Blue Collar Scientist

Yesterday I gave the debut of my talk on exoplanets at the Campbell Creek Science Center, to a packed house, despite a lot of items competing for attention on the Anchorage social calendar that evening. Luise certainly knows how to do the publicity for these events. The CCSC is a consistently great venue; everything always works, the publicity is always done professionally and they almost always pack the house, and as a result of my eight appearances there I have a complete set of CCSC commemorative coffee cups to show off to my friends. (And I do use them!)

Anyway, while talking about exoplanets, I presented some evidence that showed that space is “filthy” with amino acids, sugars, and the elements necessary for life as we know it - i.e., carbon-based life, not necessarily life that looks like what we see on Earth. Unbeknownst to me, two pertinent studies on these topics were published the day of my talk - I didn’t hear about them until afterwards, because I hadn’t had a chance to go online anytime on Thursday.

Anyway, the two results bear directly on what I was speaking about. The first reports that the Spitzer Space Telescope has found more life-forming stuff in a protoplanetary disk:

Researchers using NASA’s Spitzer Space Telescope have discovered large amounts of simple organic gases and water vapor in a possible planet-forming region around an infant star, along with evidence that these molecules were created there. They’ve also found water in the same zone around two other young stars.

This isn’t exactly Earth-shattering news. We’ve found all these chemicals in protoplanetary disks and in star-forming regions before. The big advance here is twofold - first, they’ve pushed Spitzer to new levels of performance, squeezing the maximum amount of information from its observations. And second - they’ve found more of these pre-biotic chemicals¹ in protoplanetary disks than in the nebula they came from. In other words, the chemistry of life is formed in protoplanetary disks.

That’s pretty important, and very cool, and I’m really upset that I didn’t know about this in time to work it into last night’s talk. But I’ll be giving the talk again in a week at the Eagle River Nature Center, so I’ll be able to work this in there.

The second result bears on amino acids in meteorites. In my talk, I discussed the fact that amino acids had been found in meteorites, and that this was another indication that the universe was “filthy” with the building blocks of life.

The organic soup that spawned life on Earth may have gotten generous helpings from outer space, according to a new study. Scientists at the Carnegie Institution have discovered concentrations of amino acids in two meteorites that are more than ten times higher than levels previously measured in other similar meteorites.

In other words, there’s a lot more pre-biotic chemistry in our solar system than scientists had at first thought. Again, that’s pretty important, because part of my talk is all about how all this chemistry must be happening on billions, nay, even zillions, of roughly Earth-sized, terrestrial planets, all over the universe.

I speculate in the talk that the probability that life exists outside our solar system is 1. This is just more data to pile onto the evidence so far that the Earth is not unique.

1. Technically, what they’ve found is a greater proportion. [↩]

From Jen over at Skepchick, I learn of a news story reporting the discovery of an amino acid precursor in a distant galaxy, Arp 220. The stories (so far) are published at National Geographic and Discovery, and you can find the original press release here. Although Discovery published last month, I hadn’t noticed it amongst the flood of other news from the AAS conference in Austin last month.

Amino acids were found in space in 1994, when glycine was found in Sagittarius B2¹. Glycine is a very simple amino acid, and serves as an inhibiting neurotransmitter in vertebrates, including humans. Sagittarius B2 is a molecular cloud in the Milky Way - a cold region rich in dust and complex molecules that give birth to stars.

Amino acids or their precursors have since been found in a number of molecular clouds, as well as in meteorites. At least five different amino acids have been reported in the Murchuson meteorite, and in 1994 it was discovered that the meteorite had an excess of left-handed amino acid. Polarized ultraviolet light - which has been found in nebulae such as M42, the big bright nebula in the sword of Orion - can preferentially destroy amino acids of one particular handedness over another. The relative mystery of why all life on Earth utilizes left-handed amino acids might therefore have a celestial explanation. If the first amino acids utilized by life came from space, it is likely there was an excess of left-handed molecules as a result of polarized light from the star forming region that gave birth to the sun and the solar system.

The discovery in Arp 220 is of methanimine, which can form the amino acid glycine when it reacts with hydrogen cyanide and then water, or with formic acid. What’s neat about the discovery is that formaldehyde, ammonia, hydrogen cyanide, and probably formic acid have already been discovered in the galaxy’s primary star-forming region. This is, in other words, a snapshot of some of the raw materials for life, being formed in space.

Over 130 molecules have now been found in space - including sugar. We’re to the point that finding amino acid precursors in space isn’t really all that newsworthy. But to the best of my knowledge, this is the first time that such precursors have been found in a distant galaxy, and the first time they have been found in an active galaxy. That’s pretty cool - it establishes that our local galactic neighborhood isn’t really all that special when it comes to the formation of complex molecules in space.

1. the original discovery was called into serious question, but further, more rigorous study, did confirm glycine in space. [↩]