Search for life from the nm to the light year scale

Alexandre Simionovici, ISTerre, Université Grenoble Alpes | 7 juin 2018

– Pas de vidéo disponible pour ce séminaire.

Using the non-destructive, penetrative and high-resolution properties of the ESRF X-ray beams we have developed a highly sensitive hyperspectral methodology of analysis of solid materials to identify present or past traces of life. The new methodology combines X-ray fluorescence, tomography and speciation – and a brush-up of these techniques will be presented. We have designed and patented a quarantine extraterrestrial sample holder, aimed at analyzing samples from Returned Missions, such as JAXA Hayabusa 2, and NASA Osiris Rex and Mars 2025. The container was tested with a micrometer X-ray beam on several meteorites containing putative traces of life, and on bio-mineral analogs. Graduating from the current micron size to the future 10-20 nm size of X-ray beams enforces a “measurement revolution”, such as a re-evaluation of the sample preparation by advanced FIB techniques for sectioning and polishing extraterrestrial samples and the standards needed for quantitative calibrations. Progress towards this goal was achieved by analyzing samples in situ down to several tens of nanometers, and quantifying intermediate Z (atomic number) elements in low Z mineral and biological matrices down to a few ppm. This is the level at which life appears on minerals and to identify it, we plan to search for 20 nm to few µm closed-contour morphologies, encased in selectively permeable kerogenuous membranes, protecting them from the medium and controlling their fluid exchanges. Speciation of fingerprint intermediate Z key elements, so called “metallome”, camouflaged in low Z matrices, will indicate the nature of local exchange chemistry, pinpointing the location of specific minuscule chemical actors and finally revealing… LIFE.