nai

Project Progress

Cosmochemistry of Carbonaceous Meteorites (dm)

In this project we seek to understand the origin of pre-biotic organic molecules in carbonaceous chondrite meteorites and the origin and distribution of water (and other volatiles) on Mars.

In the past year we have had the unexpected pleasure of being able to study in detail a new, exciting meteorite fall, the Tagish Lake carbonaceous chondrite. We have examined the organic and inorganic inventory of this new, very primitive meteorite, leading to two published extended abstracts.

In the past year, we published a cover article in Geophysical Research Letters on the origin and evolution of water on Mars, based on an analysis of hydrous minerals in martian meteorite QUE 94201. In this work, we found the minerals to contain a mixture of water from two different sources, as delineated by their D/H ratios. First, the minerals contain primary “magmatic” water from the martian interior, with a D/H value ~twice terrestrial. This water was partially equilibrated with martian “meteoric” water, with a D/H value ~5 times terrestrial, as previously measured in the martian atmosphere. The big discovery here was the D/H value of magmatic water, which is much higher than previously assumed. This result has implications for the history of water on Mars, which probably involved a two-stage evolution, where early hydrodynamic escape was followed by Jeans escape of the atmosphere, a process that continues to the present day. In addition, the data imply that there may be ~2-3 times more water in the martian crust today than previously thought, which bodes well for martian biological potential.