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Iron and nickel atoms in cometary atmospheres even far from the Sun
Jehin, E.; Manfroid, J.; Hutsemékers, D.
In comets, iron and nickel are found in refractory dust particles or in metallic and sulfide grains1. So far, no iron- or nickel-bearing molecules have been observed in the gaseous coma of comets2. Iron and a few other heavy atoms, such as copper and cobalt, have been observed only in two exceptional objects: the Great Comet …
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 …
An orbital water-ice cycle on comet 67P from colour changes
Longobardo, Andrea; Mottola, Stefano; Arnold, Gabriele +10 more
Solar heating of a cometary surface provides the energy necessary to sustain gaseous activity, through which dust is removed1,2. In this dynamical environment, both the coma3,4 and the nucleus5,6 evolve during the orbit, changing their physical and compositional properties. The environment around an active nucleus …
Eye of a skull reveals details of cometary materials
Asphaug, Erik
The Philae spacecraft was meant to anchor itself to the surface of the comet 67P/Churyumov-Gerasimenko, but instead bounced into a hidden grotto. The telltale markings of its passage reveal details of the comet's fragile boulders.
A homogeneous nucleus for comet 67P/Churyumov-Gerasimenko from its gravity field
Jorda, L.; Pätzold, M.; Sierks, H. +13 more
Cometary nuclei consist mostly of dust and water ice. Previous observations have found nuclei to be low-density and highly porous bodies, but have only moderately constrained the range of allowed densities because of the measurement uncertainties. Here we report the precise mass, bulk density, porosity and internal structure of the nucleus of come…
Aggregate dust particles at comet 67P/Churyumov-Gerasimenko
Jessberger, Elmar K.; Torkar, Klaus; Levasseur-Regourd, Anny-Chantal +9 more
Comets are thought to preserve almost pristine dust particles, thus providing a unique sample of the properties of the early solar nebula. The microscopic properties of this dust played a key part in particle aggregation during the formation of the Solar System. Cometary dust was previously considered to comprise irregular, fluffy agglomerates on …
Exposed water ice on the nucleus of comet 67P/Churyumov-Gerasimenko
Langevin, Y.; Bellucci, G.; Jaumann, R. +77 more
Although water vapour is the main species observed in the coma of comet 67P/Churyumov-Gerasimenko and water is the major constituent of cometary nuclei, limited evidence for exposed water-ice regions on the surface of the nucleus has been found so far. The absence of large regions of exposed water ice seems a common finding on the surfaces of many…
High-molecular-weight organic matter in the particles of comet 67P/Churyumov-Gerasimenko
Krüger, Harald; Haerendel, Gerhard; Langevin, Yves +39 more
The presence of solid carbonaceous matter in cometary dust was established by the detection of elements such as carbon, hydrogen, oxygen and nitrogen in particles from comet 1P/Halley. Such matter is generally thought to have originated in the interstellar medium, but it might have formed in the solar nebula—the cloud of gas and dust that was left…
Fission and reconfiguration of bilobate comets as revealed by 67P/Churyumov-Gerasimenko
Mottola, Stefano; Steckloff, Jordan; Naidu, Shantanu P. +6 more
The solid, central part of a comet—its nucleus—is subject to destructive processes, which cause nuclei to split at a rate of about 0.01 per year per comet. These destructive events are due to a range of possible thermophysical effects; however, the geophysical expressions of these effects are unknown. Separately, over two-thirds of comet nuclei th…
Mission accomplished: Rosetta crashes into comet
Gibney, Elizabeth
Craft sends back wealth of images in 19-kilometre descent.