DR-induced escape of O and C from early Mars

Zhao, Jie; Tian, Feng; Ni, Yufang

doi:10.1016/j.icarus.2016.11.021

Cited by 5 publications

(5 citation statements)

References 43 publications

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“…1) Photochemical escape. Neutrals that were produced through dissociative recombination -the photoionization of neutrals by the solar EUV irradiation with subsequent recombination of the ions into energetic neutrals -can eventually gain enough energy to reach escape velocity (Lammer and Bauer, 1991;Luhmann et al, 1992;Lammer et al, 1996Lammer et al, , 2006Fox and Hać, 1997;Chassefière and Leblanc, 2004;Zhao and Tian, 2015;Amerstorfer et al, 2017;Zhao et al, 2017).…”

Section: Volcanic Outgassingmentioning

confidence: 99%

“…Finally, photochemical escape at Mars was investigated by several different studies in the past (e.g., Fox, 2004;Gröller et al, 2014;Lee et al, 2015;Zhao and Tian, 2015;Amerstorfer et al, 2017;Lillis et al, 2017;Zhao et al, 2017), some of them also included -at least partially -the pre-Noachian into their study (Zhao and Tian, 2015;Amerstorfer et al, 2017;Zhao et al, 2017). While Zhao and Tian (2015) investigated the photochemical escape of oxygen with a focus on dissociative re- present-day value, it can be expected that a similar or even higher amount of CO2 could have potentially been lost from the atmosphere of Mars prior to 4.3 Ga. Photochemical escape can therefore not be neglected, if one wants to address the question of whether Mars had a dense atmosphere during the first ~400 million years or not.…”

Section: Non-thermal Escape Before 4 Gyr Agomentioning

confidence: 99%

“…Was an early CO2 atmosphere stable against the high EUV flux of the young Sun? -What role did non-thermal escape processes played on Mars during the first ~400-600 million years (Terada et al, 2009;Lammer et al, 2013;Amerstorfer et al, 2017;Zhao et al, 2017;B. M. Jakosky et al, 2018;Dong et al, 2018a;Sakata et al, 2020)?…”

Section: Introductionmentioning

confidence: 99%

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Did Mars Possess a Dense Atmosphere During the First $\sim400$ Million Years?

Scherf

Lämmer

2020

Space Sci Rev

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It is not yet entirely clear whether Mars began as a warm and wet planet that evolved towards the present-day cold and dry body or if it always was cold and dry with just some sporadic episodes of liquid water on its surface. An important clue into this question can be gained by studying the earliest evolution of the Martian atmosphere and whether it was dense and stable to maintain a warm and wet climate or tenuous and susceptible to strong atmospheric escape. In this review we therefore discuss relevant aspects for the evolution and stability of a potential early Martian atmosphere. This contains the EUV flux evolution of the young Sun, the formation timescale and volatile inventory of the planet including volcanic degassing, impact delivery and removal, the loss of the catastrophically outgassed steam atmosphere, atmosphere-surface interactions, as well as thermal and non-thermal escape processes affecting a potential secondary atmosphere at early Mars. While early non-thermal escape at Mars before 4 billion years ago is poorly understood, in particular in view of its ancient intrinsic magnetic field, research on thermal escape processes and the stability of a CO2-dominated atmosphere around Mars against high EUV fluxes indicate that volatile delivery and volcanic degassing cannot counterbalance the strong thermal escape. Therefore, a catastrophically

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Section: Volcanic Outgassingmentioning

confidence: 99%

Section: Non-thermal Escape Before 4 Gyr Agomentioning

confidence: 99%

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Did Mars Possess a Dense Atmosphere During the First $\sim400$ Million Years?

Scherf

Lämmer

2020

Space Sci Rev

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“…Estimates of the atomic O escape rate in the literature vary greatly from 10 24 s −1 to 10 26 s −1 depending on season and solar activity (Fox & Hać 2018, and references therein). Atomic C and N escape are less well studied, with estimated escape rates typically over the range of 10 23 s −1 to 10 24 s −1 (e.g., Fox 2004;Bakalian & Hartle 2006;Bakalian 2006;Gröller et al 2014;Zhao et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Photochemical escape of atomic C and N on Mars: clues from a multi-instrument MAVEN dataset

Cui

Jiang

et al. 2018

A&A

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Context. Photochemical escape of hot atoms is crucial to the long-term evolution of the Martian climate. For atomic C and N, photochemical escape is primarily driven by photodissociation (PD) of CO and N2. Aims. Combining the Mars Atmosphere and Volatile Evolution (MAVEN) measurements of atmospheric neutral densities and solar EUV/X-ray irradiance, we perform a state-of-the-art analysis of atomic C and N escape on Mars. Methods. For each MAVEN orbit, we calculated the hot C and N production rates in the dayside Martian upper atmosphere via PD, from which the escape rates are estimated using a simplified technique to parameterize the respective escape probabilities taking into account multiple collisions with ambient neutrals. Results. The mean C and N escape rates are 1 × 1024 s−1 and 9 × 1024 s−1, appropriate for low to moderate solar activity conditions, and thermospheric PD makes a larger contribution to the total N escape than to the total C escape. The above differences highlight the importance of nascent energy, with more energetic nascent escaping atoms able to survive collisions with ambient neutrals more easily, thus extending down to deeper regions of the atmosphere. Solar cycle variation in C and N escape is revealed by our analysis, whereas solar zenith angle variation is absent for both species. These results could be explained by the fact that the production of nascent escaping atoms responds to varying solar illumination angle at low altitudes where the escape probability is negligible, but responds to varying level of solar EUV/X-ray irradiance at high altitudes where the atmosphere is essentially collisionless.

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“…the recent study of Amerstorfer et al 2017) but might on the other hand also decrease at higher EUV fluxes due to an enhanced probability of collision between energetic and thermal atoms in an expanded upper atmosphere (see e.g. another recent study on Mars by Zhao et al 2017). Also, the complex ion chemistry that produces suprathermal nitrogen atoms should have been different in the past, since CH4 likely was not available in similar abundances than at present-day over the whole history of Titan.…”

Section: Nitrogen Escape Through Timementioning

confidence: 97%

Escape and evolution of Titan's N$_2$ atmosphere constrained by $^{14}$N/$^{15}$N isotope ratios

Erkaev,

Scherf,

Thaller

et al. 2020

Preprint

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We apply a 1D upper atmosphere model to study thermal escape of nitrogen over Titan's history. Significant thermal escape should have occurred very early for solar EUV fluxes 100 to 400 times higher than today with escape rates as high as ≈ 1.5 × 10 28 s −1 and ≈ 4.5×10 29 s −1 , respectively, while today it is ≈ 7.5×10 17 s −1 . Depending on whether the Sun originated as a slow, moderate or fast rotator, thermal escape was the dominant escape process for the first 100 to 1000 Myr after the formation of the solar system. If Titan's atmosphere originated that early, it could have lost between ≈ 0.5 − 16 times its present atmospheric mass depending on the Sun's rotational evolution. We also investigated the mass-balance parameter space for an outgassing of Titan's nitrogen through decomposition of NH 3 -ices in its deep interior. Our study indicates that, if Titan's atmosphere originated at the beginning, it could have only survived until today if the Sun was a slow rotator. In other cases, the escape would have been too strong for the degassed nitrogen to survive until presentday, implying later outgassing or an additional nitrogen source. An endogenic origin of Titan's nitrogen partially through NH 3 -ices is consistent with its initial fractionation of 14 N/ 15 N ≈ 166 -172, or lower if photochemical removal was relevant for longer than the last ≈ 1,000 Myr. Since this ratio is slightly above the ratio of cometary ammonia, some of Titan's nitrogen might have originated from refractory organics.

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DR-induced escape of O and C from early Mars

Cited by 5 publications

References 43 publications

Did Mars Possess a Dense Atmosphere During the First $\sim400$ Million Years?

Did Mars Possess a Dense Atmosphere During the First $\sim400$ Million Years?

Photochemical escape of atomic C and N on Mars: clues from a multi-instrument MAVEN dataset

Escape and evolution of Titan's N$_2$ atmosphere constrained by $^{14}$N/$^{15}$N isotope ratios

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