Tiger stripes (Enceladus)

Last updated
Cassini view of Enceladus's south pole. The tiger stripes, from lower left to upper right, are the Damascus, Baghdad, Cairo, Alexandria and Camphor sulci. Enceladus Tiger Stripes Up Close PIA06247.jpg
Cassini view of Enceladus's south pole. The tiger stripes, from lower left to upper right, are the Damascus, Baghdad, Cairo, Alexandria and Camphor sulci.

The tiger stripes of Enceladus consist of four sub-parallel, linear depressions in the south polar region of the Saturnian moon. [1] [2] First observed on May 20, 2005, by the Cassini spacecraft's Imaging Science Sub-system (ISS) camera (though seen obliquely during an early flyby), the features are most notable in lower resolution images by their brightness contrast from the surrounding terrain. [3] Higher resolution observations were obtained by Cassini's various instruments during a close flyby of Enceladus on July 14, 2005. These observations revealed the tiger stripes to be low ridges with a central fracture. [2] Observations from the Composite Infrared Spectrometer (CIRS) instrument showed the tiger stripes to have elevated surface temperatures, indicative of present-day cryovolcanism on Enceladus centered on the tiger stripes. [4]



The name tiger stripes is an unofficial term given to these four features based on their distinctive albedo. Enceladean sulci (subparallel furrows and ridges), like Samarkand Sulci and Harran Sulci, have been named after cities or countries referred to in The Arabian Nights . Accordingly, in November 2006, the tiger stripes were assigned the official names Alexandria Sulcus, Cairo Sulcus, Baghdad Sulcus and Damascus Sulcus (Camphor Sulcus is a smaller feature that branches off Alexandria Sulcus). [5] Baghdad and Damascus sulci are the most active, while Alexandria Sulcus is the least active.

Appearance and geology

Composite map of the southern hemisphere of Enceladus (2007) Enceladus south pole SE15.png
Composite map of the southern hemisphere of Enceladus (2007)

Images from the ISS camera onboard Cassini revealed the 4 tiger stripes to be a series of sub-parallel, linear depressions flanked on each side by low ridges. [2] On average, each tiger stripe depression is 130 kilometers long, 2 kilometers wide, and 500 meters deep. The flanking ridges are, on average, 100 meters tall and 2–4 kilometers wide. Given their appearance and their geologic setting within a heavily tectonically deformed region, the tiger stripes are likely to be tectonic fractures. [2] However, their correlation with internal heat and a large, water vapor plume suggests that tiger stripes might be the result of fissures in Enceladus' lithosphere. The stripes are spaced approximately 35 kilometers apart. The ends of each tiger stripe differ in appearance between the anti-Saturnian and sub-Saturnian hemisphere. On the anti-Saturnian hemisphere, the stripes terminate in hook-shaped bends, while the sub-Saturnian tips bifurcate dendritically. [2]

Virtually no impact craters have been found on or near the tiger stripes, suggesting a very young surface age. Surface age estimates based on crater counting yielded an age of 4–100 million years assuming a lunar-like cratering flux and 0.5-1 million years assuming a constant cratering flux. [2]


Another aspect that distinguishes the tiger stripes from the rest of the surface of Enceladus are their unusual composition. Nearly the entire surface of Enceladus is covered in a blanket of fine-grained water ice. The ridges that surround the tiger stripes are often covered in coarse-grained, crystalline water ice. [2] [6] This material appears dark in the Cassini camera's IR3 filter (central wavelength 930 nanometers), giving the tiger stripes a dark appearance in clear-filter images and a blue-green appearance in false-color, near-ultraviolet, green, near-infrared images. The Visual and Infrared Mapping Spectrometer (VIMS) instrument also detected trapped carbon dioxide ice and simple organics within the tiger stripes. [6] Simple organic material has not been detected anywhere else on the surface of Enceladus.

The detection of crystalline water ice along the tiger stripes also provides an age constraint. Crystalline water ice gradually loses its crystal structure after being cooled and subjected to the Saturnian magnetospheric environment. Such a transformation into finer-grained, amorphous water ice is thought to take a few decades to a thousand years. [7]


Enceladus - South Pole - Geyser basin (August 10, 2014). PIA17183-Enceladus-SouthPole-Cassini-20100810.jpg
Enceladus - South Pole - Geyser basin (August 10, 2014).
Enceladus - South Pole - Geysers spray water from many locations along the "tiger stripes". Enceladus geysers June 2009.jpg
Enceladus - South Pole - Geysers spray water from many locations along the "tiger stripes".

Observations by Cassini during the July 14, 2005 flyby revealed a cryovolcanically active region on Enceladus centered on the tiger stripe region. The CIRS instrument revealed the entire tiger stripe region (south of 70° South latitude) to be warmer than expected if the region were heated solely from sunlight. [4] Higher resolution observations revealed that the hottest material near Enceladus' south pole is located within the tiger stripe fractures. Color temperatures between 113 and 157 kelvins have been obtained from the CIRS data, significantly warmer than the expected 68 kelvins for this region of Enceladus.

Data from the ISS, Ion and Neutral Mass Spectrometer (INMS), Cosmic Dust Analyser (CDA) and CIRS instruments show that a plume of water vapor and ice, methane, carbon dioxide, and nitrogen emanates from a series of jets located within the tiger stripes. [9] [10] The amount of material within the plume suggests that the plume is generated from a near-surface body of liquid water. [2] Over 100 geysers have been identified on Enceladus. [8]

Alternatively, Kieffer et al. (2006) suggest that Enceladus' geysers originate from clathrate hydrates, where carbon dioxide, methane, and nitrogen are released when exposed to the vacuum of space by the fractures. [11]

Relation to E-Ring of Saturn

Plumes from the moon Enceladus, which seems similar in chemical makeup to comets, [12] have been shown to be the source of the material in the E Ring. [13] The E Ring is the widest and outermost ring of Saturn (except for the tenuous Phoebe ring). It is an extremely wide but diffuse disk of microscopic icy or dusty material. The E ring is distributed between the orbits of Mimas and Titan. [14]

Numerous mathematical models show that this ring is unstable, with a lifespan between 10,000 and 1,000,000 years, therefore, particles composing it must be constantly replenished. [15] Enceladus is orbiting inside this ring, in a place where it is narrowest but present in its highest density, raising suspicion since the 1980s that Enceladus is the main source of particles for the E ring. [16] [17] [18] [19] This hypothesis was confirmed by Cassini's first two close flybys in 2005. [20] [21]

Saturn's Rings PIA03550.jpg
Saturn's Rings PIA03550.jpg
View of Enceladus's orbit from the side, showing Enceladus in relation to Saturn's E ring
Eruptions on Enceladus may seem to be "discrete" jets, but may be "curtain" eruptions instead
(video animation) PIA19061-SaturnMoonEnceladus-CurtainNotDiscrete-Eruptions-20150506.jpg
Eruptions on Enceladus may seem to be "discrete" jets, but may be "curtain" eruptions instead
(video animation)

Related Research Articles

<span class="mw-page-title-main">Saturn</span> Sixth planet from the Sun

Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine-and-a-half times that of Earth. It has only one-eighth the average density of Earth, but is over 95 times more massive.

<span class="mw-page-title-main">Rhea (moon)</span> Moon of Saturn

Rhea is the second-largest moon of Saturn and the ninth-largest moon in the Solar System, with a surface area that is comparable to the area of Australia. It is the smallest body in the Solar System for which precise measurements have confirmed a shape consistent with hydrostatic equilibrium. It was discovered in 1672 by Giovanni Domenico Cassini.

<i>Cassini–Huygens</i> Space research mission sent to the Saturnian system

Cassini–Huygens, commonly called Cassini, was a space-research mission by NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to send a space probe to study the planet Saturn and its system, including its rings and natural satellites. The Flagship-class robotic spacecraft comprised both NASA's Cassini space probe and ESA's Huygens lander, which landed on Saturn's largest moon, Titan. Cassini was the fourth space probe to visit Saturn and the first to enter its orbit, where it stayed from 2004 to 2017. The two craft took their names from the astronomers Giovanni Cassini and Christiaan Huygens.

<span class="mw-page-title-main">Tethys (moon)</span> Moon of Saturn

Tethys, or Saturn III, is a mid-sized moon of Saturn about 1,060 km (660 mi) across. It was discovered by G. D. Cassini in 1684 and is named after the titan Tethys of Greek mythology.

<span class="mw-page-title-main">Iapetus (moon)</span> Moon of Saturn

Iapetus is a moon of Saturn. With an estimated diameter of 1,469 km, it is the third-largest moon of Saturn and the eleventh-largest in the Solar System. Named after the Titan Iapetus, the moon was discovered in 1671 by Giovanni Domenico Cassini.

<span class="mw-page-title-main">Calypso (moon)</span> Trojan moon of Saturn

Calypso is a moon of Saturn. It was discovered in 1980, from ground-based observations, by Dan Pascu, P. Kenneth Seidelmann, William A. Baum, and Douglas G. Currie, and was provisionally designated S/1980 S 25. Several other apparitions of it were recorded in the following months: S/1980 S 29, S/1980 S 30, S/1980 S 32, and S/1981 S 2. In 1983 it was officially named after Calypso of Greek mythology. It is also designated Saturn XIV or Tethys C.

<span class="mw-page-title-main">Dione (moon)</span> Moon of Saturn

Dione, also designated Saturn IV, is the fourth-largest moon of Saturn. Its trailing hemisphere is marked by large ice cliffs called chasmata and is also darkened compared to the leading hemisphere. Based on its density, Dione’s interior is likely a combination of silicate rock and water ice in nearly equal parts by mass. The moon was discovered by Italian astronomer Giovanni Domenico Cassini in 1684 and is named after the Titaness Dione in Greek mythology.

<span class="mw-page-title-main">Enceladus</span> Natural satellite orbiting Saturn

Enceladus is the sixth-largest moon of Saturn. It is about 500 kilometers in diameter, about a tenth of that of Saturn's largest moon, Titan. It is mostly covered by fresh, clean ice, making it one of the most reflective bodies of the Solar System. Consequently, its surface temperature at noon reaches only −198 °C, far colder than a light-absorbing body would be. Despite its small size, Enceladus has a wide range of surface features, ranging from old, heavily cratered regions to young, tectonically deformed terrain.

<span class="mw-page-title-main">Moons of Saturn</span> Natural satellites of the planet Saturn

The moons of Saturn are numerous and diverse, ranging from tiny moonlets only tens of meters across to the enormous Titan, which is larger than the planet Mercury. There are 146 moons with confirmed orbits, the most of any planet in the solar system. This number does not include the many thousands of moonlets embedded within Saturn's dense rings, nor hundreds of possible kilometer-sized distant moons that were seen through telescopes but not recaptured. Seven Saturnian moons are large enough to have collapsed into a relaxed, ellipsoidal shape, though only one or two of those, Titan and possibly Rhea, are currently in hydrostatic equilibrium. Three moons are particularly notable. Titan is the second-largest moon in the Solar System, with a nitrogen-rich Earth-like atmosphere and a landscape featuring river networks and hydrocarbon lakes. Enceladus emits jets of ice from its south-polar region and is covered in a deep layer of snow. Iapetus has contrasting black and white hemispheres as well as an extensive ridge of equatorial mountains among the tallest in the solar system.

<span class="mw-page-title-main">Rings of Saturn</span> Planar assemblage of icy particles orbiting Saturn

The rings of Saturn are the most extensive ring system of any planet in the Solar System. They consist of countless small particles, ranging in size from micrometers to meters, that orbit around Saturn. The ring particles are made almost entirely of water ice, with a trace component of rocky material. There is still no consensus as to their mechanism of formation. Although theoretical models indicated that the rings were likely to have formed early in the Solar System's history, newer data from Cassini suggested they formed relatively late.

<span class="mw-page-title-main">Cryovolcano</span> Type of volcano that erupts volatiles such as water, ammonia or methane, instead of molten rock

A cryovolcano is a type of volcano that erupts volatiles such as water, ammonia or methane into an extremely cold environment that is at or below their freezing point. The process of formation is known as cryovolcanism. Collectively called cryomagma, cryolava or ice-volcanic melt, these substances are usually liquids and can form plumes, but can also be in vapour form. After the eruption, cryomagma is expected to condense to a solid form when exposed to very low surrounding temperatures. Cryovolcanoes may potentially form on icy moons and other objects with abundant water past the Solar System's snow line. A number of features have been identified as possible cryovolcanoes on Pluto, Titan and Ceres, and a subset of domes on Europa may have cryovolcanic origins. In addition, although they are not known to form volcanoes, ice geysers have been observed on Enceladus and potentially Triton.

<span class="mw-page-title-main">Polydeuces (moon)</span> Trojan moon of Saturn

Polydeuces, also designated Saturn XXXIV, is a small trojan moon of Saturn occupying the trailing L5 Lagrange point of Dione. It was discovered by the Cassini Imaging Science Team in images taken by the Cassini space probe on 21 October 2004. With a mean diameter of about 3 km (1.9 mi), Polydeuces is thought to have a smooth surface coated with fine, icy particles accumulated from the cryovolcanic plumes of Enceladus. In its orbit around Saturn, Polydeuces periodically drifts away from Dione's Lagrange point due to gravitational perturbations by other nearby moons of Saturn. Of the four known trojan moons of Saturn, Polydeuces exhibits the largest displacement from its Lagrange point.

<span class="mw-page-title-main">Carolyn Porco</span> American planetary scientist

Carolyn C. Porco is an American planetary scientist who explores the outer Solar System, beginning with her imaging work on the Voyager missions to Jupiter, Saturn, Uranus and Neptune in the 1980s. She led the imaging science team on the Cassini mission in orbit around Saturn. She is an expert on planetary rings and the Saturnian moon, Enceladus.

<span class="mw-page-title-main">Magnetosphere of Saturn</span> Cavity in the solar wind the sixth planet creates

The magnetosphere of Saturn is the cavity created in the flow of the solar wind by the planet's internally generated magnetic field. Discovered in 1979 by the Pioneer 11 spacecraft, Saturn's magnetosphere is the second largest of any planet in the Solar System after Jupiter. The magnetopause, the boundary between Saturn's magnetosphere and the solar wind, is located at a distance of about 20 Saturn radii from the planet's center, while its magnetotail stretches hundreds of Saturn radii behind it.

<span class="mw-page-title-main">Labtayt Sulci</span>

Labtayt Sulci is a system of deep fractures on Saturn's moon Enceladus. Labtayt Sulci was first seen in low-resolution Voyager 1 images, but was observed in much more detail by the Cassini spacecraft during its February 2005 flyby of Enceladus. It is centered at 28.0° South Latitude, 284.0° West Longitude and is approximately 162 kilometers long, 4 kilometers wide, and 1 kilometer deep. The association between a cusp along the South Polar terrain boundary and Labtayt suggests that the fracture was forced open by thrust faulting where the fracture intersects with Cashmere Sulci.

<span class="mw-page-title-main">Exploration of Saturn</span> Overview of the exploration of Saturn

The exploration of Saturn has been solely performed by crewless probes. Three missions were flybys, which formed an extended foundation of knowledge about the system. The Cassini–Huygens spacecraft, launched in 1997, was in orbit from 2004 to 2017.

Journey to Enceladus and Titan (JET) is an astrobiology mission concept to assess the habitability potential of Enceladus and Titan, moons of Saturn.

Life Investigation For Enceladus (LIFE) was a proposed astrobiology mission concept that would capture icy particles from Saturn's moon Enceladus and return them to Earth, where they could be studied in detail for signs of life such as biomolecules.

THEO is a feasibility study for a New Frontiers class orbiter mission to Enceladus that would directly sample its south pole water plumes in order to study its internal habitability and to search for biosignatures. Specifically, it would take advantage of the direct sampling opportunities of a subsurface ocean.

<span class="mw-page-title-main">Cosmic Dust Analyzer</span> Space instrument on Cassini/Huygen

The Cosmic Dust Analyzer (CDA) on the Cassini mission is a large-area multi-sensor dust instrument that includes a chemical dust analyzer, a highly reliable impact ionization detector, and two high rate polarized polyvinylidene fluoride (PVDF) detectors. During 6 years en route to Saturn the CDA analysed the interplanetary dust cloud, the stream of interstellar dust, and Jupiter dust streams. During 13 years in orbit around Saturn the CDA studied the E ring, dust in the plumes of Enceladus, and dust in Saturn's environment.


  1. Drake, Nadia (9 December 2019). "How an Icy Moon of Saturn Got Its Stripes - Scientists have developed an explanation for one of the most striking features of Enceladus, an ocean world that has the right ingredients for life". The New York Times . Retrieved 11 December 2019.
  2. 1 2 3 4 5 6 7 8 Porco, C. C.; Helfenstein, P.; Thomas, P. C.; Ingersoll, A. P.; Wisdom, J.; West, R.; Neukum, G.; Denk, T.; Wagner, R. (10 March 2006). "Cassini Observes the Active South Pole of Enceladus". Science. 311 (5766): 1393–1401. Bibcode:2006Sci...311.1393P. doi:10.1126/science.1123013. PMID   16527964. S2CID   6976648.
  3. J. Perry (23 May 2005). "New Enceladus Raw Images" . Retrieved 22 March 2006.
  4. 1 2 Spencer, J. R.; Pearl, J. C.; Segura, M.; Flasar, F. M.; Mamoutkine, A.; Romani, P.; Buratti, B. J.; Hendrix, A. R.; Spilker, L. J.; Lopes, R. M. C. (2006). "Cassini Encounters Enceladus: Background and the Discovery of a South Polar Hot Spot" . Science. 311 (5766): 1401–1405. Bibcode:2006Sci...311.1401S. doi:10.1126/science.1121661. PMID   16527965. S2CID   44788825.
  5. "New Names Approved for Use on Enceladus". SaturnToday.Com . SpaceRef Interactive Inc. 2006-11-17. Retrieved 2008-09-20.{{cite web}}: External link in |work= (help)
  6. 1 2 R. H. Brown et al., Science311 1425 (2006).
  7. Cassini Finds Enceladus Tiger Stripes are Really Cubs Archived 2008-10-18 at the Wayback Machine . Retrieved March 22, 2006.
  8. 1 2 Dyches, Preston; Brown, Dwayne; et al. (July 28, 2014). "Cassini Spacecraft Reveals 101 Geysers and More on Icy Saturn Moon". NASA . Retrieved July 29, 2014.
  9. NASA's Cassini Images Reveal Spectacular Evidence of an Active Moon Archived 2011-10-29 at the Wayback Machine . 6 December 2005. Retrieved March 22, 2006.
  10. "Jet Spots in Tiger Stripes". CICLOPS web site . NASA/JPL/GSFC/SwRI/SSI. 2008-03-26. Archived from the original on 2011-07-25. Retrieved 2009-08-30.{{cite web}}: External link in |work= (help)
  11. Kieffer, Susan W.; Xinli Lu; et al. (2006). "A Clathrate Reservoir Hypothesis for Enceladus' South Polar Plume". Science. 314 (5806): 1764–1766. Bibcode:2006Sci...314.1764K. doi:10.1126/science.1133519. PMID   17170301. S2CID   41743663.
  12. Battersby, Stephen (26 March 2008). "Saturn's moon Enceladus surprisingly comet-like". New Scientist . Retrieved 16 April 2015.
  13. "Icy Tendrils Reaching into Saturn Ring Traced to Their Source". NASA News. 14 April 2015. Archived from the original on 2015-04-16. Retrieved 2015-04-15.
  14. Hedman, M. M.; Burns, J. A.; et al. (2012). "The three-dimensional structure of Saturn's E ring". Icarus. 217 (1): 322–338. arXiv: 1111.2568 . Bibcode:2012Icar..217..322H. doi:10.1016/j.icarus.2011.11.006. S2CID   1432112.
  15. Vittorio, Salvatore A. (July 2006). "Cassini visits Enceladus: New light on a bright world". Cambridge Scientific Abstracts (CSA). CSA. Archived from the original on 2014-04-28. Retrieved 2014-04-27.
  16. Baum, W. A.; Kreidl, T. (July 1981). "Saturn's E ring: I. CCD observations of March 1980". Icarus. 47 (1): 84–96. Bibcode:1981Icar...47...84B. doi:10.1016/0019-1035(81)90093-2.
  17. Haff, P. K.; Eviatar, A.; et al. (1983). Haff, P. K.; Eviatar, A.; Siscoe, G. L. (eds.). "Ring and plasma: Enigmae of Enceladus". Icarus. 56 (3): 426–438. Bibcode:1983Icar...56..426H. doi:10.1016/0019-1035(83)90164-1.
  18. Pang, Kevin D.; Voge, Charles C.; et al. (1984). "The E ring of Saturn and satellite Enceladus". Journal of Geophysical Research. 89: 9459–9470. Bibcode:1984JGR....89.9459P. doi:10.1029/JB089iB11p09459.
  19. Blondel, Philippe; Mason, John (August 23, 2006). Solar System Update. Springer Science. pp. 241–243.
  20. Spahn, F.; Schmidt, J; et al. (2006). "Cassini Dust Measurements at Enceladus and Implications for the Origin of the E Ring". Science. 311 (5766): 1416–1418. Bibcode:2006Sci...311.1416S. CiteSeerX . doi:10.1126/science.1121375. PMID   16527969. S2CID   33554377.
  21. Cain, Fraser (5 February 2008). "Enceladus is Supplying Ice to Saturn's A-Ring". NASA. Universe Today. Retrieved 2014-04-26.