ESA Science & Technology04-Jul-2005 14:22:33
 

Saturn's Moons

Enceladus

II - Discovered by Herschel (1789)

Physical Parameters

Orbital Parameters

Radius (km)

250

Radius (km)

238 020

Mean Density (kgm-3)

1000

Period

1d 08h 53m

Mass (kg)

6.5 x 1019

Velocity (kms-1)

12.64

Magnitude (V0)

11.8

Rotational Period

1d 08h 53m

Escape Velocty (kms-1)

0.212

Eccentricity

0.0045

Mean Surface Albedo

1.0

Inclination ( °)

0.02

Knowledge before Cassini-Huygens

Enceladus has a relatively young surface showing a wide range of features suggesting an active geological history. Some surface regions are devoid of craters - having been covered by ice flows or reformed by geological processes. These smoother regions show no evidence for cratering suggesting that they have formed within the last 100 million years.

These differences suggest that there is a plastic, or liquid layer around 15 km below the crust. No volcanic features have been seen on the surface, but current theories suggest material from Enceladus is being used to refresh Saturn's E ring.

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

23 July 2004

Cassini Instrument: Imaging Science Subsystem

Date: 03 July 2004

Distance: 1.6 million km

Scale: 10 km per pixel

Phase Angle: 103 °

Image Notes: Narrow angle camera, visible light


20 November 2004

Cassini Instrument: Imaging Science Subsystem

Date: 27 October 2004

Distance: 766 000 km

Scale: 4.6 km per pixel

Phase Angle: 34 °

Image Notes: Narrow angle, visible light

This Cassini view of Enceladus hints at the curvilinear, groove-like features that crisscross the moon's surface, as seen in images from NASA's Voyager spacecraft. The image shows the trailing hemisphere of Enceladus, which is the side opposite the moon's direction of motion in its orbit.


20 January 2005

Cassini Instrument: Imaging Science Subsystem

Date: 15 January 2005

Distance: ~367 000 km

Scale: ~2 km per pixel

Phase Angle: 74 °

Image Notes: Narrow angle camera, filtered in infrared and polarized light, magnified x2 and contrast enhanced

This image of Enceladus shows a region containing bizarre, wrinkled terrain, largely free of craters, indicating that this region is geologically young. This view shows primarily the leading hemisphere of Enceladus. The image has been rotated so that north on Enceladus is up.


18 February 2005

Cassini Instrument: Imaging Science Subsystem

Date: 17 February 2005

Distance: 10 750 km

Scale: 60 m per pixel

Phase Angle: 32 °

Image Notes:  Narrow angle camera,  visible light, contrast-enhanced. Sunlight illuminates the scene from the bottom.

The topographic relief in this view is only about one kilometre, which is quite low for a small, low-gravity satellite. However, this is consistent with other evidence that points to interior melting and resurfacing in Enceladus' history.

Date: 17 February 2005

Distance: between 26  140 and 17  434 km

Scale: 150 m  per pixel (left) 105 m  per pixel (right)

Phase Angle: 27 to 29 °

Image Notes: Narrow angle camera,  visible light, contrast-enhanced.

The mosaic covers longitudes from about 254 west to 296 west and latitudes from 60 south to the equator, and shows many styles of fracturing.



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