ESA Science & Technology04-Jul-2005 14:23:46
 

Saturn's Moons

Rhea

V - Discovered by Cassini (1672)

Physical Parameters

Orbital Parameters

Radius (km)

764

Radius (km)

527 040

Mean Density (kgm-3)

1240

Period

4d 12h 26m

Mass (kg)

2.3 x 1021

Velocity (kms-1)

8.48

Magnitude (V0)

9.7

Rotational Period

4d 12h 26m

Escape Velocty (kms-1)

0.659

Eccentricity

0.001

Mean Surface Albedo

0.6

Inclination ( °)

0.35

Knowledge before Cassini-Huygens

Rhea is Saturn's second largest moon and shows little evidence for activity. The surface is saturated with craters and looks somewhat similar to our Moon. The surface is though to be an ancient one due to the density of craters.

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

20 July 2004

Cassini Instrument: Imaging Science Subsystem

Date: 02 July 2004

Distance: 990 000 km

Scale: 6 km per pixel

Phase Angle: 109 °

Notes: Narrow angle camera, visible light


20 September 2004

Cassini Instrument: Imaging Science Subsystem

Dates: 15 July, 20 July and 16 August 2004

Distances: 5.1, 5.9 and 8.5 million km

Scales: 31, 35 and 51 km per pixel

Phase Angle: 90, 91 and 86 °

Images Notes: Narrow angle, visible light. The left image was magnified x2, and the other two images x4. The right image  is contrast enhanced.


22 November 2004

Cassini Instrument: Imaging Science Subsystem

Date: 24 October 2004

Distance: 1.7 million km

Scale: ~10 km per pixel

Phase Angle: 40 °  

Image Notes: Narrow angle, visible light, bright, rayed crater near eastern limb


1 February 2005

Cassini Instrument: Imaging Science Subsystem

Date: 16 January 2005

Distance: ~500 000 km

Scale: ~3 km per pixel

Phase Angle: 35 °

Image Notes: Narrow angle, visible light, magnified x2, contrast enhanced, image been rotated so that north is uppermost.

This view of the trailing hemisphere of Saturn's moon Rhea shows the region's bright wispy markings, but also the moon's craters in great detail. Of particular interest is the distribution and orientation of the many craters with rough polygonal rims.



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