forum.sab-astro.fr

And ROSINA, a Rosetta instrument that uses spectrometers to measure gas abun-dances, has obtained a highly sought after result: the so-called deuterium-to-hydrogen ratio of water in the comet’s thin atmo-sphere, or coma. The measured value for 67P is much higher than the ratio in Earth’s oceans and higher than in other comets, says ROSINA principal investigator Kathrin Altwegg, of the University of Bern. Three years ago, the comet Hartley-2 was found to have a D-to-H ratio near that of Earth’s oceans—sparking interest in the notion that comet impacts delivered much of Earth’s water. Altwegg says the result for 67P could make asteroids the primary suspect again.