The quiet voice of interstellar glycine

Posted on March 12, 2010 by Invader Xan

So I’ve been sitting in on an online NASA astrobiology conference, The Organic Continuum from the ISM to the Early Solar System. Unfortunately I’ve missed most of it already, having only heard it was happening this evening when I was about to leave the office for the weekend. I hope they were recording it, as I’d love to catch the talks I didn’t manage to attend. I say attend. It’s nice to be able to “attend” a conference from your own living room. I love the internet.

Actually, I’m particularly disappointed that I managed to miss Allamandola and Ehrenfreund, but c’est la vie. I did manage to catch a talk on the Stardust mission and comet Wild2. It’s now well known that they found glycine streaming off the comet in its tail. In fact I’ve mused on comets and their role in astrobiology before. But I don’t work with comets. I’m an interstellar person. The places where I look for molecules are the spaces between the stars. Apparently, I may have my work cut out for me. Apparently, the quantities of glycine detected in Wild2 were so low that it’s scarcely any surprise that the molecule has so far eluded astronomical detection. Simply put, it’s below the threshold level for detection in astronomical spectroscopy. This, I must confess, comes as no surprise. So seemingly, there are only two possible ways to look for molecules like glycine in interstellar space. Serendipitously discover someplace with an exceptional overabundance of glycine, or take spectra with much much higher signal-to-noise ratios.*

One other thing which stuck in my mind is the ratios of two molecules — methylamine and ethylamine. Apparently those ratios match the ratios expected for methane and ethane. Methane and ethane are simple hydrocarbons. You probably learned about them in high school. To make methane into methylamine, you essentially need to chop off a hydrogen atom and stick on a nitrogen (well, it’s a little more complicated than that, but not by much). The same is true for it’s heavier brother** ethylamine. To me, the fact that the ratios match suggests that these things are forming in the comet itself. Be it by internal heating or by surface photochemistry, comets really are tiny icy orbiting chemistry labs.

I should really try and keep an ear to the ground for these internet conferences. Next time there’s one going on, I’d really like to be able to catch more of it!

*As is fairly self-explanatory, a signal-to-noise ratio is how much signal there is compared to how much background noise it needs to stand out from. It’s a bit like trying to hold a conversation in a crowded room. If there’s too much noise, you’ll only be able to hear the people who speak louder. You’ll have trouble hearing anyone who speaks too quietly. Interesting molecules like glycine, so it seems, speak very quietly indeed.

**For anyone who’s a fan of The Hollies, the joke should be obvious there…

Sharing is nice: About Invader Xan

Molecular astrophysicist, usually found writing frenziedly, staring at the sky, or drinking mojitos.
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