Can we say anything definitive about organic materials in the early Solar System? Perhaps so, judging from recent news from the Carnegie Institution. Researchers there have found organic particles from the days of Solar System formation inside meteorites. The material is similar to what is found in interplanetary dust particles believed to have come from comets, and gives us a view of the complexity of the organic mix that may have been available as the planets formed.

Studying six carbonaceous chondrite meteorites, the researchers looked at different isotopes of hydrogen and nitrogen associated with insoluble organic materials, which are extremely difficult to break down chemically. The relative proportion of these isotopes can reveal much about how the carbon was formed, and the meteorite samples show in some cases even higher amounts of the relevant isotopes than those found in interstellar dust.

“We have known for some time, for instance, that interplanetary dust particles (IDP), collected from high-flying airplanes in the upper atmosphere, contain huge excesses of these isotopes, probably indicating vestiges of organic material that formed in the interstellar medium,” says Larry Nittler, a co-author on the paper that was published in the May 5 issue of Science. “The IDPs have other characteristics indicating that they originated on bodies — perhaps comets — that have undergone less severe processing than the asteroids from which meteorites originate.”

Meteorite mediumBut interplanetary dust particles provide only tiny samples; the new work makes it possible to examine much larger amounts of these materials from meteorites. What stands out to Centauri Dreams is a comment by another co-author, Conel Alexander: “…the parent bodies – the comets and asteroids — of these seemingly different types of extraterrestrial material are more similar in origin than previously believed.” And the study of early system organics just received a powerful boost.

Image (click to enlarge): These tiny particles, from carbonaceous chondrite meteorites, are just a few millionths of a meter wide and have different proportions of nitrogen (N) and hydrogen (H and D) isotopes. These isotopes are chemically bonded to meteoritic organic matter and can reveal a lot about what happened to the meteorite as it made its way through the solar system over billions of years. The two images show the regions with high levels of 15N and heavy hydrogen (deuterium or D)—indications that the associated carbon is very old and originated from interstellar matter or the outer regions of the solar system. Credit: Henner Busemann.

The paper is Busemann, Young, Alexander et al., “Interstellar Chemistry Recorded in Organic Matter from Primitive Meteorites,” Science (5 May 2006), pp. 727-730. Abstract available here.