Spectra of meteors

I forgot the charger for the laptop, so I had to try to think things out instead of looking them up.

What would meteors made of chunks of stuff like Bennu seems to be do when they hit the atmosphere? The soft conglomeration stuff should shatter easily and vaporize quickly, while the denser rock should punch through deeper. If the soft and hard stuff are made of different minerals, you should see different spectra at different points along the trail.

I tried to come up with a design to collect lots of data quickly, by having the telescope direction follow the radiant point, using a "cone" of mirrors inside to reflect concentric circles of light onto collector mirrors (of truly weird shape) and then onto diffraction gratings for on-line analysis. You'd get fairly coarse track resolution, of course. The whole business could be triggered by sensing whether there was a flash of light or not. (Too long a flash is an airplane or firefly, too short is an artifact or a coincidence. No flash means no meteor--just background.)

It could work. I think. There might be too much smearing of the image, though.

It turns out that this sort of analysis has already been done. If you shine the light on a diffraction grating, instead of getting a line in the sky you get a wide spectral smear, sort of like a feather--if you are lucky and the meteor's track is parallel to your grating. All it needs is lots of pictures and lots of patience and careful study of photographs of the steaks.

And different meteor showers do have different compositions. And there can be a difference in what appears at higher altitudes, as shown in the last image on that page.

Of course the atmosphere glows too when it gets hot, and there's black body radiation as well as the spectral lines, so it isn't trivial to parse out the details.