Xenon isotopes in 67P/Churyumov-Gerasimenko show that comets contributed to Earth's atmosphere

Marty, Bernard; Altwegg, Kathrin; Balsiger, H.; Bar‐Nun, A.; Bekaert, David V.; Berthelier, J. J.; Bieler, André; Briois, C.; Calmonte, Ursina; Combi, M. R.; Keyser, Johan De; Fiethe, Björn; Fuselier, S. A.; Gombosi, T. I.; Hansen, K. C.; Hässig, Myrtha; Jäckel, A.; Kopp, E.; Korth, A.; Roy, Léna Le; Mall, U.; Mousis, O.; Owen, Tobias; Rème, H.; Rubin, Martin; Sémon, Thierry; Tzou, Chia-Yu; Waite, J. H.; Würz, Peter

doi:10.1126/science.aal3496

Cited by 193 publications

(240 citation statements)

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“…It has been concluded that the difference between solid and volatile phase points to a not-homogenized protosolar nebula from which comets are thought to have emerged. This is supported by the detection of non-solar isotopic ratio for xenon (Marty 2017) and Si (Rubin 2017) in comet 67P by ROSINA.…”

Section: O N C L U S I O Nmentioning

confidence: 53%

“…This however would be hard to explain. ROSINA has detected a non-solar isotopic ratio for xenon (Marty 2017) as well as for Si (Rubin 2017) in comet 67P, which points to a non-homogeneously mixed protosolar nebula. In addition, a high D 2 O/HDO versus HDO/H 2 O ratio (Altwegg 2017) and molecular oxygen, which seems to be very well embedded in water (Bieler et al 2015), have been measured in the coma of 67P.…”

Section: Discussionmentioning

confidence: 99%

“…ROSINA has been sampling the volatiles in the coma throughout the mission. ROSINA observations revealed some remarkable links to pre-solar ices, including elevated D/H ratios in singly and doubly deuterated water (Altwegg et al 2015;Altwegg 2017), a remarkable abundance of molecular oxygen, O 2 , well correlated to H 2 O and possibly inherited from irradiated interstellar ice grains (Bieler et al 2015), and xenon isotopic ratios different from solar (Marty 2017).…”

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confidence: 99%

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Sulphur isotope mass-independent fractionation observed in comet 67P/Churyumov–Gerasimenko by Rosetta/ROSINA

Calmonte

Altwegg

Balsiger

et al. 2017

Monthly Notices of the Royal Astronomical Society

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The knowledge about sulphur isotopic fractionation in volatile cometary species is limited as only measurements in five comets have been done and only for 34 S/ 32 S. The lack of information about the fractionation of 33 S/ 32 S makes it impossible to compare them with what is known from refractories. We present results of 34 S/ 32 S and for the first time 33 S/ 32 S isotopic ratio in H 2 S, OCS, and CS 2 in the coma of comet 67P/Churyumov-Gerasimenko. Observations used for this study were performed with Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/Double Focusing Mass Spectrometer during 2014 October and 2016 May. Bulk isotopic 33 S/ 32 S and 34 S/ 32 S ratios derived from these three species yield δ 33 S = (−302 ± 29) and δ 34 S = (−41 ± 17) , respectively. The observed isotopic fractionation is significantly different from the assumed Solar system standard [Vienna-Canyon Diablo Troilite (V-CDT)] and all other reported values for Solar system objects, except other comets. Furthermore, we show that neither mass-dependent nor mass-independent fractionation due to photodissociation as it has been observed in recent laboratory studies can be the cause of the significant depletion compared to Solar system standard. In addition, we conclude that there seems to be an intrinsic difference in sulphur isotopic fractionation in cometary volatiles and refractories while the difference between molecules is most likely due to different chemical pathways. The significant fractionation of sulphur isotopes together with a high D 2 O/HDO versus HDO/H 2 O and non-solar isotopic ratio for xenon as well as for Si point towards a non-homogeneously mixed protosolar nebula.Key words: comets: general -comets: individual: 67P/Churyumov-Gerasimenko. I N T RO D U C T I O NRosetta is a mission of the European Space Agency (ESA) with the aim to characterize Jupiter-family comet 67P/ChuryumovGerasimenko (hereafter 67P) in situ. Rosetta followed the comet from a heliocentric distance of more than 3.6 au to perihelion and finally away again from the Sun to almost 3.8 au. One of the science goals of Rosetta was the determination of the elemental, isotopic, E-mail: ursina.calmonte@space.unibe.ch (UC); kathrin.altwegg@space. unibe.ch (KA); martin.rubin@space.unibe.ch (MR) and molecular composition of the cometary material. Most of the composition measurements during the mission, especially isotopic measurements, were done from the Rosetta orbiter in the coma, by the instrument ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis; Balsiger et al. 2007) Sensor (COPS). The composition of the coma, including dust and gas, depends on the actual composition of the nucleus and the physical and chemical processes involved in the desorption, sublimation and transport of the material into the coma. ROSINA has been sampling the volatiles in the coma throughout the mission. ROSINA observations revealed some remarkable links to pre-solar ices, including elevated D/H ratios in singly and doubly deuterated water (Altwegg ...

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Section: O N C L U S I O Nmentioning

confidence: 53%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Sulphur isotope mass-independent fractionation observed in comet 67P/Churyumov–Gerasimenko by Rosetta/ROSINA

Calmonte

Altwegg

Balsiger

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…Coupled with noble gas measurements from the returned sample, we would be able to determine the likelihood that the MBCs are the sources of Earth's water. We could also be able to constrain the cometary contribution further, complementing results based on Rosetta data (Marty et al, 2016(Marty et al, , 2017. In each case, when combined with data from the sample return and in-situ study performed by Caroline, we would be provided with information to help constrain where in the Solar System the MBCs formed relative to comets, S-and C-type asteroids.…”

Section: Introductionmentioning

confidence: 94%

The proposed Caroline ESA M3 mission to a Main Belt Comet

Jones

Agarwal

Bowles

et al. 2018

Advances in Space Research

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We describe Caroline, a mission proposal submitted to the European Space Agency in 2010 in response to the Cosmic Visions M3 call for medium-sized missions. Caroline would have travelled to a Main Belt Comet (MBC), characterizing the object during a flyby, and capturing dust from its tenuous coma for return to Earth. MBCs are suspected to be transition objects straddling the traditional boundary between volatile-poor rocky asteroids and volatile-rich comets. The weak cometary activity exhibited by these objects indicates the presence of water ice, and may represent the primary type of object that delivered water to the early Earth. The Caroline mission would have employed aerogel as a medium for the capture of dust grains, as successfully used by the NASA Stardust mission to Comet 81P/ Wild 2. We describe the proposed mission design, primary elements of the spacecraft, and provide an overview of the science instruments and their measurement goals. Caroline was ultimately not selected by the European Space Agency during the M3 call; we briefly reflect on the pros and cons of the mission as proposed, and how current and future mission MBC mission proposals such as Castalia could best be approached.

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“…Also important is to develop a relatively simple scenario, trying to follow the Occam's razor and avoid speculative hypothetical approaches. The sources and processes responsible for delivery of major volatile elements, mainly concentrated in the atmo-hydrosphere, are not considered here and the readers can find the respective data and discussions in recent papers by Marty [2012], Albarede et al [2013], Dauphas and Morbidelli [2014], Marty et al [2016Marty et al [ , 2017, FischerGödde and Kleine [2017].…”

Section: Terrestrial Reservoirsmentioning

confidence: 99%

The late Earth's accretion: Processes and materials

Tolstikhin¹

2018

Russ. J. Earth Sci.

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In accord with the standard Earth accretion scenario, the late accretion supervened the last collision with a massive proto-planet, segregation of the core, and (partial) solidification of the magma ocean. These processes took place ≈ 40 Ma after Sun formation or somewhat later. Traces of the processes and respective materials have been preserved as specific elemental and isotopic abundances in the earth's mantle. Pu-238 U-129 I-Xe systematics trace the accreting materials and the rate of mantle mixing and degassing. Recently proposed interpretations of this last systematics appear to be precarious and are particularly discussed in this contribution. During the late accretion a terrestrial regolith, including chondritic and solar-wind-irradiated materials, was rapidly accumulating on the surface of the early thick basaltic crust, enriched in incompatible elements. This early crust had not been preserved. Its overturn(s) into the mantle during several 100th Ma after Sun formation and (partial) isolation from the mantle convection allow all principal observations, related to the informative systematics mentioned above, to be satisfied, providing the transfer of the crust®olith "cake" was not accompanying by fractionation and degassing, in contrast to present-day slab subduction.

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Xenon isotopes in 67P/Churyumov-Gerasimenko show that comets contributed to Earth's atmosphere

Cited by 193 publications

References 33 publications

Sulphur isotope mass-independent fractionation observed in comet 67P/Churyumov–Gerasimenko by Rosetta/ROSINA

Sulphur isotope mass-independent fractionation observed in comet 67P/Churyumov–Gerasimenko by Rosetta/ROSINA

The proposed Caroline ESA M3 mission to a Main Belt Comet

The late Earth's accretion: Processes and materials

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