Bad Astronomy : Meteorite Mayhem III: solved?

According to a National Geographic news article, the meteorite that struck Peru recently (see here and here) really was a meteorite (and not a missile or anything else), and the reason people got sick in nearby villages is that it struck a location that had arsenic in the groundwater.

Yikes.

The impact site in Peru, filled with arsenic tainted water. Miguel Carrasco/La Razon/Reuters

We may finally have a story that makes sense. Samples of debris indicated it was extraterrestrial, but I wasn’t sure how much weight to give that. The crater looks odd, but it turns out to have hit near Lake Titicaca, and the soil composition and shallow water table may account for the shape. The crater is pretty substantial: note the people on the upper right of the rim in that picture for scale.

The claim now is that the meteoroid was hot when it hit (or the impact itself generated the heat), creating a steam plume tainted with arsenic — everyone who complained of illness has recovered, the report says, by the way. Given that we know it’s a meteorite now, that sounds plausible. Given the size of the crater and the eyewitness accounts, the meteoroid may have been big enough to retain quite a bit of heat when it hit. If it were, say (I am completely guessing here, but with reasonable numbers) a meter or so across and moving at 500 kph, the explosive energy at impact would be the same as 40 pounds of TNT, which actually sounds like it’s in the right ballpark to me. Impact energy is very sensitive to velocity, so if it were moving much faster the yield would be much larger.

Evidently pieces of shrapnel have been found, but I haven’t seen a picture of one! I’d love to; in general such pieces are very interesting and can be lovely.

So I guess it wasn’t a Scud missile, or a downed satellite, or an underground eruption, or or or. What we have here is potentially a lot more exciting. It will also make someone pretty wealthy, I imagine: meteorites are expensive, and ones with known falls and, better, an exciting story behind them, can fetch top dollar.