nai

Project Progress

Theme 4 is concerned with the development of measurement protocols and techniques that will inform the development of instruments for organic analysis on space missions to comets. Comet missions have been planned and proposed to NASA and other space agencies for a nucleus rendezvous for a period of weeks or months or for a nucleus flyby through more than one coma to explore cometary diversity. The Rosetta spacecraft developed by the member states of the European Space Agency will encounter Comet Churyumov-Gerasimenko in May 2014. For both flyby or rendezvous mission types, sample return concepts have been developed and the first such return will be in January 2006 with the Stardust samples of Wild 2 contained in the aerogel collectors on that spacecraft. Since return of cometary ices in a preserved state may not be possible in the near term from multiple comets, in situ measurements must be used to explore the cometary molecules that may have contributed directly (or not) to the origin of life on Earth.

There is a significant overlap in the development of instrumentation and measurement protocols for in situ chemical and isotopic analysis in a cometary nucleus and those that might be used to carry out a sensitive search for organic molecules on Mars. During the reporting period Dr. Arnaud Buch returned to a university position in Paris and plans were made for his replacement with another highly qualified astrobiologist Dr. Oliver Botta whose future work will be a combination of studies of organics in suitable analogues for comets and Mars and analysis of meteoritic and other terrestrial samples using GC-MS. Dr. Botta has several different types of meteorites that will be analyzed for their amino acid composition. In addition, he will study the organic composition of Antarctic meteorites with respect to contamination from the ice.

In related work Daniel Glavin has initiated a program to investigate the distribution and isotopic composition of nucleobases in carbonaceous meteorites that was also supported in 2004 by the Exobiology program. This research is a collaborative effort between NASA Goddard (Jason Dworkin and Oliver Botta), Carnegie Institution of Washingon (Marilyn Fogel) and the Leiden Institute of Chemistry in The Netherlands (Zita Martins). Dr. Glavin presented a summary of the first year research at the 2005 PI Exobiology symposium at NASA Ames. He also proposed to analyze amino acids in STARDUST comet grains using a highly sensitive liquid chromatography time of flight mass spectrometry and laser induced fluorescence detection technique. This work is a collaborative effort between NASA Goddard (Jason Dworkin) and the University of Washington (Graciela Matrajt).

Not funded by the NAI, but very relevant to our work are results from a detailed cometary coma MHD model developed by a GSFC National Research Associate Dr. Mehdi Benna. The model provides more detailed resolution of the structures due to the solar wind interactions than has previously been developed and can model either a very active comet or solar wind interactions down to the nucleus for a weak comet far from the sun. This work will be important for interpretation of data from spacecraft missions to comets as the space environment where the organic measurements are being made will be better understood. Future development of the model will add more chemical complexity and predictions of the structure and chemistry of trace species.