SP-474 Voyager 1 and 2 Atlas of Six Saturnian Satellites

 

PART 6

[121] Iapetus

 

Diameter

1488km (900) miles)

Density

1.2

Albedo

0.6

Bright side

0.5

Dark side

0.05

Distance from Saturn

3 559 400 km (2 211 704 miles)

Orbital period

1901 hr, 49 min, 12 sec

Voyager 1 closest approach

2 470 000 km (1 534 784 miles)

Voyager 1 pictures used in mapping

3

Voyager 2 closest approach

909 070 km (564 870 miles)

Voyager 2 pictures used in mapping

8

One of the unique phenomena discovered on Iapetus is the extreme diference in albedo between the hemisphere that always faces in the direction of orbital movement (leading hemisphere) and the opposite hemisphere (trailing hemisphere). The leading hemisphere is about the color and brightness of coal, while the trailing hemisphere has the approximate brightness and color of somewhat dirty snow. Because of the extreme differences in brightness, Voyager 1 and 2 were able to resolve data only in the trailing hemisphere. Several theories have been proposed to explain this difference, but no really convincing explanation has been found.

 

[122] Figure 6-1. Resolution of Voyager pictures of Iapetus in terms of aerial coverage.

Figure 6-1. Resolution of Voyager pictures of Iapetus in terms of aerial coverage

[123] Figure 6-2. Index of Voyager 1 and 2 pictures used to compile the maps of Iapetus. Picture numbers indicate the subspacecraft point at the time the pictures are taken. Contour lines indicate the approximate resolution of available images in kilometers per picture element. (See also fig. 6-1).

Figure 6-2. Index of Voyager 1 and 2 pictures used to compile the maps of Iapetus.

[124 - 125] Figure 6-3. Maps of the equatorial region of Iapetus on a Mercator projection (part of map I-1486).

Figure 6-3. Maps of the equatorial region of Iapetus on a Mercator projection (part of map I-1486), part 1.

Figure 6-3. Maps of the equatorial region of Iapetus on a Mercator projection (part of map I-1486), part 2.

[126] Figure 6-4. Map of the north polar regions of Iapetus on a polar stereographic projection (part of map I-1486).

Figure 6-4. Map of the north polar regions of Iapetus on a polar stereographic projection (part of map I-1486).

[127] Figure 6-5. Map of the anti-Saturn-facing hemisphere of Iapetus on a Lambert azimuthal equal-area projection. Nomenclature is not shown, to avoid obscuring detail. Scale 1:10 000 000 (1 mm2 = 100 km2; 1 in2 = ~25 000 mi2).

Figure 6-5. Map of the anti-Saturn-facing hemisphere of Iapetus on a Lambert azimuthal equal-area projection

[128] Figure 6-6. Map of the Saturn-facing hemisphere of Iapetus on a Lambert azimuthal equal-area projection. Nomenclature is not shown, to avoid obscuring detail. Scale 1:10 000 000 (1 mm2 = 100 km2; 1 in2 = ~25 000 mi2).

Figure 6-6. Map of the Saturn-facing hemisphere of Iapetus on a Lambert azimuthal equal-area projection.

[129] Figure 6-7. Picno 0480S1+000. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

Picno

0480S1+000

FDS

34951.56

Range, km

3 221 033

Subspacecraft latitude/longitude, degrees

1/13

Subsolar latitude/longitude, degrees

9/3

Resolution, km/pixel

30

Filter size, pixels

9 x 9

Filter size, km

268

Scale

1:15 000 000

Figure 6-7. Picno 0480S1+000. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

[130] Figure 6-8. Picno 0182S1+001. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

Picno

0182S1+001

FDS

34976.58

Range, km

2 635 830

Subspacecraft latitude/longitude, degrees

17/19

Subsolar latitude/longitude, degrees

9/7

Resolution, km/pixel

24

Filter size, pixels

9 x 9

Filter size, km

219

Scale

1:15 000 000

Figure 6-8. Picno 0182S1+001. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

[131] Figure 6-9. Picno 0110S1+002. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

Picno

0110S1+002

FDS

35005.46

Range, km

2 495 351

Subspacecraft latitude/longitude, degrees

37/44

Subsolar latitude/longitude, degrees

9/12

Resolution, km/pixel

23

Filter size, pixels

9 x 9

Filter size, km

208

Scale

1:15 000 000

Figure 6-9. Picno 0110S1+002. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

[132] Figure 6-10. Picno 1562S2-006. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

Picno

1562S2-006

FDS

43851.39

Range, km

2 226 309

Subspacecraft latitude/longitude, degrees

32/179

Subsolar latitude/longitude, degrees

11/188

Resolution, km/pixel

20

Filter size, pixels

9 x 9

Filter size, km

391

Scale

1:15 000 000

Figure 6-10. Picno 1562S2-006. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

[133] Figure 6-11. Picno 1174S2-005. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

Picno

1174S2-005

FDS

43875.11

Range, km

1 545 842

Subspacecraft latitude/longitude, degrees

42/191

Subsolar latitude/longitude, degrees

11/192

Resolution, km/pixel

14

Filter size, pixels

15 x 15

Filter size, km

214

Scale

1:15 000 000

Figure 6-11. Picno 1174S2-005. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

[134] Figure 5-12. Picno 0008S2-004. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

Picno

0008S2-004

FDS

43885.45

Range, km

1 280 215

Subspacecraft latitude/longitude, degrees

49/201

Subsolar latitude/longitude, degrees

11/193

Resolution, km/pixel

12

Filter size, pixels

17 x 17

Filter size, km

201

Scale

1:15 000 000

Figure 5-12. Picno 0008S2-004. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

[135] Figure 6-13. Picno 0523S2-004. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

Picno

0523S2-004

FDS

43894.20

Range, km

1 099 661

Subspacecraft latitude/longitude, degrees

55/217

Subsolar latitude/longitude, degrees

11/194

Resolution, km/pixel

10

Filter size, pixels

21 x 21

Filter size, km

214

Scale

1:15 000 000

Figure 6-13. Picno 0523S2-004. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

[136] Figure 6-14. Picno 1291S2-004. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

Picno

1291S2-004

FDS

43907.08

Range, km

930 228

Subspacecraft latitude/longitude, degrees

61/260

Subsolar latitude/longitude, degrees

11/196

Resolution, km/pixel

9

Filter size, pixels

23 x 23

Filter size, km

198

Scale

1:15 000 000

Figure 6-14. Picno 1291S2-004. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

[137] Figure 6-15. Picno 1678S2-004. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

Picno

1678S2-004

FDS

43913.35

Range, km

908 777

Subspacecraft latitude/longitude, degrees

58/287

Subsolar latitude/longitude, degrees

11/197

Resolution, km/pixel

8

Filter size, pixels

19 x 19

Filter size, km

160

Scale

1:15 000 000

Figure 6-15. Picno 1678S2-004. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

[138] Figure 6-16. Picno 1690S2-004. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

Picno

1690S2-004

FDS

43913.47

Range, km

908 891

Subspacecraft latitude/longitude, degrees

58/288

Subsolar latitude/longitude, degrees

11/197

Resolution, km/pixel

8

Filter size, pixels

29 x 29

Filter size, km

244

Scale

1:15 000 000

Figure 6-16. Picno 1690S2-004. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

[139] Figure 6-17. Picno 0154S2-003. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

Picno

0154S2-003

FDS

43918.11

Range, km

923 264

Subspacecraft latitude/longitude, degrees

53/302

Subsolar latitude/longitude, degrees

11/198

Resolution, km/pixel

8

Filter size, pixels

17 x 17

Filter size, km

145

Scale

1:15 000 000

Figure 6-17. Picno 0154S2-003. (a) Unfiltered image. (b) High-pass filtered image. (c) Perspective grid.

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