ESA Science & Technology04-Jul-2005 14:24:07

Saturn's Moons

Hyperion

VII - Discovered by Bond, Bond & Lassel (1848)

Physical Parameters

Orbital Parameters

Radius (km)

140

Radius (km)

1 481 100

Mean Density (kgm-3)

1500

Period

21d 6h 38m

Mass (kg)

0.2 x 1020

Velocity (kms-1)

5.07

Magnitude (V0)

14.4

Rotational Period

chaotic

Escape Velocty (kms-1)

0.107

Eccentricity

0.104

Mean Surface Albedo

0.3

Inclination ( )

0.43

Knowledge before Cassini-Huygens

Hyperion is one of Saturn's smaller satellites and its elliptical orbit lies between that of Titan and Iapetus. Hyperion's low density indicates that the satellite is mainly composed of water-ice with a small amount of rocky material. The surface is covered with a darker material causing Hyperion to have a lower albedo compared to other icy moons.

Hyperion's shape is very irregular and it has been suggested that the satellite once was part of a larger object that was fractured by an impact in the distant past. Hyperion's surface also shows signs of heavy cratering with the largest crater approximately 120 km in diameter.

The orientation of Hyperion's axis of rotation is chaotic and unpredictable. The cause for the chaotic rotation could be due to the proximity of the large moon Titan, the ellipticity of Hyperions orbit and the 3:4 resonance between the orbital period of Titan and Hyperion.

*Note: in the following section all images courtesy NASA/JPL/Space Science Institute unless stated otherwise.

12 August 2004

Cassini Instrument: Imaging Science Subsystem

Date: 02 July 2004

Distance: 6.7 million km

Scale: 40 km per pixel

Phase Angle: 95

Image Notes: Narrow angle, visible light, magnified x4.


28 September 2004

Cassini Instrument: Imaging Science Subsystem

Date: 12 September 2004

Distance: 8.8 million km

Scale: 53 km per pixel

Phase Angle: 90

Image Notes: Narrow angle, visible light, magnified x4


24 November 2004

Cassini Instrument: Imaging Science Subsystem

Date: 20 October 2004

Distance: 2.2 million km

Scale: 13 km per pixel

Phase Angle: 50

Image Notes: Narrow angle, visible light


18 March 2005

Cassini Instrument: Imaging Science Subsystem

Date: Oct 2004 - Feb 2005

Distance: 1.3 - 1.6 million km

Scale: 8 - 10 km per pixel

Phase Angle: 42 - 66

Image Notes: Narrow angle, visible light, magnified x2, contrast enhanced



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