could hit the solar panel and bounce off, leaving little or no residue. Given the right shape and impact, the force could be huge. The particles in on the broken glass could be just ingressed dirt from the rain. You might want to check around your house for the projectile.But I am not a complete sceptic. There is evidence there are aliens among us. The evidence is at US Immigration at airports, where there are two entry queues with signs above them, "US Citizens" and "Aliens".

author: G7PSK
author_rank: Super Contributor
timestamp: January 31, 2016, 10:34:13 am
content: I still think it was a cricket ball that after impact went over the ridge. The shape of the dent on the under side of the panel is caused by the glass deflection on impact, fingers of glass deflected downwards.

author: Fungus
author_rank: Super Contributor
timestamp: January 31, 2016, 01:39:18 pm
content: Quote from: G7PSK on January 31, 2016, 10:34:13 amDave: Get a cricket ball and throw it as hard as you can at that panel. Shut these people up once and for all.Even better: Find a good cricket player to throw it for you, or shoot it from a cannon.(Also a golf ball....)

author: pickle9000
author_rank: Super Contributor
timestamp: January 31, 2016, 11:23:17 pm
content: Can we vote? I wanna cannon.

author: Brumby
author_rank: Unknown
timestamp: February 01, 2016, 01:09:03 am
content: Quote from: Fungus on January 31, 2016, 01:39:18 pmJust limit the velocity to 300 km/h.

author: Fungus
author_rank: Super Contributor
timestamp: February 01, 2016, 01:28:21 am
content: Time to confess:It was actually me that broke the panel, trying to send a Fluke 27 into orbit (from Spain!)If it only made it to Australia I think I need to up the launch current a bit.

author: Stonent
author_rank: Super Contributor
timestamp: February 01, 2016, 07:05:58 am
content: Quote from: Muttley Snickers on January 29, 2016, 07:05:01 amCan't trust your citizens with many things...

author: G7PSK
author_rank: Super Contributor
timestamp: February 01, 2016, 10:02:04 am
content: They have guns in Australia just as they do any where else in the world including the UK which has some of the strictest in the world. I am in the UK and I have guns which are legally held. Spent round can go for miles and even in some cases be lethal. There was a case here in the 70's where a shot gun pellet went over a mile through an open window and hit someone in the eye and entered the brain, and it was not bear shot just plain old bird shot, so it is not impossible for that to be a stray bullet.https://en.wikipedia.org/wiki/Gun_laws_in_Australiahttps://en.wikipedia.org/wiki/Firearms_policy_in_the_United_KingdomDespite what this says you can still get hand guns for special purposes such as putting down wounded deer if you are a stalker and black powder guns are not banned at all.

author: Brumby
author_rank: Unknown
timestamp: February 01, 2016, 10:51:43 am
content: Yes, there are guns in Australia - but the culture here is anything BUT.The chances of meeting someone in the street who actually owns any sort of firearm is extremely, ridiculously low. If the average person were to encounter someone with a rifle, the conversation would not be about whether it was a Winchester or a Browning, whether it had a customized stock, what sort of ammunition they're using or checking out the scope. It would be something like "Nice gun".Urban Australia does not embrace the gun.

author: Nerull
author_rank: Frequent Contributor
timestamp: February 02, 2016, 12:51:33 am
content: I don't know why people keep saying "micrometeorite" - A little rock that would fit between the pins of a dip package did not do that. The worst it would do is irritate your foot if it fell in your shoe.

author: mtdoc
author_rank: Super Contributor
timestamp: February 02, 2016, 04:46:14 am
content: Quote from: Nerull on February 02, 2016, 12:51:33 amHa Ha !- exactly. And a meteorite big enough to do this damage is exceptionally improbable (but not impossible) - which is why another explanation is more likely IMO. I doubt we'll ever know for sure though.

author: ornea
author_rank: Unknown
timestamp: February 02, 2016, 09:05:04 am
content: Mantis Shrimp sucked up on a storm and rained down on the panel. Annoyed it unleashed the awesome power of the claw ...Has a target arrow fired skyward been considered.It doesnt have the debris that Dave identified and I dont think it could cause the deep depression seen but may cause the dimple shown on the back side of the panel.

author: coppice
author_rank: Super Contributor
timestamp: February 02, 2016, 09:09:40 am
content: Quote from: ornea on February 02, 2016, 09:05:04 amYummy!Despite what they say about mantis shrimp being able to punch through glass tanks, I have never see a restaurant use thick glass to contain them.

author: Fungus
author_rank: Super Contributor
timestamp: February 02, 2016, 10:07:07 am
content: Quote from: mtdoc on February 02, 2016, 04:46:14 amAs Tim Minchin likes to point out: People who say things are 'impossible' based on probability alone are seriously underestimating the number of things that happen every second.What's the chances that a one-in-a-trillion event just happened to hit Dave's house?Well... it's only one-in-a-trillion if you believe that Daveplannedit that way.If you assume Davedidn'tplan it then it's just one more 'random' event in a massive universe where 10^{SMALLINT} things happen every second.The test for 'meteorite' would be to check the iron/nickel content of the black bits in the hole.The test for "cricket ball" would be to propel a cricket ball at the other half of the panel and see if it resembles the impact (people would still argue about angles and velocities though, so...)

author: coppice
author_rank: Super Contributor
timestamp: February 02, 2016, 10:12:49 am
content: I wonder how many little repair jobs Australian roofers get each year, replacing one mysteriously broken roof tile?

author: nctnico
author_rank: Super Contributor
timestamp: February 02, 2016, 02:32:04 pm
content: Quote from: coppice on February 02, 2016, 10:12:49 amI had a broken roof tile once. Over here it is usually attributed to frost/heat damage but it could have been a meteorite as well. The ceramic/concrete tiles commonly used in the NL last for at least a century and breakage is extremely rare.

author: iXod
author_rank: Frequent Contributor
timestamp: March 02, 2016, 04:37:56 pm
content: Quote from: EEVblog on January 28, 2016, 11:25:57 amAsk Mike of MikesElectricStuff channel. I'm sure he probably has one in his garage...Or Applied Science channel's Ben Krasnow. He'd be up for the challenge for sure...