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N delivered by comets to Pluto. a. The total delivered N per impactor size assuming an N fraction of (0.02), which gives an upper limit to what may be converted to N 2 on Pluto. b. Results from Equation (3) showing N delivered per year as a function of comet size. Integrating over comet size yields the total mass delivered per year.
Source publication
N2 is abundant in Pluto's atmosphere and on its surface, but the supply is
depleted by prodigious atmospheric escape. We demonstrate that cometary impacts
could not have delivered enough N2 mass to resupply Pluto's atmospheric escape
over time; thus Pluto's N2 is likely endogenous, and therefore was either
acquired early in its history or created b...
Contexts in source publication
Context 1
... quite volatile, this specific molecule may be depleted in comets. In this paper we will consider the total nitrogen mass (i.e. N in all forms) per impactor by simply multiplying the volume of a spherical impactor (4/3)í µí¼(í µí± * 1000/2) 3 , by the overall density (1000 kgm -3 ), and the highest N fraction estimates (0.02), for an upper limit (Fig. 1a). We then estimate the mass of impactor- delivered N to Pluto per year (Fig. 1b), by multiplying equation (2) by the N mass per ...
Context 2
... we will consider the total nitrogen mass (i.e. N in all forms) per impactor by simply multiplying the volume of a spherical impactor (4/3)í µí¼(í µí± * 1000/2) 3 , by the overall density (1000 kgm -3 ), and the highest N fraction estimates (0.02), for an upper limit (Fig. 1a). We then estimate the mass of impactor- delivered N to Pluto per year (Fig. 1b), by multiplying equation (2) by the N mass per ...
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I am not an author, but one of the Endorsers. This is a remarkable and interesting proposal and needs to be spread.
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Citations
... For even the lowest estimates of its surface temperature at aphelion (27 K), this thermal gradient implies that a N 2 deposits thicker than ∼ 1.4 km would be sufficient to melt N 2 at its base. Adopting the same cosmogonic nitrogen mass fraction suggested for Pluto by Singer & Stern (2015), Eris likely contained an initial interior reservoir of ∼ 5×10 19 kg of nitrogen, enough to create a global N 2 surface layer ∼ 3 km thick, if internal processes ever liberated this material and delivered it to the surface. The ratio of layer thicknesses required to support convection on two different worlds is ...
The Pluto system is an archetype for the multitude of icy dwarf planets and accompanying satellite systems that populate the vast volume of the solar system beyond Neptune. New Horizons' exploration of Pluto and its five moons gave us a glimpse into the range of properties that their kin may host. Furthermore, the surfaces of Pluto and Charon record eons of bombardment by small trans-Neptunian objects, and by treating them as witness plates we can infer a few key properties of the trans-Neptunian population at sizes far below current direct-detection limits. This chapter summarizes what we have learned from the Pluto system about the origins and properties of the trans-Neptunian populations, the processes that have acted upon those members over the age of the solar system, and the processes likely to remain active today. Included in this summary is an inference of the properties of the size distribution of small trans-Neptunian objects and estimates on the fraction of binary systems present at small sizes. Further, this chapter compares the extant properties of the satellites of trans-Neptunian dwarf planets and their implications for the processes of satellite formation and the early evolution of planetesimals in the outer solar system. Finally, this chapter concludes with a discussion of near-term theoretical, observational, and laboratory efforts that can further ground our understanding of the Pluto system and how its properties can guide future exploration of trans-Neptunian space.
... These and further studies (e.g. Young et al. 1997;Lellouch et al. 2011;Olkin et al. 2014;Bosh et al. 2015;Dias-Oliveira et al. 2015) showed that the main constituent of its atmosphere was N 2 which was recently confirmed by the New Horizons space mission (Stern et al. 2015;Gladstone et al. 2016). Contrary to Titan, however, Pluto's tenuous atmosphere only has a surface pressure of about 6-24 µbar depending on its orbital location (Young et al. 1997;Lellouch et al. 2011). ...
... While it was debated whether this escape might be hydrodynamic (Krasnopolsky 1999;Tian and Toon 2005;Strobel 2008) with loss rates of up to 10 27 -10 28 molecules s −1 (Tian and Toon 2005;Zhu et al. 2014), or enhanced Jeans escape , New Horizons showed that its atmosphere is currently lost via Jeans escape with the loss rate being in the range of ∼10 23 molecules s −1 . Based on the pre-New Horizons escape models, Singer and Stern (2015) suggested that Pluto's N 2 should be of endogenic origin, if the estimated escape rates would have been so high that cometary impacts could not have resupplied its atmospheric N 2 . In this case internal processes would be needed to outgas N 2 from the interior into the atmosphere (Singer and Stern 2015). ...
... Based on the pre-New Horizons escape models, Singer and Stern (2015) suggested that Pluto's N 2 should be of endogenic origin, if the estimated escape rates would have been so high that cometary impacts could not have resupplied its atmospheric N 2 . In this case internal processes would be needed to outgas N 2 from the interior into the atmosphere (Singer and Stern 2015). A post-New Horizons model by Glein and Waite (2018) considered whether the reservoir of Pluto's N 2 might be of primordial origin for which they developed two different model approaches, i.e. i) a "cometary model" which assumes a composition similar to comets with trapped N 2 from the solar nebula, and ii) a "solar model" which assumes solar abundances of N 2 . ...
This brief review will discuss the current knowledge on the origin and evolution of the nitrogen atmospheres of the icy bodies in the solar system, particularly of Titan, Triton and Pluto. An important tool to analyse and understand the origin and evolution of these atmospheres can be found in the different isotopic signatures of their atmospheric constituents. The 14N/15N ratio of the N2-dominated atmospheres of these bodies serve as a footprint of the building blocks from which Titan, Triton and Pluto originated and of the diverse fractionation processes that shaped these atmospheres over their entire evolution. Together with other measured isotopic and elemental ratios such as 12C/13C or 36Ar/N2 these atmospheres can give important insights into the history of the icy bodies in the solar system, the diverse processes that affect their N2-dominated atmospheres, and the therewith connected solar activity evolution. Titan’s gaseous envelope most likely originated from ammonia ices with possible contributions from refractory organics. Its isotopic signatures can yet be seen in the – compared to Earth – comparatively heavy 14N/15N ratio of 167.7, even though this value slightly evolved over its history due to atmospheric escape and photodissociation of N2. The origin and evolution of Pluto’s and Triton’s tenuous nitrogen atmospheres remain unclear, even though it might be likely that their atmospheres originated from the protosolar nebula or from comets. An in-situ space mission to Triton such as the recently proposed Trident mission, and/or to the ice giants would be a crucial cornerstone for a better understanding of the origin and evolution of the icy bodies in the outer solar system and their atmospheres in general. Due to the importance of the isotopic measurements for understanding the origin and evolution of the icy bodies in the solar system, this review will also give a brief discussion on the diverse isotope measurement techniques with a focus on nitrogen.
... However, one should keep in mind that this range could be a serious underestimate as it excludes any subsurface reservoirs (e.g., N2 liquid trapped in crustal pore space [cf. Table 1]; N2 trapped as clathrate in Pluto's ice shell, N2 dissolved in a subsurface water ocean), and does not account for possible N2 loss from the Charon-forming giant impact, or added by later cometary bombardment (the latter perhaps 2×10 17 mol; Singer and Stern, 2015). ...
... That we even observe CO at all means that not all of Pluto's initial endowment of primordial CO need be aqueously processed (which seems plausible as volatile outgassing should have occurred before ice melting on the Pluto progenitors; Section 2.4), plus there is always the later input from Kuiper belt bombardment. Indeed, Glein and Waite (2018) estimate, based on Singer and Stern (2015), that Pluto's surface CO could have been completely supplied by comets over geologic time. (2018) Further work on such possible fractionation is warranted, however. ...
The Pluto-Charon system provides a broad variety of constraints on planetary formation, composition, chemistry, and evolution. Pluto was the first body to be discovered in what is now known as the Kuiper belt, its orbit ultimately becoming a major clue that the giant planets underwent substantial orbital migration early in Solar System history. This migration has been linked to an early instability in the orbits of the giant planets and the formation of the Kuiper belt itself, from an ancestral trans-Neptunian planetesimal disk that included Pluto. Pluto-Charon is emblematic of what are now recognized as small or dwarf planets. Far from being a cold, dead, battered icy relic, Pluto displays evidence of a complex geological history, with ongoing processes including tectonism, cryovolcanism, solid-state convection, glacial flow, atmospheric circulation, surface-atmosphere volatile exchange, aeolian processes, and atmospheric photochemistry, microphysics, and haze formation. Despite Pluto's relatively modest scale, the combination of original accretional heat, long-term internal radiogenic heat release, and external solar forcing, when combined with sufficiently volatile (and thus mobile) materials, yields an active world. Pluto may have inherited a large organic mass fraction during accretion, which may responsible, in part, for its surface and atmospheric volatiles. Charon, Pluto's major moon, displays evidence of extensive early tectonism and cryovolcanism. Dwarf planets are thus truly planetary in terms of satellite systems and geological and atmospheric complexity (if not ongoing activity). What they may lack in mass is made up in number, and the majority of the Solar System's dwarf planets remain undiscovered.
... These and further studies (e.g. Young et al. 1997;Lellouch et al. 2011;Olkin et al. 2014;Bosh et al. 2015;Dias-Oliveira et al. 2015) showed that the main constituent of its atmosphere was N 2 which was recently confirmed by the New Horizons space mission (Stern et al. 2015;Gladstone et al. 2016). Contrary to Titan, however, Pluto's tenuous atmosphere only has a surface pressure of about 6-24 µbar depending on its orbital location (Young et al. 1997;Lellouch et al. 2011). ...
... While it was debated whether this escape might be hydrodynamic (Krasnopolsky 1999;Tian and Toon 2005;Strobel 2008) with loss rates of up to 10 27 -10 28 molecules s −1 (Tian and Toon 2005;Zhu et al. 2014), or enhanced Jeans escape , New Horizons showed that its atmosphere is currently lost via Jeans escape with the loss rate being in the range of ∼10 23 molecules s −1 . Based on the pre-New Horizons escape models, Singer and Stern (2015) suggested that Pluto's N 2 should be of endogenic origin, if the estimated escape rates would have been so high that cometary impacts could not have resupplied its atmospheric N 2 . In this case internal processes would be needed to outgas N 2 from the interior into the atmosphere (Singer and Stern 2015). ...
... Based on the pre-New Horizons escape models, Singer and Stern (2015) suggested that Pluto's N 2 should be of endogenic origin, if the estimated escape rates would have been so high that cometary impacts could not have resupplied its atmospheric N 2 . In this case internal processes would be needed to outgas N 2 from the interior into the atmosphere (Singer and Stern 2015). A post-New Horizons model by Glein and Waite (2018) considered whether the reservoir of Pluto's N 2 might be of primordial origin for which they developed two different model approaches, i.e. i) a "cometary model" which assumes a composition similar to comets with trapped N 2 from the solar nebula, and ii) a "solar model" which assumes solar abundances of N 2 . ...
This brief review will discuss the current knowledge on the origin and evolution of the nitrogen atmospheres of the icy bodies in the solar system, particularly of Titan, Triton and Pluto. An important tool to analyse and understand the origin and evolution of these atmospheres can be found in the different isotopic signatures of their atmospheric constituents. The $^{14}$N/$^{15}$N ratio of the N$_2$-dominated atmospheres of these bodies serve as a footprint of the building blocks from which Titan, Triton and Pluto originated and of the diverse fractionation processes that shaped these atmospheres over their entire evolution. Together with other measured isotopic and elemental ratios such as $^{12}$C/$^{13}$C or Ar/N these atmospheres can give important insights into the history of the icy bodies in the solar system, the diverse processes that affect their N$_2$-dominated atmospheres, and the therewith connected solar activity evolution. Titan's gaseous envelope most likely originated from ammonia ices with possible contributions from refractory organics. Its isotopic signatures can yet be seen in the - compared to Earth - comparatively heavy $^{14}$N/$^{15}$N ratio of 167.7, even though this value slightly evolved over its history due to atmospheric escape and photodissociation of N$_2$. The origin and evolution of Pluto's and Triton's tenuous nitrogen atmospheres remain unclear, even though it might be likely that their atmospheres originated from the protosolar nebula or from comets. An in-situ space mission to Triton such as the recently proposed Trident mission, and/or to the ice giants would be a crucial cornerstone for a better understanding of the origin and evolution of the icy bodies in the outer solar system and their atmospheres in general.
... Figure 1 illustrates the tension between the ground-based and the New Horizons measurements of TNO size distributions. In this figure, the y-axis plots R(D)=N/(D −3 (D up −D low ) as in Singer et al. (2019); N is the number of objects in a mass bin with maximum diameter D up , minimum diameter D low , and central diameter D. We adopt a simple relation between impactor diameter D and crater diameter, D c , D=D c /6.25, which neglects the slightly steeper than linear relation between D and D c and represents a compromise among relations for different materials (e.g., Holsapple 1993;Housen & Holsapple 2011;Singer et al. 2013Singer et al. , 2019Singer & Stern 2015). In figures derived from analytic theory or numerical calculations later in this paper, we use the radius r=D/2 and r=(r low r up ) 1/2 ; R(r)=N/(r −3 (r up −r low ) and R(D)=4R(r). ...
We consider whether equilibrium size distributions from collisional cascades match the frequency of impactors derived from New Horizons crater counts on Charon. Using an analytic model and a suite of numerical simulations, we demonstrate that collisional cascades generate wavy size distributions; the morphology of the waves depends on the binding energy of solids and the collision velocity v c . For an adopted minimum size of solids, = 1 μ m, and collision velocity v c = 1–3 km s ⁻¹ , the waves are rather insensitive to the gravitational component of . If the bulk strength component of is for particles with radius r , size distributions with small Q s are much wavier than those with large Q s ; systems with e s ≈ −0.4 have stronger waves than systems with e s ≈ 0. Detailed comparisons with the New Horizons data suggest that a collisional cascade among solids with a bulk strength intermediate between weak ice and normal ice produces size distributions fairly similar to that of impactors on Charon. If the surface density Σ of the protosolar nebula varies with semimajor axis a as Σ ≈ 30 g cm ⁻² ( a /1 au) −3/2 , the timescale for a cascade to generate an approximate equilibrium is 100–300 Myr at 45 au and 10–30 Myr at 25 au. Although it is necessary to perform more complete evolutionary calculations of the Kuiper Belt, collisional cascades are a viable model for producing the size distribution of solids that impacted Charon throughout its history.
... We use cold water ice parameters (representing a non-porous material) in the gravity regime, a transient crater depth-todiameter ratio of 0.2, an impact angle of 45°, and the formulation for the final-to-transient complex crater conversion derived from crater shapes on icy satellites (66). This method is described in detail in previous papers (35,67). We use an average impactor velocity (U) of 2 km s −1 for Charon and 2.2 km s −1 for Pluto (both equivalent to a velocity at infinity of 1.9 km s −1 for the system). ...
Impact craters on Pluto and Charon
Collisions between Solar System bodies produce impact craters on large objects at a rate that depends on the population of impacting small bodies. Singer et al. examined impact craters on Pluto and its moon Charon. Some regions have had their impact craters erased by recent geological processes, but others appear to record 4 billion years of impacts. Because Pluto and Charon are located in the Kuiper belt, the distribution of crater sizes reflects the size distribution of impacting Kuiper belt objects (KBOs). The authors found fewer small KBOs than predicted by models of collision equilibrium, implying that some of the KBO population has been preserved since the formation of the Solar System.
Science , this issue p. 955
... These hypotheses, borrowed from the Titan literature, view the N 2 as being derived from the bulk planetary inventory. A different approach is to consider exogenous mechanisms of bringing N 2 to the surface of Pluto (e.g., cometary impacts; Singer & Stern, 2015). Beyond an intrinsic interest in the source of N 2 , insights into the origin and evolution of Pluto and the solar system as a whole can be elucidated by addressing the issue of the origin of N 2 on Pluto (Lunine, 1993a). ...
... For P atm ≈ 12 μbar (~1.2 Pa; Hinson et al., 2017), the mass of the atmosphere is ~3.5×10 13 kg. This is consistent with earlier estimates that were made using Earth-based observations (e.g., ~3×10 13 kg; Singer & Stern, 2015). The calculated mass can be assumed to be essentially identical to the mass of N 2 in Pluto's atmosphere as the near-surface atmosphere is >99% N 2 by volume (Young et al., 2018). ...
... The third scenario assumes that effectively all of the accreted CO was destroyed under alkaline conditions, and Pluto's present CO is actually not primordial but was delivered by comets. Singer & Stern (2015) used the impact flux model of Bierhaus & Dones (2015), and estimated that ~3×10 17 kg of cometary materials have been delivered to Pluto over the past 4 billion years. If a typical comet is assumed to be composed of ~50 wt. ...
The presence of N2 in the surface environment of Pluto is critical in creating Pluto's richness of features and processes. Here, we propose that the nitrogen atoms in the N2 observed on Pluto were accreted in that chemical form during the formation of Pluto. We use New Horizons data and models to estimate the amounts of N2 in the following exterior reservoirs: atmosphere, escape, photochemistry, and surface. The total exterior inventory is deduced to be dominated by a glacial sheet of N2-rich ices at Sputnik Planitia, or by atmospheric escape if past rates of escape were much faster than at present. Pluto's atmosphere is a negligible reservoir of N2, and photochemical destruction of N2 may also be of little consequence. Estimates are made of the amount of N2 accreted by Pluto based on cometary and solar compositions. It is found that the cometary model can account for the amount of N2 in Sputnik Planitia, while the solar model can provide a large initial inventory of N2 that would make prodigious atmospheric escape possible. These consistencies can be considered preliminary evidence in support of a primordial origin of Pluto's N2. However, both models predict accreted ratios of CO/N2 that are much higher than that in Pluto's atmosphere. Possible processes to explain "missing CO" that are given quantitative support here are fractional crystallization from the atmosphere resulting in CO burial at the surface, and aqueous destruction reactions of CO subject to metastable thermodynamic equilibrium in the subsurface. The plausibility of primordial N2 as the primary source of Pluto's nitrogen (vs. NH3 or organic N) can be tested more rigorously using future constraints on the 14N/15N ratio in N2 and the 36Ar/N2 ratio.
... It could also conceivably be a source region connected to the deep interior, or it could be a major sink for volatiles released planetwide, or both. Whether deep or surficial processes dominate is currently unclear, but the actual processes involved must be aad1815-4 16 (20). ...
The Pluto system was recently explored by NASA’s New Horizons spacecraft, making closest approach on 14 July 2015. Pluto’s
surface displays diverse landforms, terrain ages, albedos, colors, and composition gradients. Evidence is found for a water-ice
crust, geologically young surface units, surface ice convection, wind streaks, volatile transport, and glacial flow. Pluto’s
atmosphere is highly extended, with trace hydrocarbons, a global haze layer, and a surface pressure near 10 microbars. Pluto’s
diverse surface geology and long-term activity raise fundamental questions about how small planets remain active many billions
of years after formation. Pluto’s large moon Charon displays tectonics and evidence for a heterogeneous crustal composition;
its north pole displays puzzling dark terrain. Small satellites Hydra and Nix have higher albedos than expected.
This thesis is devoted to the experimental and theoretical investigations of four instabilitiesassociated with the emergence of regular patterns over erodible/flexible substrates, andrelated to hydrodynamics over a modulated relief.First, the instability of a flexible sheet clamped at both ends and submitted to a permanentwind is investigated. The flat sheet solution is unstable towards propagative waves, forstrong enough wind. We experimentally study the selection of frequency and wavenumberas a function of the wind velocity. These quantities obey simple scaling laws derived froma linear stability analysis of the problem. This phenomenon may be applied for energyharvesting.Second, an explanation is proposed for the giant ripples observed by spacecraft Rosettaat the surface of the comet 67P. We show that the outgassing flow across a porous surfacegranular layer and the strong pressure gradient associated with the day-night alternanceare responsible for thermal superficial winds. We show that these unexpected patterns areanalogous to ripples emerging on granular beds submitted to viscous shear flows. Linearstability analysis of the problem quantitatively predicts the emergence of bedforms at theobserved wavelength and their propagation. This description provides a reliable tool topredict the erosion and accretion processes controlling the evolution of small solar systembodies.Third, we propose a model for rhythmic, dune-like patterns observed on SputnikPlanum of Pluto. Their emergence and evolution are related to the differential condensation/sublimation of nitrogen ice. We show that the temperature and pressure in Pluto’satmosphere are almost homogeneous and steady, and that heat flux from the atmospheredue to convection and turbulent mixing is responsible for the emergence of these sublimationpatterns, in contrast to the penitentes instability due to solar radiation.Last, we report an analytical model for the aeolian ripple instability by considering theresonant grain trajectories over a modulated sand bed, taking the collective effect in thetransport layer into account. The model is tested against existing numerical simulationsthat match experimental observations.
