Brussels, 12 Sep 2003
An international group of astronomers has confirmed the presence of complex organic molecules in the chemical composition of two comets, lending weight to the theory that comets played a major role in the creation of life on earth.
The research was carried out by scientists from Finland, France and the Netherlands, under the coordination of a team from the University of Liège in Belgium.
Early in the lifetime of our solar system, the newly created planets were bombarded by comets with nuclei composed of ice and dust. For decades, many scientists have suggested that the water and other organic molecules necessary for the emergence of life on earth may have originated from such impacts. Furthermore, it was felt that those comets that escaped such collisions and survived to the present day would provide a clear picture of the prevailing physio-chemical conditions some 4.6 billion years ago.
The team's first breakthrough came in 1997, when the Hale-Bopp comet passed within 194 million kilometres of earth. They analysed the object's chemical composition using observations from the Nordic optical telescope situated in the Canaries, and were surprised to detect levels of a heavy nitrogen isotope too high to have originated from simple molecules.
This discovery pointed to the presence of complex organic material in the comet, but to be certain of their conclusion, the astronomers needed to confirm the theory with further observations. They had to wait until the autumn of 2002 before a comet brilliant enough to allow precise measurements reappeared in the skies.
Using one of the instruments in the very large telescope (VLT) array in Chile, the researchers were able to confirm the presence of complex organic molecules on the WM1 LINEAR comet.
The group's work is expected to open new horizons in the study of comets. More fundamentally, where once these celestial objects were rumoured to bring defeat in battle and catastrophe to Earth, it could transpire that they carried with them something entirely less calamitous: life itself.