Now, what's that gunk on my car? Clearly most victims of traffic accidents aren't human, they arent't even vertebrates. They are bugs, insects, tiny citters. They get smashed with a force a million times their weight and most don't leave much of a trace on headlights, radiators or windscreens.
But some do and they become, well, that gunk on your car. Why not give them a closer look? Or a real close one with an electron microscope?
To get these critters into the vaccum chamber of the microscope, they need to be removed from the car in some sort of way. It's not very practical to cut up your fender just to examine the bugs stuck to it. It's also not possible to scrape them off without destroying their fragile carcasses. So, the easiest thing to do is to cover the car in plastic foil to which the unfortunate collaterals of road traffic attach. Subsequently one only has to cut out the bugs and insert them into the microscope.
The procedure is a bit more complex than this, since specimens for a scanning electron microscope need to be electrically conductive. Bugs usually aren't, so these were covered in gold. It's just an extremely thin layer applied by a sputter coater in another vacuum chamber. Now it's time for microscopy, or, if you like, a bug post mortem.
Stuningly, most bugs seem quite complete after their encounter with a car, mostly the get hit at their heaviest part, the abdomen. This brakes and attaches to the vehicle. Legs, wings, antennae remain mostly intact. A good entomologist is still able to determine pretty savely what species the unfortunate insect belonged to. Why this sounds trivial and unimportant, it can play a role in police investigations. After all many insects live in very specific ecosystems and if you find them on a car, it's very likely that the car passed by an area that is home to the bug. A crime suspect who claims never to have been near the coast might like to change his testimonial if investigators find insects typical for the littoral on his car. Bad luck, this time not just for the squashed arthropods!
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