The story of this book begins with the question "How did life originate and why were left-handed molecules selected for its architecture?" It is widely known that in processes triggering the origin of life on Earth, the equal occurrence, the parity between left-handed amino acids and their right-handed mirror images, is violated. The balance is inevitably tipped to the left - provoking that life's proteins today exclusively implement the left form of amino acids.

Why to the left?

If we rerun the tape of life's origin, would we once more obtain today's life using the left form of amino acids? Can't we think of mirror image life made of right-amino acids? Did mirror image life exist on Earth or does it exist somewhere else? What would mirror image life look like and how would it interact with the environment and with us? Puzzling questions of this kind contributed to the awakening of public interest in symmetry, the hypothetical existence of mirror image life, and its properties. Symmetry phenomena like these made also me curious and I began to separate molecules from their mirror image forms.

After several attempts, we were lucky to be engaged in the construction of the "Chirality-Module" of the ambitious cometary mission ROSETTA, an instrument designed to land on a comet and search for molecules and their mirror image forms. The idea is to trace the origin of life's left-handedness back to outer space.

Indeed, when we produced a comet analogue in the laboratory, we found a wide variety of amino acid molecules and their mirror image forms therein. The results supported not only the concept of the extraterrestrial delivery of prebiotic molecules triggering the appearance of life on Earth, now well-known and highly cited, but it provided a source of motivation in devoting an entire book to all the fascinating phenomena related to the asymmetry of life and its origin.

It is probably true that most scientists are solving more applied problems in biology, chemistry, physics, and mathematics. But we should always be alert to the great problems, such as understanding the processes leading to the origin of the one-handedness of life. Given past experience, such great questions will be solved - not by chance but by the prepared mind (Penny 2006). This book aims to be a starting point for the preparation of that mind by becoming a valuable resource for courses in chemistry, biology, biochemistry, and physics.

As Professor in Physical and Bioanalytical Chemistry, I was fortunate to work with and learn from Wolfram H.-P. Thiemann at the University of Bremen. He introduced me to the intriguing field of chirality, to theories on the origin of biomolecular asymmetry, and to the ROSETTA-COSAC community.

The international collaboration in my research field on the origin of life's molecular asymmetry was originally initiated by Helmut Rosenbauer at the Max Planck Institute for Solar System Research in Katlenburg-Lindau, Germany, via the ambitious conception and preparation of the COSAC-experiment onboard the ROSETTA Lander. My thanks go to Helmut Rosenbauer for this scientific support and his colleagues Fred Goesmann, Martin Hilchenbach, and Reinhard Roll for their fascinating basic work on COSAC and for plenty of conferences in the midst of fruitful discussions.

It was also a great pleasure to carry out scientific research within the international COSAC-team including Jan Hendrik Bredehoft, Jean-Francis Brun, Antonio Casares, David Coscia, Pascale Ehrenfreund, Guy Israel, Laurent Janin, Elmar K. Jessberger, Takekiyo Matsuo (!), Guillermo M. Munoz Caro, Francois Raulin, Robert Sternberg, Cyril Szopa, Hermann Wollnik, and Sandrine Zubrzycki, who provided their full cooperation and scientific support. I also appreciate related discussions with Franz R. Krueger, Kensei Kobayashi, and Jun-ichi Takahashi.

I acknowledge Alexandra J. MacDermott, University of Cambridge, UK and Clear Lake University in Houston, Texas, for innovative ideas and suggestions with respect to the detection of an enantiomeric excess in samples of non-terrestrial origin. I am glad for a number of instructive discussions on the origin of biomolecular asymmetry with Dilip Kondepudi, Wake Forest University, North Carolina, for valuable comments of Thomas Buhse, Morelos State University in Cuernavaca, Mexico, on chiral symmetry breaking, and for the very helpful and enlightening discussions on the theoretical complexity of magneto-chiral effects with Laurence Barron, University of Glasgow, and Geert Rikken, Grenoble High Magnetic Field Laboratory. Many thanks go to Wilfried A. König (|), University of Hamburg. John R. Cronin and Sandra Pizzarello, both of Arizona State University, and Volker Schurig, University of Tübingen, are acknowledged for helpful suggestions and discussions.

Intensive experimental collaborations were performed with J. Mayo Green-berg (!) at the Raymond and Beverly Sackler Laboratory for Astrophysics at the Leiden Observatory and his group composed of Guillermo M. Munoz Caro, Willem A. Schutte, and Almudena Arcones Segovia. I particularly acknowledge the pleasant cooperation with Greenberg's Ph.D. student Guillermo M. Munoz Caro, now at the Astrobiology Center in Madrid, and his carefully performed experiments on the simulation of interstellar ices with isotopically labelled reactants.

I particularly acknowledge the generous support from the Centre de Biophysique Moleculaire in Orleans. In October 2000, I became a member of the prominent laboratory of Andre Brack and Bernard Barbier and I would like to thank them as well as the whole CBM-team, including Ms. Marylene Bertrand-Urbaniak, Francois Boil-lot, Corinne Bure, Annie Chabin, Romain Jacquet, Mai-Julie Nguyen, and Frances

Westall for generous support in the laboratory and in language instruction. I explicitly thank Paul Vigny, former director of CBM, and Maryse Fauquembergue for the marvellous and complete organization of my French studies.

Advanced experiments with circularly polarized light were performed at the Synchrotron Centers LURE and SOLEIL in Paris at beamlines SA-61, SU-5 and DESIRS. I would like to acknowledge the staff of these research centers and especially the substantial and advanced studies of Laurent Nahon, Christian Alcaraz, and Bertrand Pilette on both the generation and detection of circularly polarized synchrotron radiation. Thanks also go to Louis d'Hendecourt and Michel Nuevo from the Institut d'Astrophysique Spatiale in Paris-Orsay and to Martin Schwell from the Universite Paris VII Denis Diderot. I also appreciate to work with S0ren V. Hoffmann at beamlines UV-1 and CD-1 at Arhus University, Denmark, in the Center of Storage Ring Facilities.

Thanks also go to Ray Wolstencroft, Royal Observatory at the University of Edinburgh, Scotland, for discussions and suggestions for the detection of circularly polarized light reflected from the planet Mercury by means of the BepiColombo mission of the European Space Agency (ESA).

I wish to thank Max P. Bernstein for his contributions and Jason P. Dworkin (both at NASA Ames Research Center, Moffet Field, California) for discussions on enan-tioselective chromatographic techniques for samples of interstellar ice analogues.

Moreover, I acknowledge lively discussions on the multifaceted chirality-phenomena with all members of my research team at the University of Nice-Sophia Antipolis namely Nicolas Baldovini, Katharina Breme, Cecilia Castel, Celine De-lasalle, Jean-Jacques Filippi, and Rodolphe Perriot.

The author thanks the Deutsche Forschungsgemeinschaft (DFG), Bonn, and the Agence Nationale de la Recherche (ANR), Paris.

And I would like to thank the well-disposed reader not only for following the ideas and concepts exposed in this book, but also for feedback, frank criticism, and suggestions.

Nice, Cap d'Ail, France, June 2008

Uwe Meierhenrich

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