Yesterday I participated in the Smithsonian Institution’s Tweetup, a gathering of about 30 people interested in museums and science, but who also use Twitter. (I’ve also attended Tweetups organized by NASA.) I won’t give you a complete blow-by-blow description of the day, but if you want a feel for everything we did, please check out Jennifer Dorroh’s Twitter summary of the event.

We got a tour of the Museum Support Center, one of the Smithsonian’s storage and research sites, something very few non-researchers get to see. The main bits of the tour:

• Part of the “wet collection”: fish specimens preserved in alcohol, including a coelacanth! (Coelacanths are fish species related to the ancestors of all terrestrial vertebrates, including humans.) Our guide was Carole Baldwin, whose enthusiasm and depth of knowledge are incredible. She’s a well-known marine biologist who studies deep sea reefs and the species that inhabit them, so it was truly an honor that she took the time to meet a group of random people like us.
• We also got to see a wide selection of land snail specimens. Snails are a very diverse group, partly because they are slow moving: simple barriers of landscape can isolate populations, leaving evolution free to work its magic. About 30,000 species of land snails are known, with a diversity of shell structures or (in the case of slugs) no external shell at all. Many of those shells are very beautiful, and seeing them laid out was quite aesthetically, as well as intellectually, pleasing.
• The next stop was part of the anthropology area, where we saw shrunken heads from the upper Amazon peoples (collected as war trophies) and a few skeletons from people who donated their bodies to science. We also were able to see a collection of skulls exhibiting trephination, the practice (in this case by the aboriginal peoples of the Andes) of cutting a hole in the head to relieve pressure on the brain after an injury. We also saw the Soap Man, a man whose grave became waterlogged, leading to a bizarre transformation of his body fat into a soap-like substance. (This is why I love being a science geek among science geeks.)

The final bit of the tour was my favorite: a visit to the clean room housing the Smithsonian’s Antarctic meteorite collection. I had to try very hard to keep from going into Teacher Mode (which in turn is hard to distinguish from my Excited Fanboy Mode), where I start talking excitedly about the subject at hand to whoever is standing near me. Since it was a clean room, we all had to don smocks, hair nets, and booties; if we had been allowed to look at an actual meteorite from the collection, we would have needed to wear masks and gloves as well. The meteorites themselves were in sealed containers filled with a pure nitrogen atmosphere, a minimally reactive environment to keep the meteorites as uncontaminated as possible. To get one out to study, you would need to reach into the box using the gloves shown in the image above, transfer the meteorite to a small airlock on the side, and (making sure to handle it as little as possible) take it to a workshop bench within the clean room for examination.

Many meteorites are remnants of the debris left over from the formation of the Solar System, when small chunks of rock collided and aggregated into larger bodies like Earth. Not every scrap of available rock was used up in this process, and occasionally one (called a meteoroid while it’s traveling willy nilly through the Solar System) will cross paths with Earth and fall to the ground. Other meteorites are from Mars, blasted from the surface by another impact, and almost certainly chunks of rock on Mars originated on Earth too. (Caleb Scharf has more on that story.)

So, when studying meteorites, it’s important to keep them as pristine as possible: contamination by anything in the atmosphere or any organisms such as bacteria can change them, making it difficult to determine exactly what it is made of. If the meteorite is  from the early Solar System, then it tells us a lot about the chemical history and early conditions that led to what we see today. In fact, studying radioactive substances in meteorites like these provide a good double-check on the age of the Earth and Sun; the fact that their ages are around 4.5 billion years shows that we have a very good handle on how old Earth really is. Similarly, if the meteorite is Martian in origin, then it provides a window into another planet, including its chemistry and possible traces of life forms (though every story hyping the discovery of life in Martian meteorites so far has been more sound than substance). The Smithsonian meteorites are collected from Antarctica, since that’s already a fairly pristine environment: not much precipitation, and little chance of biological contamination.

I’m not a planetary scientist, but I’d love to go back in a kind of apprentice mode to study some of those samples. I’ve held meteorites (collected in less pristine conditions, so contaminated enough already that my dirty paws won’t hurt them much more), but there’s an additional intellectual thrill associated with touching something from Mars, or an object that has changed little in 4.5 billion years.

So, if my friends at the Smithsonian are reading this: thank you for a wonderful day, a wonderful tour, and I hope to be able to come back again.