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Pandora (moon)

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Pandora
PIA21055 - Pandora Up Close.jpg
View of Pandora's western hemisphere.[a]
Discovery
Discovered by Collins, Voyager 1
Discovery date October, 1980
Orbital characteristics[1]
Epoch December 31, 2003 (JD 2453005.5)
141720±10 km
Eccentricity 0.0042
0.628504213 d
Inclination 0.050°±0.004° to Saturn's equator
Satellite of Saturn
Physical characteristics
Dimensions 104 × 81 × 64 km [2]
Mean radius
40.7±1.5 km [2]
Volume ≈ 280000 km3
Mass (1.371±0.019)×1017 kg[2]
Mean density
0.49±0.06 g/cm3[2]
0.0026–0.0060 m/s2[2]
≈ 0.019 km/s
synchronous
zero
Albedo 0.6
Temperature ≈ 78 K

Pandora (/pænˈdɔərə/ pan-DOHR; Greek: Πανδώρα) 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.[3] In late 1985 it was officially named after Pandora from Greek mythology.[4] It is also designated as Saturn XVII.[5]

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.[6][7] 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.[8]

The orbit of Pandora appears to be chaotic, as a consequence of a series of four 118:121 mean-motion resonances with Prometheus.[9] The most appreciable changes in their orbits occur approximately every 6.2 years,[1] 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.[1]

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

Gallery

References

Notes
  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.
Citations
  1. ^ a b c Spitale Jacobson et al. 2006.
  2. ^ a b c d e Thomas 2010.
  3. ^ IAUC 3532.
  4. ^ IAUC 4157.
  5. ^ USGS: Planet and Satellite Names and Discoverers.
  6. ^ Lakdawalla, E. (2014-07-05). "On the masses and motions of mini-moons: Pandora's not a "shepherd," but Prometheus still is". Planetary Society. Retrieved 2015-04-17. 
  7. ^ 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. Bibcode:2014Icar..232..157C. ISSN 0019-1035. doi:10.1016/j.icarus.2013.12.027. 
  8. ^ Solar System, NASA: Pandora.
  9. ^ Renner et al. 2005.
Sources
  • Marsden, Brian G. (October 31, 1980). "Satellites of Saturn" (discovery). IAU Circular. 3532. Retrieved 2011-12-29. 
  • Marsden, Brian G. (January 3, 1986). "Satellites of Saturn and Pluto" (naming the moon). IAU Circular. 4157. 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. Bibcode:2005Icar..174..230R. doi:10.1016/j.icarus.2004.09.005. 
  • "Saturn: Moons: Pandora". Solar System Exploration: Planets. NASA. 4 Apr 2011. Retrieved 2011-12-29. 
  • 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" (PDF). The Astronomical Journal. 132 (2): 692–710. Bibcode:2006AJ....132..692S. doi:10.1086/505206. 
  • Thomas, P. C. (July 2010). "Sizes, shapes, and derived properties of the saturnian satellites after the Cassini nominal mission" (PDF). Icarus. 208 (1): 395–401. Bibcode:2010Icar..208..395T. doi:10.1016/j.icarus.2010.01.025. 
  • USGS/IAU (July 21, 2006). "Planet and Satellite Names and Discoverers". Gazetteer of Planetary Nomenclature. USGS Astrogeology. Retrieved 2011-12-29. 

External links

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