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Ammonium salts are a reservoir of nitrogen on a cometary nucleus and possibly on some asteroids
Longobardo, Andrea; Palomba, Ernesto; Schmitt, Bernard +29 more
The measured nitrogen-to-carbon ratio in comets is lower than for the Sun, a discrepancy which could be alleviated if there is an unknown reservoir of nitrogen in comets. The nucleus of comet 67P/Churyumov-Gerasimenko exhibits an unidentified broad spectral reflectance feature around 3.2 micrometers, which is ubiquitous across its surface. On the …
Evidence of ammonium salts in comet 67P as explanation for the nitrogen depletion in cometary comae
De Keyser, Johan; Gombosi, Tamas I.; Berthelier, Jean-Jacques +14 more
Cometary comae are generally depleted in nitrogen. The main carriers for volatile nitrogen in comets are NH3 and HCN. It is known that ammonia readily combines with many acids, such as HCN, HNCO and HCOOH, encountered in the interstellar medium as well as in cometary ice to form ammonium salts (NH4+X-) a…
ALMA and ROSINA detections of phosphorus-bearing molecules: the interstellar thread between star-forming regions and comets
Altwegg, K.; Balsiger, H.; Berthelier, J. J. +20 more
To understand how phosphorus (P)-bearing molecules are formed in star-forming regions, we have analysed the Atacama Large Millimeter/Submillimeter Array (ALMA) observations of PN and PO towards the massive star-forming region AFGL 5142, combined with a new analysis of the data of the comet 67P/Churyumov-Gerasimenko taken with the Rosetta Orbiter S…
Dust-to-Gas and Refractory-to-Ice Mass Ratios of Comet 67P/Churyumov-Gerasimenko from Rosetta Observations
Pätzold, Martin; Choukroun, Mathieu; Thomas, Nicolas +9 more
This chapter reviews the estimates of the dust-to-gas and refractory-to-ice mass ratios derived from Rosetta measurements in the lost materials and the nucleus of 67P/Churyumov-Gerasimenko, respectively. First, the measurements by Rosetta instruments are described, as well as relevant characteristics of 67P. The complex picture of the activity of …
How comets work: nucleus erosion versus dehydration
Blum, J.; Güttler, C.; Gundlach, B. +3 more
We develop an activity model based on ice sublimation and gas diffusion inside cm-sized pebbles making-up a cometary nucleus. Our model explains cometary activity assuming no free parameters and fixing the nucleus surface temperature Ts, its gradient below the nucleus surface at thermal equilibrium, the pressure inside the porous pebble…
The gas production of 14 species from comet 67P/Churyumov-Gerasimenko based on DFMS/COPS data from 2014 to 2016
Altwegg, Kathrin; Rubin, Martin; Läuter, Matthias +1 more
The coma of comet 67P/Churyumov-Gerasimenko has been probed by the Rosetta spacecraft and shows a variety of different molecules. The ROSINA COmet Pressure Sensor and the Double Focusing Mass Spectrometer provide in situ densities for many volatile compounds including the 14 gas species H2O, CO2, CO, H2S, O2
Infrared detection of aliphatic organics on a cometary nucleus
Bellucci, G.; Carlson, R. W.; Fornasier, S. +28 more
The European Space Agency's Rosetta mission1 has acquired unprecedented measurements of the surface of the nucleus of comet 67P/Churyumov-Gerasimenko (hereafter, 67P), the composition of which, as determined by in situ and remote-sensing instruments, including the VIRTIS instrument2, seems to be an assemblage of ices, mineral…
On the activity of comets: understanding the gas and dust emission from comet 67/Churyumov-Gerasimenko's south-pole region during perihelion
Blum, J.; Fulle, M.; Gundlach, B.
When comets approach the Sun, their surface is heated and the volatile species start to sublimate. Due to the increasing gas pressure, dust is ejected off the surface, which can be observed as cometary coma, dust tail, and trail. However, the underlying physical processes are not fully understood. Using state-of-the-art results for the transport o…
The Philae lander reveals low-strength primitive ice inside cometary boulders
Parker, Joel Wm.; Auster, Hans-Ulrich; Heinisch, Philip +25 more
On 12 November 2014, the Philae lander descended towards comet 67P/Churyumov-Gerasimenko, bounced twice off the surface, then arrived under an overhanging cliff in the Abydos region. The landing process provided insights into the properties of a cometary nucleus1-3. Here we report an investigation of the previously undiscovered site of …
On the Origin and Evolution of the Material in 67P/Churyumov-Gerasimenko
Morbidelli, Alessandro; Snodgrass, Colin; Altwegg, Kathrin +5 more
Primitive objects like comets hold important information on the material that formed our solar system. Several comets have been visited by spacecraft and many more have been observed through Earth- and space-based telescopes. Still our understanding remains limited. Molecular abundances in comets have been shown to be similar to interstellar ices …