Plenary session review

Posted by Julian Heath

This comprised talks by Tom Pike from Imperial College London on 'The Phoenix Mission: Microscopy on Mars' and Joe Michael and PG Kotula of Sandia National Labs, New Mexico, on 'Microbial Forensics: Microanalysis of the 2001 Anthrax Letter Attacks' separated by the MSA and IMS Awards presentations.

Tom Pike gave us a spectacular overview with stunning images and dramatic video sequences of the development, operation and results from the first atomic force microscope to land on Mars. The Phoenix Lander was launched in August 2007 and analyzed samples of Martian dust collected by the robotic shovel on the Lander. Tom explained how his team faced the design challenges of the AFM specification: 100 grams, no piezo scanner, multiple disposable cantilevers and stabilized samples. The result was an electromagnetic scanning microscope that had a nanobucket substrate to trap the nanometer-sized particles in the Martian red dust. Analysis of the particles without any chemical data was even more challenging but a sophisticated fractal dimension analysis of the range of particle sizes showed no clays - confirming the absence or long-since departed presence of water - but the presence of kaolinite and denticulated pyroxene and smectite.

Joe Michael delivered a detailed account of his role in the analysis of the anthrax powder terrorism incident in October 2001: 22 people were infected from contaminated letters and five died. Joe's team at Sandia was asked to analyze the matrix surrounding the bacterial spores and but found little. SEM imaging and EDX analysis combined with ADF STEM,  TOF-SIMS and FIB were used in a correlated analysis of the anthrax spores. The data showed that letters delivered to Leahy, the New York Post and to Senator Daschle were very similar and the controversy arising from an earlier discrepancy in the matrix composition of the anthrax-dosed letters could be simply explained by the fact that the perpetrator recultured some bacterial samples; so the conspiracy theory/idea that there was more than one terrorist is probably untenable.