Pandora (Moon)

Pandora
	View of Pandora's western hemisphere.
Discovery
Discovered by	Stewart A. Collins; D. Carlson; Voyager 1
Discovery date	October, 1980
Designations
Designation	Saturn XVII
Pronunciation	/pænˈdɔːrə/
Named after	Πανδώρα Pandōra
Adjectives	Pandoran
Orbital characteristics
	Epoch December 31, 2003 (JD 2453005.5)
Semi-major axis	141720±10 km
Eccentricity	0.0042
Orbital period	0.628504213 d
Inclination	0.050°±0.004° to Saturn's equator
Satellite of	Saturn
Group	Possible outer shepherd moon of the F Ring
Physical characteristics
Dimensions	103.0 × 79.0 × 63.0 km; (± 0.6 × 0.6 × 0.4 km)
Mean diameter	80.0±0.6 km
Volume	268990±860 km3
Mass	(1.357±0.002)×1017 kg
Mean density	0.5045±0.0017 g/cm3
surface gravity	0.0022–0.0061 m/s2
escape velocity	0.019 km/s at longest axis; to 0.024 km/s at poles
Rotation period	synchronous
Axial tilt	zero
Albedo	0.6
Physics	≈ 78 K

Short description: Moon of Saturn

Pandora is an inner satellite of Saturn. It was discovered in 1980 from photos taken by the Voyager 1 probe, and was provisionally designated S/1980 S 26.^[5] In late 1985 it was officially named after Pandora from Greek mythology.^[6] It is also designated Saturn XVII.^[7]

Pandora was thought to be an outer shepherd satellite of the F Ring. However, recent studies indicate that it does not play such a role, and that only Prometheus, the inner shepherd, contributes to the confinement of the narrow ring.^[8]^[9] It is more heavily cratered than nearby Prometheus, and has at least two large craters 30 kilometres (19 mi) in diameter. The majority of craters on Pandora are shallow as a result of being filled with debris. Ridges and grooves are also present on moon's surface.^[10]

The orbit of Pandora appears to be chaotic, as a consequence of a series of four 118:121 mean-motion resonances with Prometheus.^[11] The most appreciable changes in their orbits occur approximately every 6.2 years,^[2] when the periapsis of Pandora lines up with the apoapsis of Prometheus and the moons approach to within about 1,400 kilometres (870 mi). Pandora also has a 3:2 mean-motion resonance with Mimas.^[2]

From its very low density and relatively high albedo, it seems likely that Pandora is a very porous icy body. There is much uncertainty in these values, however, so this remains to be confirmed.

Gallery

View of the moon, taken during Cassini's September 2005 flyby.
Pandora as seen from the Cassini probe in 2005; the rings of Saturn are in the background.
Cassini captured this close view of Saturn's moon Pandora during the spacecraft's flyby on June 3, 2010.
Voyager 2 image of Pandora (August 1981).

References

Notes

↑ This view was taken by Cassini, during the spacecraft's close flyby on December 18, 2016. The image was taken from a distance of 40,500 kilometres (25,200 miles); the closest approach by the spacecraft during its 14-year tenure in the Saturn system.
↑ Calculated from the standard gravitational parameter GM = (9.058±0.011)×10⁻³ km³·s^–2 given by Lainey et al. (2023), divided by the gravitational constant G = 6.6743×10⁻² km³·kg^–1·s^–2.^[4]

Citations

↑ Robert Kolvoord (1990) Saturn's F ring: imaging and simulation, p. 104
↑ ^2.0 ^2.1 ^2.2 Spitale Jacobson et al. 2006.
↑ ^3.0 ^3.1 ^3.2 Thomas & Helfenstein 2020.
↑ ^4.0 ^4.1 ^4.2 Lainey et al. 2023.
↑ IAUC 3532.
↑ IAUC 4157.
↑ USGS: Planet and Satellite Names and Discoverers.
↑ "On the masses and motions of mini-moons: Pandora's not a "shepherd," but Prometheus still is". Planetary Society. 2014-07-05. http://www.planetary.org/blogs/emily-lakdawalla/2014/07010001-ringmoons-shepherds.html.
↑ Cuzzi, J. N.; Whizin, A. D.; Hogan, R. C.; Dobrovolskis, A. R.; Dones, L.; Showalter, M. R.; Colwell, J. E.; Scargle, J. D. (April 2014). "Saturn's F Ring core: Calm in the midst of chaos". Icarus 232: 157–175. doi:10.1016/j.icarus.2013.12.027. ISSN 0019-1035. Bibcode: 2014Icar..232..157C.
↑ Solar System, NASA: Pandora.
↑ Renner et al. 2005.

Sources

Marsden, Brian G. (October 31, 1980). "Satellites of Saturn" (discovery). IAU Circular 3532. http://www.cbat.eps.harvard.edu/iauc/03500/03532.html. Retrieved 2011-12-29.
Marsden, Brian G. (January 3, 1986). "Satellites of Saturn and Pluto" (naming the moon). IAU Circular 4157. http://www.cbat.eps.harvard.edu/iauc/04100/04157.html. Retrieved 2011-12-29.
Renner, Stéfan F.; Sicardy, Bruno; French, Richard G. (March 2005). "Prometheus and Pandora: Masses and orbital positions during the Cassini tour". Icarus 174 (1): 230–240. doi:10.1016/j.icarus.2004.09.005. Bibcode: 2005Icar..174..230R.
"Saturn: Moons: Pandora". Solar System Exploration: Planets. NASA. 4 Apr 2011. http://solarsystem.nasa.gov/planets/profile.cfm?Object=Sat_Pandora.
Spitale, J. N.; Jacobson, R. A.; Porco, C. C.; Owen, W. M. Jr. (2006). "The orbits of Saturn's small satellites derived from combined historic and Cassini imaging observations". The Astronomical Journal 132 (2): 692–710. doi:10.1086/505206. Bibcode: 2006AJ....132..692S.
Thomas, P. C. (July 2010). "Sizes, shapes, and derived properties of the saturnian satellites after the Cassini nominal mission". Icarus 208 (1): 395–401. doi:10.1016/j.icarus.2010.01.025. Bibcode: 2010Icar..208..395T. http://www.ciclops.org/media/sp/2011/6794_16344_0.pdf.
USGS/IAU (July 21, 2006). "Planet and Satellite Names and Discoverers". Gazetteer of Planetary Nomenclature. USGS Astrogeology. http://planetarynames.wr.usgs.gov/Page/Planets#SaturnianSystem.
Thomas, P. C.; Helfenstein, P. (July 2020). "The small inner satellites of Saturn: Shapes, structures and some implications". Icarus 344: 20. doi:10.1016/j.icarus.2019.06.016. 113355. Bibcode: 2020Icar..34413355T.
Lainey, V.; Rambaux, N.; Cooper, N.; Dahoumane, R.; Zhang, Q. (February 2023). "Characterising the interior of five inner Saturnian moons using Cassini ISS data". Astronomy & Astrophysics 670: 6. doi:10.1051/0004-6361/202244757. L25. Bibcode: 2023A&A...670L..25L.

External links

Pandora at NASA's Solar System Exploration
Pandora at The Planetary Society

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[1] This view was taken by Cassini, during the spacecraft's close flyby on December 18, 2016. The image was taken from a distance of 40,500 kilometres (25,200 miles); the closest approach by the spacecraft during its 14-year tenure in the Saturn system.

[6] Calculated from the standard gravitational parameter GM = (9.058±0.011)×10⁻³ km³·s^–2 given by Lainey et al. (2023), divided by the gravitational constant G = 6.6743×10⁻² km³·kg^–1·s^–2.^[4]

[2] Robert Kolvoord (1990) Saturn's F ring: imaging and simulation, p. 104

[FOOTNOTESpitale_Jacobson_et_al.2006-3] 2.0 ^2.1 ^2.2 Spitale Jacobson et al. 2006.

[FOOTNOTEThomas_&_Helfenstein2020-4] 3.0 ^3.1 ^3.2 Thomas & Helfenstein 2020.

[FOOTNOTELainey_et_al.2023-5] 4.0 ^4.1 ^4.2 Lainey et al. 2023.

[FOOTNOTEIAUC_3532-7] IAUC 3532.

[FOOTNOTEIAUC_4157-8] IAUC 4157.

[FOOTNOTEUSGS:_Planet_and_Satellite_Names_and_Discoverers-9] USGS: Planet and Satellite Names and Discoverers.

[LakdawallaE2014-10] "On the masses and motions of mini-moons: Pandora's not a "shepherd," but Prometheus still is". Planetary Society. 2014-07-05. http://www.planetary.org/blogs/emily-lakdawalla/2014/07010001-ringmoons-shepherds.html.

[Cuzzi2014-11] Cuzzi, J. N.; Whizin, A. D.; Hogan, R. C.; Dobrovolskis, A. R.; Dones, L.; Showalter, M. R.; Colwell, J. E.; Scargle, J. D. (April 2014). "Saturn's F Ring core: Calm in the midst of chaos". Icarus 232: 157–175. doi:10.1016/j.icarus.2013.12.027. ISSN 0019-1035. Bibcode: 2014Icar..232..157C.

[FOOTNOTESolar_System,_NASA:_Pandora-12] Solar System, NASA: Pandora.

[FOOTNOTERenner_et_al._2005-13] Renner et al. 2005.

v t e Moons of Saturn
Listed in approximately increasing distance from Saturn.
Ring shepherds	S/2009 S 1 Ring moonlets Pan Daphnis Atlas Prometheus Pandora
Co-orbitals	Epimetheus Janus
G Ring	Aegaeon
Alkyonides	Methone Anthe Pallene
Inner large (with trojans)	Mimas Enceladus Tethys Telesto Calypso Dione Helene Polydeuces
Outer large	Rhea Titan Hyperion Iapetus
Inuit group	Kiviuq Ijiraq Paaliaq S/2004 S 29 S/2004 S 31 Siarnaq Tarqeq
Norse group	Phoebe Skathi S/2004 S 37 S/2007 S 2 Skoll S/2004 S 13(?) Greip Hyrrokkin Jarnsaxa Mundilfari S/2006 S 1 S/2004 S 17(?) Bergelmir Narvi S/2004 S 20 Suttungr Hati S/2004 S 12(?) S/2004 S 27 Farbauti Thrymr S/2004 S 30 Aegir S/2007 S 3(?) Bestla S/2004 S 7(?) S/2004 S 22(?) S/2004 S 23(?) S/2004 S 25(?) S/2004 S 32(?) S/2006 S 3 S/2004 S 38(?) Fenrir S/2004 S 28(?) Surtur Kari S/2004 S 35(?) Ymir S/2004 S 21(?) Loge S/2004 S 36(?) S/2004 S 39(?) S/2004 S 33(?) S/2004 S 34(?) Fornjot S/2004 S 26(?)
Gallic group	Albiorix Bebhionn Erriapus Tarvos
Prograde outer satellites	S/2004 S 24
Rings of Saturn Cassini–Huygens Themis Chiron S/2004 S 6 S/2004 S 4 S/2004 S 3 In fiction

v t e Saturn
Outline of Saturn
Geography	Dragon Storm Great White Spot Hexagon Magnetosphere Rings
Moons	S/2009 S 1 Ring moonlets Pan Daphnis Atlas Prometheus S/2004 S 6 S/2004 S 4 S/2004 S 3 Pandora Epimetheus Janus Aegaeon Mimas Methone Anthe Pallene Enceladus Tethys Telesto Calypso Dione Helene Polydeuces Rhea Titan Hyperion Iapetus Kiviuq Ijiraq Phoebe Paaliaq Skathi S/2004 S 37 Albiorix S/2007 S 2 S/2004 S 29 Bebhionn Erriapus Skoll S/2004 S 31 Siarnaq Tarqeq S/2004 S 13 Greip Hyrrokkin Jarnsaxa Tarvos Mundilfari S/2006 S 1 S/2004 S 17 Bergelmir Narvi S/2004 S 20 Suttungr Hati S/2004 S 12 S/2004 S 27 Farbauti Thrymr S/2004 S 30 Aegir S/2007 S 3 Bestla S/2004 S 7 S/2004 S 22 S/2004 S 23 S/2004 S 25 S/2004 S 32 S/2006 S 3 S/2004 S 38 Fenrir S/2004 S 28 Surtur Kari S/2004 S 35 Ymir S/2004 S 21 S/2004 S 24 Loge S/2004 S 36 S/2004 S 39 S/2004 S 33 S/2004 S 34 Fornjot S/2004 S 26
Astronomy	Delta Octantis Saturn-crossing minor planets
Exploration	Cassini–Huygens (Huygens) timeline retirement Pioneer 11 Voyager program Voyager 1 Voyager 2
Related	Fiction Moons The Day the Earth Smiled In Saturn's Rings (2018 documentary)

Discovery
View of Pandora's western hemisphere.^{[lower-alpha 1]}
Discovered by	Stewart A. Collins D. Carlson Voyager 1
Discovery date	October, 1980
Designations
Designation	Saturn XVII
Pronunciation	/pænˈdɔːrə/
Named after	Πανδώρα Pandōra
Adjectives	Pandoran^[1]
Orbital characteristics ^[2]
Epoch December 31, 2003 (JD 2453005.5)
Semi-major axis	141720±10 km
Eccentricity	0.0042
Orbital period	0.628504213 d
Inclination	0.050°±0.004° to Saturn's equator
Satellite of	Saturn
Group	Possible outer shepherd moon of the F Ring
Physical characteristics
Dimensions	103.0 × 79.0 × 63.0 km (± 0.6 × 0.6 × 0.4 km)^[3]^(p2)
Mean diameter	80.0±0.6 km^[3]^(p2)
Volume	268990±860 km³^[4]^(p4)
Mass	(1.357±0.002)×10¹⁷ kg^{[lower-alpha 2]}
Mean density	0.5045±0.0017 g/cm³^[4]^(p4)
surface gravity	0.0022–0.0061 m/s²^[3]^(p3)
escape velocity	0.019 km/s at longest axis to 0.024 km/s at poles
Rotation period	synchronous
Axial tilt	zero
Albedo	0.6
Physics	≈ 78 K