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The ROSINA observations also revealed a remarkable correlation of argon with molecular nitrogen, N 2, of 36Ar/N 2 = (9.1 ± 0.3) × 10 −3, while the ratio with respect to H 2O showed a much larger variation of 36Ar/H 2O = (0.1 to 2.3) × 10 −5. The 36Ar/ 38Ar ratio was measured to be 5.4 ± 1.4, and this ratio is in agreement with the solar abundance ratio of 5.37 ( 11) within (large) errors. In October 2014, at a 10-km distance from the nucleus, ROSINA detected 36Ar and 38Ar, the two stable primordial noble gas isotopes of argon, respectively ( 10). As the environment became increasingly dusty close to perihelion and the Rosetta star trackers encountered problems distinguishing stars from illuminated grains of cometary origin, the spacecraft was moved to larger cometocentric distances with lower dust abundances.Įarly in the mission, Rosetta spent an extended amount of time close to the nucleus.
![sw krypton sw krypton](https://i.pinimg.com/736x/88/44/5b/88445b5f1df5414cc3a5402508000347--exterior-paint-colors-color-paints.jpg)
As the comet approached the Sun, the activity increased and peaked some 2 to 3 weeks after perihelion passage ( 6). The major components in the coma have been shown to be H 2O, CO 2, CO, and O 2 ( 3, 4), with strong variations depending on the location of the spacecraft with respect to the comet’s heliocentric distance and solar illumination angle ( 5). The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) monitored the abundances of volatiles in the coma of the comet in situ at the location of the spacecraft ( 2). In August 2014, the comet moved from a heliocentric distance of more than 3 astronomical units (AU) to perihelion in August 2015 at 1.24 AU and again away from the Sun. The European Space Agency’s (ESA) Rosetta spacecraft accompanied comet 67P/Churyumov-Gerasimenko (hereafter 67P/C-G) over 2 years ( 1). Hansen, Ernest Kopp, Axel Korth, Diana Laufer, Léna Le Roy, Urs Mall, Bernard Marty, Olivier Mousis, Tobias Owen, Henri Rème, Thierry Sémon, Chia-Yu Tzou, Jack H. Martin Rubin, Kathrin Altwegg, Hans Balsiger, Akiva Bar-Nun, Jean-Jacques Berthelier, Christelle Briois, Ursina Calmonte, … Show All …, Michael Combi, Johan De Keyser, Björn Fiethe, Stephen A.