Cryovolcano

A cryovolcano (sometimes informally called an ice volcano) 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 (such as Pluto[2]). 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.[3][4] In addition, although they are not known to form volcanoes, ice geysers have been observed on Enceladus and potentially Triton.

For ice mounds on Earth, see Ice volcano.
Doom Mons, one of the most reliably identified cryovolcanoes on Saturn's moon Titan[1]

One potential energy source on some solar system bodies for melting ice and producing cryovolcanoes is tidal friction.[5]

Signs of past warming of the Kuiper belt object Quaoar[6] have led scientists to speculate that it exhibited cryovolcanism in the past. Radioactive decay could provide the energy necessary for such activity, as cryovolcanoes could emit water mixed with ammonia, which would melt at 180 K (−95 °C) and create an extremely cold liquid that would flow out of the volcano.

Observations
Plumes of Enceladus, feeding Saturn's E Ring, seem to arise from the "Tiger Stripes" near the south pole.

On November 27, 2005, Cassini photographed geysers on the south pole of Enceladus.[7] (See also: Enceladus (cryovolcanism).)

Indirect evidence of cryovolcanic activity was later observed on several other icy moons of the Solar System, including Europa, Titan, Ganymede, and Miranda. Cassini has observed several features thought to be cryovolcanoes on Titan, notably Doom Mons with adjacent Sotra Patera, a feature regarded as "the very best evidence, by far, for volcanic topography anywhere documented on an icy satellite."[8] Cryovolcanism is one process hypothesized to be a significant source of the methane found in Titan's atmosphere.[9]

In 2007, observations by the Gemini Observatory showing patches of ammonia hydrates and water crystals on the surface of Pluto's moon Charon suggested the presence of active cryovolcanoes or cryogeysers.[10][11] Subsequent observations by New Horizons in 2015 found that Charon has a youthful surface, supporting this idea.[12] Pluto itself has two features that have been identified as possible cryovolcanoes, being mountains with indented peaks.[13]

In 2015, two distinct bright spots inside a crater of the dwarf planet Ceres were imaged by the Dawn spacecraft, leading to speculation about a possible cryovolcanic origin.[14] In September 2016, NASA JPL and NASA Goddard scientists released findings that the large Ahuna Dome on Ceres is a "volcanic dome unlike any seen elsewhere in the solar system. [The large] mountain is likely volcanic in nature. Specifically, it would be a cryovolcano -- a volcano that erupts a liquid made of volatiles such as water, instead of silicates. ... the only known example of a cryovolcano that potentially formed from a salty mud mix, and that formed in the geologically recent past."[15] In addition, at least some of Ceres' well-known bright spots (notably including the ones in Occator crater) are likely also cryovolcanic in origin.[16][17] A study published in March 2017 suggests that Occator's most recent large eruption occurred about 4 million years ago and thus that Ceres may still be active.[18]

Cryovolcanism on Enceladus
  • One possible scheme for Enceladus's cryovolcanism
    One possible scheme for Enceladus's cryovolcanism
  • Possible origins of methane found in plumes through its subsurface ocean
    Possible origins of methane found in plumes through its subsurface ocean
  • Chemical composition of the plumes of Enceladus
    Chemical composition of the plumes of Enceladus

See also

References
  1. Lopes, R. M. C.; Kirk, R. L.; Mitchell, K. L.; LeGall, A.; Barnes, J. W.; Hayes, A.; Kargel, J.; Wye, L.; Radebaugh, J.; Stofan, E. R.; Janssen, M. A.; Neish, C. D.; Wall, S. D.; Wood, C. A.; Lunine, Jonathan I.; Malaska, M. J. (19 March 2013). "Cryovolcanism on Titan: New results from Cassini RADAR and VIMS" (PDF). Journal of Geophysical Research: Planets. 118 (3): 416–435. Bibcode:2013JGRE..118..416L. doi:10.1002/jgre.20062.
  2. Witze, Alexandra (2015). "Ice volcanoes may dot Pluto's surface". Nature. doi:10.1038/nature.2015.18756. S2CID 182698872.
  3. Fagents, Sarah (2003-12-27). "Considerations for Effusive Cryovolcanism on Europa: The Post-Galileo Perspective". Journal of Geophysical Research. 108 (E12): 5139. Bibcode:2003JGRE..108.5139F. doi:10.1029/2003JE002128.
  4. Quick, Lynnae C.; Glaze, Lori S.; Baloga, Stephen M. (2017-03-01). "Cryovolcanic Emplacement of Domes on Europa". Icarus. 284: 477–488. Bibcode:2017Icar..284..477Q. doi:10.1016/j.icarus.2016.06.029.
  5. Greenberg, Richard (2002). "Tidal-tectonic processes and their implications for the character of Europa's icy crust". Reviews of Geophysics. 40 (2). doi:10.1029/2000rg000096. ISSN 8755-1209.
  6. Jewitt, D.C.; J. Luu (2004). "Crystalline water ice on the Kuiper belt object (50000) Quaoar". Nature. 432 (7018): 731–3. Bibcode:2004Natur.432..731J. doi:10.1038/nature03111. PMID 15592406. S2CID 4334385.. Reprint on Jewitt's site (pdf)
  7. Chang, Kenneth (March 12, 2015). "Suddenly, It Seems, Water Is Everywhere in Solar System". The New York Times. Retrieved March 12, 2015.
  8. "Cassini Spots Potential Ice Volcano on Saturn Moon". NASA, December 14, 2010
  9. Media Relations Office: Cassini Imaging Central Laboratory For Operations (2009). "Cassini Finds Hydrocarbon Rains May Fill The Lakes". Space Science Institute, Boulder, Colorado. Archived from the original on 25 July 2011. Retrieved 4 March 2015.
  10. "Charon: An ice machine in the ultimate deep freeze". Spaceflight Now. July 17, 2007. Retrieved 18 July 2007.
  11. Cook; Desch, Steven J.; Roush, Ted L.; Trujillo, Chadwick A.; Geballe, T. R.; et al. (2007). "Near-Infrared Spectroscopy of Charon: Possible Evidence for Cryovolcanism on Kuiper Belt Objects". The Astrophysical Journal. 663 (2): 1406–1419. Bibcode:2007ApJ...663.1406C. doi:10.1086/518222.
  12. Beatty, Kelly (2 October 2015). "Charon: Cracked, Cratered, and Colorful". Sky and Telescope. Retrieved 2015-10-03.
  13. Witze, A. (2015-11-09). "Icy volcanoes may dot Pluto's surface". Nature News. doi:10.1038/nature.2015.18756. S2CID 182698872. Retrieved 2015-11-09.
  14. O'Neill, Ian (25 February 2015). "Ceres' Mystery Bright Dots May Have Volcanic Origin". Discovery Communications. Retrieved 1 March 2015.
  15. "Ceres' Geological Activity, Ice Revealed in New Research". NASA JPL. September 1, 2016. Archived from the original on 2016-09-04.
  16. Staff (September 5, 2016). "Ceres: The tiny world where volcanoes erupt ice". SpaceDaily.
  17. Quick, Lynnae C.; Buczkowski, Debra L.; Ruesch, Ottaviano; Scully, Jennifer E. C.; Castillo-Rogez, Julie; Raymond, Carol A.; Schenk, Paul M.; Sizemore, Hanna G.; Sykes, Mark V. (2019-03-01). "A Possible Brine Reservoir Beneath Occator Crater: Thermal and Compositional Evolution and Formation of the Cerealia Dome and Vinalia Faculae". Icarus. 320: 119–135. Bibcode:2019Icar..320..119Q. doi:10.1016/j.icarus.2018.07.016. S2CID 125508484.
  18. Grossman, David (March 6, 2017). "The Ice Volcanoes of Ceres Were Highly Active a Few Million Years Ago". Popular Mechanics.
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