Pandora (moon)

This article is about the moon of Saturn. For the fictional moon in the Avatar franchise, see Fictional universe of Avatar. For the asteroid, see 55 Pandora.
Pandora
View of Pandora's western hemisphere.[a]
Discovery
Discovered byStewart A. Collins
D. Carlson
Voyager 1
Discovery dateOctober, 1980
Designations
Designation
Saturn XVII
Pronunciation/pænˈdɔːrə/
Named after
Πανδώρα Pandōra
AdjectivesPandoran[1]
Orbital characteristics [2]
Epoch December 31, 2003 (JD 2453005.5)
141720±10 km
Eccentricity0.0042
0.628504213 d
Inclination0.050°±0.004° to Saturn's equator
Satellite ofSaturn
GroupPossible outer shepherd moon of the F Ring
Physical characteristics
Dimensions103.0 × 79.0 × 63.0 km
(± 0.6 × 0.6 × 0.4 km)[3]: 2 
80.0±0.6 km[3]: 2 
Volume268990±860 km3[4]: 4 
Mass(1.357±0.002)×1017 kg[b]
Mean density
0.5045±0.0017 g/cm3[4]: 4 
0.0022–0.0061 m/s2[3]: 3 
0.019 km/s at longest axis
to 0.024 km/s at poles
synchronous
zero
Albedo0.6
Temperature≈ 78 K

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 as 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 the 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. However, there is much uncertainty in these values, so this remains to be confirmed.

[edit]
  • View of the moon, taken during Cassini's September 2005 flyby.
    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.
    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.
    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).
    Voyager 2 image of Pandora (August 1981).

References

[edit]
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Notes

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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.
  2. ^ 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

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  1. ^ Robert Kolvoord (1990) Saturn's F ring: imaging and simulation, p. 104
  2. ^ a b c Spitale Jacobson et al. 2006.
  3. ^ a b c Thomas & Helfenstein 2020.
  4. ^ a b c Lainey et al. 2023.
  5. ^ IAUC 3532.
  6. ^ IAUC 4157.
  7. ^ USGS: Planet and Satellite Names and Discoverers.
  8. ^ 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.
  9. ^ 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. doi:10.1016/j.icarus.2013.12.027. ISSN 0019-1035.
  10. ^ Solar System, NASA: Pandora.
  11. ^ Renner et al. 2005.

Sources

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[edit]
Wikimedia Commons has media related to Pandora (moon).
  • Pandora at NASA's Solar System Exploration
  • Pandora at The Planetary Society
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