ROSINA detects argon at Comet 67P/C-G

The noble gas argon has been detected in the coma of Comet 67P/Churyumov-Gerasimenko for the first time, thanks to the ROSINA mass spectrometer on-board Rosetta. Its detection is helping scientists to understand the processes at work during the comet’s formation, and adds to the debate about the role of comets in delivering various ‘ingredients’ to Earth. The new results are reported in Science Advances today and describe data collected on 19, 20, 22, and 23 October 2014, when the comet was around 465 million km (3.1 AU) from the Sun, and Rosetta was in a 10 km orbit around the comet. During the time spent close to the comet, the ROSINA instrument was able to take an inventory of the key constituents of the comet’s coma, with many ingredients already reported (see links at end of article). Determining the chemical make-up of comets is a necessary step to understanding their role in bringing water and other ingredients to the inner planets during the Solar System’s early history. The so-called noble gases (helium, neon, argon, krypton, xenon, and radon) rarely react chemically with other elements to form molecules, mostly remaining in a stable atomic state, representative of the environment around a young star in which planets, comets, and asteroids are born. In addition, their abundance and isotopic compositions can be compared to the values known for Earth and Mars, and for the solar wind and meteorites, for example. The relative abundance of noble gases in the atmospheres of terrestrial planets is largely controlled by the early evolution of the planets, including outgassing via geological processes, atmospheric loss, and/or delivery by asteroid or cometary bombardment. Thus the study of noble gases in comets can also provide information on these processes. However, noble gases are very easily lost from comets through sublimation, and […]

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