Evidence that Pluto’s atmosphere does not collapse from occultations including the 2013 May 04 event

Olkin, C. B.; Young, L. A.; Borncamp, David; Pickles, Andrew; Sicardy, B.; Assafin, M.; Bianco, Federica; Buie, M. W.; Oliveira, A. Dias de; Gillon, M.; French, R. G.; Gomes, A. Ramos; Jehin, Emmanuël; Morales, N.; Opitom, Cyrielle; Ortiz, J. L.; Maury, A.; Norbury, M.; Braga-Ribas, F.; Smith, Richard Currie; Wasserman, L. H.; Young, E. F.; Zacharias, M. I.; Zacharias, N.

doi:10.1016/j.icarus.2014.03.026

Cited by 55 publications

(41 citation statements)

References 22 publications

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“…These results suggest that the southern hemisphere of Pluto is not entirely covered by N 2 -rich ice, otherwise the peak surface pressure would have occurred much earlier than 2015 (a similar result is found in Young (2013); Olkin et al (2015)). At most, a thin mid-latitude band of N 2 -rich ice (similar to that observed in the northern hemisphere) could be present in the southern hemisphere in 2015.…”

Section: Summary Of Simulation Resultssupporting

confidence: 65%

The nitrogen cycles on Pluto over seasonal and astronomical timescales

Bertrand

Forget

Umurhan

et al. 2018

Icarus

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Pluto's surface is covered in numerous CH 4 ice deposits, that vary in texture and brightness, as revealed by the New Horizons spacecraft as it flew by Pluto in July 2015. These observations suggest that CH 4 on Pluto has a complex history, involving reservoirs of different composition, thickness and stability controlled by volatile processes occurring on different timescales. In order to interpret these observations, we use a Pluto volatile transport model able to simulate the cycles of N 2 and CH 4 ices over millions of years. By assuming fixed solid mixing ratios, we explore how changes in surface albedos, emissivities and thermal inertias impact volatile transport. This work is therefore a direct and natural continuation of the work by , which only explored the N 2 cycles. Results show that bright CH 4 deposits can create cold traps for N 2 ice outside Sputnik Planitia, leading to a strong coupling between the N 2 and CH 4 cycles. Depending on the assumed albedo for CH 4 ice, the model predicts CH 4 ice accumulation (1) at the same equatorial latitudes where the Bladed Terrain Deposits are observed, supporting the idea that these CH 4 -rich deposits are massive and perennial, or (2) at mid-latitudes (25 • -70 • ), forming a thick mantle which is consistent with New Horizons observations. In our simulations, both CH 4 ice reservoirs are not in an equilibrium state and either one can dominate the other over long timescales, depending on the assumptions made for the CH 4 albedo. This suggests that long-term volatile transport exists between the observed reservoirs. The model also reproduces the formation of N 2 deposits at mid-latitudes and in the equatorial depressions surrounding the Bladed Terrain Deposits, as observed by New Horizons. At the poles, only seasonal CH 4 and N 2 deposits are obtained in Pluto's current orbital configuration. Finally, we show that Pluto's atmosphere always contained, over the last astronomical cycles, enough gaseous CH 4 to absorb most of the incoming Lyman-α flux.

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Section: Summary Of Simulation Resultssupporting

confidence: 65%

The nitrogen cycles on Pluto over seasonal and astronomical timescales

Bertrand

Forget

Umurhan

et al. 2018

Icarus

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“…Assuming Pluto's current escape rate is fairly constant on time scales of years, we can expect that the size of the interaction region, which we assume was particularly compressed under the unusually high solar wind ram pressure at the time of the New Horizons flyby, ranges from the current size of a few planetary radii to as much as~25 Pluto radii under low solar wind ram pressures. Extrapolating from the atmospheric escape conditions at Pluto forward or backward in time is particularly complicated because of the complex seasonal patterns of a system that is both tilted on its side as well as in an eccentric orbit [Young, 2013;Olkin et al, 2014Olkin et al, , 2015Hansen et al, 2015]. But it is quite possible that at very low escape rates the interaction becomes more like the moon with the solar wind impinging direction on the icy surface, while at high escape rates the interaction may be more cometary.…”

Section: Plutomentioning

confidence: 99%

Atmospheric escape from unmagnetized bodies

Brain

Bagenal

et al. 2016

J. Geophys. Res. Planets

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The upper atmospheres of unmagnetized solar system bodies interact more directly with their local plasma environment than their counterparts on magnetized bodies such as Earth. One consequence of this interaction is that atmospheric particles can gain energy from the flowing plasma, as well as solar photons, and escape to space. Escape proceeds through a number of different mechanisms that can remove neutral particles (Jeans escape, photochemical escape, and sputtering) and mechanisms that can remove ions (ion pickup, magnetic shear and tension‐related escape, and pressure gradients). Here we discuss the plasma interactions and escape processes and rates from five solar system objects spanning 3 orders of magnitude in size: comets, Pluto, Titan, Mars, and Venus. We describe similarities and differences in escape for the different objects and provide four open questions that should be addressed in the coming years.

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“…This was initially modeled for Triton and Pluto (see reviews by Spencer et al 1997 andYelle et al 1995). Since those reviews, trends of increasing atmospheric pressure for both Triton and Pluto were observed using the technique of stellar occultation, with an increase by factors of two and three respectively (Elliot et al 1998;Elliot et al 2000;Elliot et al 2003a;Olkin et al 1997Olkin et al , 2015Meza et al 2019; see section 6). The new time-base of atmospheric observations and the New Horizons flyby of Pluto inspired new models of seasonal variation (e.g., Young 2012Young , 2013Young , 2017Hansen et al 2015;Olkin et al 2015), including general circulation models (e.g., Forget et al 2017) and evolution of atmospheres on the timescale of millions of years (e.g., Bertrand et al 2016Bertrand et al , 2018.…”

Section: Variation Of Atmospheres Over An Orbitmentioning

confidence: 99%

Volatile evolution and atmospheres of Trans-Neptunian objects

Young

Braga-Ribas

Johnson

2020

The Trans-Neptunian Solar System

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At 30-50 K, the temperatures typical for surfaces in the Kuiper Belt (e.g. Stern & Trafton 2008), only seven species have sublimation pressures higher than 1 nbar (Fray & Schmitt 2009): Ne, N 2 , CO, Ar, O 2 , CH 4 , and Kr. Of these, N 2 , CO, and CH 4 have been detected or inferred on the surfaces of Trans-Neptunian Objects (TNOs). The presence of tenuous atmospheres above these volatile ices depends on the sublimation pressures, which are very sensitive to the composition, temperatures, and mixing states of the volatile ices. Therefore, the retention of volatiles on a TNO is related to its formation environment and thermal history. The surface volatiles may be transported via seasonally varying atmospheres and their condensation might be responsible for the high surface albedos of some of these bodies. The most sensitive searches for tenuous atmospheres are made by the method of stellar occultation, which have been vital for the study of the atmospheres of Triton and Pluto, and has to-date placed upper limits on the atmospheres of 11 other bodies. The recent release of the Gaia astrometric catalog has led to a "golden age" in the ability to predict TNO occultations in order to increase the observational data base.

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Evidence that Pluto’s atmosphere does not collapse from occultations including the 2013 May 04 event

Cited by 55 publications

References 22 publications

The nitrogen cycles on Pluto over seasonal and astronomical timescales

The nitrogen cycles on Pluto over seasonal and astronomical timescales

Atmospheric escape from unmagnetized bodies

Volatile evolution and atmospheres of Trans-Neptunian objects

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