J/AJ/162/207 Dark-floored pits in Sputnik Planitia on Pluto (Stern+, 2021)
New investigations of dark-floored pits in the volatile ice of Sputnik Planitia
on Pluto.
Stern S., Keeney B., Hoover R., Protopapa S., White O., Grundy W.,
Cruikshank D.P., (the New Horizons Team)
<Astron. J., 162, 207-207 (2021)>
=2021AJ....162..207S 2021AJ....162..207S (SIMBAD/NED BibCode)
ADC_Keywords: Solar system; Minor planets; Optical
Keywords: Pluto; Atmospheric effects; Surface processes; Surface ices
Abstract:
Sputnik Planitia, Pluto's gigantic, volatile ice glacier, hosts
numerous scientific mysteries, including the presence of thousands of
elongated pit structures. We examine various attributes of these pit
structures in New Horizons data sets, revealing their length, aspect
ratio, and orientation properties; we also study their reflectivities,
colors, and compositions, and compare these attributes to some other
relevant regions on Pluto. We then comment on origin mechanisms of the
pits and also the fate of the missing volatiles represented by the
pits on Sputnik Planitia. From a sample of 317 pits, we find typical
length/width ratios of 2-4, with their major axis preferentially
oriented approximately north-south. We also find that the floors of
large pits in our sample have similar single-scattering albedos and
colors to dark material on crater rims and floors (i.e., possible
subsurface windows) in Burney basin. We also find that the base of the
three pits in our sample, large enough to study with LEISA IR
spectroscopy, display both CH4 and N2 absorption features, as do
the dark regions in crater windows in Burney basin. Evidence for a
sublimation erosion origin for the pits is supported over both the
explosion/ejecta venting and structural collapse alternatives.
Finally, we find that the mass lost by the pits on Sputnik Planitia
most likely lies condensed elsewhere, on Pluto's surface, relocated
there by volatile transport as opposed to removal by escape to space
or photochemical conversion.
Description:
For this study, we catalogued 317 dark-floored pits observed in the
highest resolution (80-240m/pixel) New Horizons Long Range
Reconnaissance Imager (LORRI) imaging of SP. All of these pits were
selected to have lengths >1km and widths >350m, and all are resolved
in the lowest-resolution LORRI imaging used (240m/pixel), which covers
the entire study area.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 51 317 Catalog of pit properties
table4.dat 43 205 LORRI Albedos of pits
table5.dat 78 56 Properties of burney comparison regions
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See also:
J/A+A/553/A14 : Pluto's observations between 1997 and 2010 (Beauvalet+, 2013)
J/A+A/570/A86 : Pluto astrometry 19yrs observations (Benedetti-Rossi+, 2014)
J/AJ/149/22 : Astrometry of Pluto from 1930-1951 observations (Buie+, 2015)
J/AJ/152/80 : Astrometry of Pluto and trans-Neptunian objects (Holman+, 2016)
J/AJ/159/74 : Disk-resolved photometric properties Pluto (Protopapa+, 2020)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- PitID [0/331] Pit identifier
5- 14 F10.6 deg Lat [-15.4/20] Latitude on Pluto
16- 25 F10.6 deg Lon [152/193] Longitude on Pluto
27- 32 F6.3 km2 Area [0.41/60.1] Area
34- 39 F6.3 km Length [1.07/16.2] Length
41- 45 F5.3 km Width [0.35/9.82] Width
47- 51 F5.1 deg Azimuth [-87/83.7] Azimuth (1)
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Note (1): Azimuth is the orientation of each pit's major axis, measured
counterclockwise from north.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- ID [0/311] Unshadowed region ID
5- 7 I3 --- PitID [0/331] Pit identifier (1)
9- 14 F6.3 km2 Area [0.05/14.7] Area
16- 20 F5.3 --- omega [0.43/0.97] Mean LORRI Albedo
22- 26 F5.3 --- e_omega [0.01/0.2] Std. Deviation of omega
28- 31 I4 --- n_omega [10/2293] number of unshadowed pixels
33- 37 F5.3 --- b_omega [0.05/0.9] Minimum Albedo
39- 43 F5.3 --- B_omega [0.73/1] Maximum Albedo
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Note (1): PitID lists the corresponding ID from Table 2; shadowing can split
a single pit into multiple unshadowed regions.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- ID [0/55] Burney Comparison Region identifier
4- 12 F9.6 deg Lat [40.8/52.2] Latitude on Pluto
14- 23 F10.6 deg Lon [126/142] Longitude on Pluto
25- 30 F6.3 km2 Area [0.58/18.2] Area
32- 37 F6.3 km Length [1.45/12.3] Length
39- 43 F5.3 km Width [0.55/8] Width
45- 49 F5.1 deg Azimuth [-90/89] Azimuth (1)
51- 55 F5.3 --- omega [0.53/0.92] Mean LORRI Albedo
57- 61 F5.3 --- e_omega [0.03/0.1] Std. Deviation of omega
63- 66 I4 --- n_omega [92/3081] number of unshadowed pixels
68- 72 F5.3 --- b_omega [0.37/0.82] Minimum Albedo
74- 78 F5.3 --- B_omega [0.68/1] Maximum Albedo
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Note (1): Azimuth is the orientation of each region's major axis, measured
counterclockwise from north.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 12-Jan-2022