[go: up one dir, main page]
Wikipedia

Hellas Planitia

Hellas Planitia /ˈhɛləs pləˈnɪʃiə/ is a plain located within the huge, roughly circular impact basin Hellas[a] located in the southern hemisphere of the planet Mars.[3] Hellas is the third- or fourth-largest known impact crater in the Solar System. The basin floor is about 7,152 m (23,465 ft) deep, 3,000 m (9,800 ft) deeper than the Moon's South Pole-Aitken basin, and extends about 2,300 km (1,400 mi) east to west.[4][5] It is centered at 42°24′S 70°30′E / 42.4°S 70.5°E / -42.4; 70.5.[3] It features the lowest point on Mars, serves as a known source of global dust storms, and may have contained lakes and glaciers.[6] Hellas Planitia spans the boundary between the Hellas quadrangle and the Noachis quadrangle.

Hellas Planitia
}
Viking orbiter image mosaic of Hellas Planitia
LocationHellas quadrangle, Mars
Coordinates42°24′S 70°30′E / 42.4°S 70.5°E / -42.4; 70.5
Diameter2,300 km (1,400 mi)
Depth7,152 m (23,465 ft)
Topographic map of Hellas Planitia and its surroundings in the southern uplands, from the MOLA instrument of Mars Global Surveyor. The crater depth is 7,152 m (23,465 ft) below the standard topographic datum of Mars.[1]

Description

edit

With a diameter of about 2,300 km (1,400 mi),[7] it is the largest unambiguous well-exposed impact structure on the planet; the obscured Utopia Planitia is slightly larger (the Borealis Basin, if it proves to be an impact crater, is considerably larger). Hellas Planitia is thought to have been formed during the Late Heavy Bombardment period of the Solar System, approximately 4.1 to 3.8 billion years ago, when a protoplanet or large asteroid, suggested to be around 370 kilometres (230 mi) in diameter, hit the surface.[8][9]

The altitude difference between the rim and the bottom is over 9,000 m (30,000 ft). Despite being deeper than the Moon's South Pole-Aitken basin, Hellas' rim peaks are significantly less prominent. This may be because large Martian impacts such as Hellas induced global hot rainfall and meltwater flows that degraded crater rims, including their own.[10] The crater's depth of 7,152 m (23,465 ft)[1] below the topographic datum of Mars explains the atmospheric pressure at the bottom: 12.4 mbar (1240 Pa or 0.18 psi) during winter, when the air is coldest and reaches its highest density.[b] This is 103% higher than the pressure at the topographical datum (610 Pa, or 6.1 mbar, or 0.09 psi) and above the triple point of water, suggesting that the liquid phase could be present under certain conditions of temperature, pressure, and dissolved salt content.[12] It has been theorized that a combination of glacial action and explosive boiling may be responsible for gully features in the crater.

Some of the low elevation outflow channels extend into Hellas from the volcanic Hadriacus Mons complex to the northeast, two of which Mars Orbiter Camera images show contain gullies: Dao Vallis and Reull Vallis. These gullies are also low enough for liquid water to be transient around Martian noon, if the temperature were to rise above 0 Celsius.[13]

Hellas Planitia is antipodal to Alba Patera.[14][15][16] It and the somewhat smaller Isidis Planitia together are roughly antipodal to the Tharsis Bulge, with its enormous shield volcanoes, while Argyre Planitia is roughly antipodal to Elysium, the other major uplifted region of shield volcanoes on Mars. Whether the shield volcanoes were caused by antipodal impacts like that which produced Hellas, or if it is mere coincidence, is unknown.

 
Elevation profiles along south to north transects across Mars' Hellas basin and the Moon's South Pole-Aitken basin, created with Lunar Quickmap and Mars Quickmap
  • MOLA map showing boundaries of Hellas Planitia and other regions 
    MOLA map showing boundaries of Hellas Planitia and other regions
  • Geographic context of Hellas 
    Geographic context of Hellas
  • This elevation map shows the surrounding elevated ring of ejecta 
    This elevation map shows the surrounding elevated ring of ejecta
  • Apparent viscous flow features on the floor of Hellas, as seen by HiRISE. 
    Apparent viscous flow features on the floor of Hellas, as seen by HiRISE.
  • Twisted terrain in Hellas Planitia (actually located in Noachis quadrangle). 
    Twisted terrain in Hellas Planitia (actually located in Noachis quadrangle).
  • Twisted bands on the floor of Hellas Planitia, as seen by HiRISE under HiWish program 
    Twisted bands on the floor of Hellas Planitia, as seen by HiRISE under HiWish program
  • Twisted bands on the floor of Hellas Planitia, as seen by HiRISE under HiWish program These twisted bands are also called "taffy pull" terrain. 
    Twisted bands on the floor of Hellas Planitia, as seen by HiRISE under HiWish program These twisted bands are also called "taffy pull" terrain.

Discovery and naming

edit

Due to its size and its light coloring, which contrasts with the rest of the planet, Hellas Planitia was one of the first Martian features discovered from Earth by telescope. Before Giovanni Schiaparelli gave it the name Hellas (which in Greek means Greece), it was known as Lockyer Land, having been named by Richard Anthony Proctor in 1867 in honor of Sir Joseph Norman Lockyer, an English astronomer who, using a 16 cm (6.3 in) refractor, produced "the first really truthful representation of the planet" (in the estimation of E. M. Antoniadi).[17]

Possible glaciers

edit
 
Tongue-shaped glacier in Hellas Planitia. Ice may still exist there beneath an insulating layer of soil.
 
Close-up of glacier with a resolution of about 1 meter. The patterned ground is believed to be caused by the presence of ice.

Radar images by the Mars Reconnaissance Orbiter (MRO) spacecraft's SHARAD radar sounder suggest that features called lobate debris aprons in three craters in the eastern region of Hellas Planitia are actually glaciers of water ice lying buried beneath layers of dirt and rock.[18] The buried ice in these craters as measured by SHARAD is about 250 m (820 ft) thick on the upper crater and about 300 m (980 ft) and 450 m (1,480 ft) on the middle and lower levels respectively. Scientists believe that snow and ice accumulated on higher topography, flowed downhill, and is now protected from sublimation by a layer of rock debris and dust. Furrows and ridges on the surface were caused by deforming ice.

Also, the shapes of many features in Hellas Planitia and other parts of Mars are strongly suggestive of glaciers, as the surface looks as if movement has taken place.

Honeycomb terrain

edit

These relatively flat-lying "cells" appear to have concentric layers or bands, similar to a honeycomb. This honeycomb terrain was first discovered in the northwestern part of Hellas.[19] The geologic process responsible for creating these features remains unresolved.[20] Some calculations indicate that this formation may have been caused by ice moving up through the ground in this region. The ice layer would have been between 100 m and 1 km thick.[21][22][19] When one substance moves up through another denser substance, it is called a diapir. So, it seems that large masses of ice have pushed up layers of rock into domes that were subsequently eroded. After erosion removed the top of the layered domes, circular features remained.

  • Honeycomb terrain, as seen by HiRISE under HiWish program 
    Honeycomb terrain, as seen by HiRISE under HiWish program
  • Close, color view of honeycomb terrain, as seen by HiRISE under HiWish program 
    Close, color view of honeycomb terrain, as seen by HiRISE under HiWish program
  • Close view of honeycomb terrain, as seen by HiRISE under HiWish program 
    Close view of honeycomb terrain, as seen by HiRISE under HiWish program
  • Close view of honeycomb terrain, as seen by HiRISE under HiWish program This enlargement shows material breaking up into blocks. Arrow indicates a cube-shaped block. 
    Close view of honeycomb terrain, as seen by HiRISE under HiWish program This enlargement shows material breaking up into blocks. Arrow indicates a cube-shaped block.
  • Twisted bands on the floor of Hellas Planitia, as seen by HiRISE under HiWish program 
    Twisted bands on the floor of Hellas Planitia, as seen by HiRISE under HiWish program
  • Floor features in Hellas Planitia, as seen by HiRISE under HiWish program 
    Floor features in Hellas Planitia, as seen by HiRISE under HiWish program
  • Floor features in Hellas Planitia, as seen by HiRISE under HiWish program 
    Floor features in Hellas Planitia, as seen by HiRISE under HiWish program

Layers

edit
  • Layers in depression in crater, as seen by HiRISE under HiWish program A special type of sand ripple called Transverse aeolian ridges, TAR's are visible and labeled. 
    Layers in depression in crater, as seen by HiRISE under HiWish program A special type of sand ripple called Transverse aeolian ridges, TAR's are visible and labeled.
  • Wide view of layers, as seen by HiRISE under HiWish program 
    Wide view of layers, as seen by HiRISE under HiWish program
  • Close view of layered deposit in crater, as seen by HiRISE under HiWish program 
    Close view of layered deposit in crater, as seen by HiRISE under HiWish program
  • Layered formation, as seen by HiRISE under HiWish program 
    Layered formation, as seen by HiRISE under HiWish program
  • Close view of layers from previous image, as seen by HiRISE under HiWish program 
    Close view of layers from previous image, as seen by HiRISE under HiWish program

Interactive Mars map

edit
Map of Mars Acheron FossaeAcidalia PlanitiaAlba MonsAmazonis PlanitiaAonia PlanitiaArabia TerraArcadia PlanitiaArgentea PlanumArgyre PlanitiaChryse PlanitiaClaritas FossaeCydonia MensaeDaedalia PlanumElysium MonsElysium PlanitiaGale craterHadriaca PateraHellas MontesHellas PlanitiaHesperia PlanumHolden craterIcaria PlanumIsidis PlanitiaJezero craterLomonosov craterLucus PlanumLycus SulciLyot craterLunae PlanumMalea PlanumMaraldi craterMareotis FossaeMareotis TempeMargaritifer TerraMie craterMilankovič craterNepenthes MensaeNereidum MontesNilosyrtis MensaeNoachis TerraOlympica FossaeOlympus MonsPlanum AustralePromethei TerraProtonilus MensaeSirenumSisyphi PlanumSolis PlanumSyria PlanumTantalus FossaeTempe TerraTerra CimmeriaTerra SabaeaTerra SirenumTharsis MontesTractus CatenaTyrrhena TerraUlysses PateraUranius PateraUtopia PlanitiaValles MarinerisVastitas BorealisXanthe Terra
The image above contains clickable links Interactive image map of the global topography of Mars. Hover over the image to see the names of over 60 prominent geographic features, and click to link to them. Coloring of the base map indicates relative elevations, based on data from the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor. Whites and browns indicate the highest elevations (+12 to +8 km); followed by pinks and reds (+8 to +3 km); yellow is 0 km; greens and blues are lower elevations (down to −8 km). Axes are latitude and longitude; Polar regions are noted.


edit
  • Hellas Basin was a primary location in the 2017 video game Destiny 2. The location is part of the second game's Warmind downloadable content.
  • It is also featured as a main location in the 2016 Bethesda video game reboot Doom.
  • In Planet-Size X-Men #1, the X-Men terraform Mars, turning the basin into Lake Hellas and building the Lake Hellas Diplomatic Ring, where galactic ambassadors can meet within the Sol system.

See also

edit

Notes

edit
  1. ^ Technically, Hellas is an ‘albedo feature’.[2]
  2. ^ "... the maximum surface pressure in the baseline simulation is only 12.4 mbar. This occurs in the bottom of the Hellas basin during northern summer."[11]

References

edit
  1. ^ a b "Martian weather observation". Mars Global Surveyor. Palo Alto, California: Stanford University. Archived from the original on 31 May 2008. MGS radio science measured 11.50 mbar at 34.4° S 59.6° E −7152 meters
  2. ^ "Hellas". USGS Astrogeology Science Center. Gazetteer of Planetary Nomenclature. United States Geological Survey. Retrieved 10 March 2015.
  3. ^ a b "Hellas Planitia". Gazetteer of Planetary Nomenclature. USGS Astrogeology Science Center. Retrieved 10 March 2015.
  4. ^ The part below zero datum, see Geography of Mars#Zero elevation
  5. ^ "Section 19-12". Goddard Space Flight Center. Remote sensing tutorial. NASA. Archived from the original on 30 October 2004.
  6. ^ Bleamaster, Leslie F. III; Crown, David A. (19 March 2010). "Geologic Map of MTM -40277, -45277, -40272, and -45272 Quadrangles, Eastern Hellas Planitia Region of Mars". U.S. Geological Survey Publications Warehouse. Retrieved 30 June 2024.
  7. ^ Schultz, Richard A.; Frey, Herbert V. (1990). "A new survey of multi-ring impact basins on Mars". Journal of Geophysical Research. 95: 14175–14189. Bibcode:1990JGR....9514175S. doi:10.1029/JB095iB09p14175. Archived from the original on 30 March 2012. Retrieved 16 November 2008.
  8. ^ Acuña, M. H.; et al. (1999). "Global Distribution of Crustal Magnetization Discovered by the Mars Global Surveyor MAG/ER Experiment". Science. 284 (5415): 790–793. Bibcode:1999Sci...284..790A. doi:10.1126/science.284.5415.790. PMID 10221908.
  9. ^ Branco, Hely C.; Miljkovic, Katarina; Plesa, Ana‐Catalina (April 2024). "New Numerically Derived Scaling Relationships for Impact Basins on Mars". Journal of Geophysical Research: Planets. 129 (4). doi:10.1029/2023JE008217. ISSN 2169-9097.
  10. ^ Head, J.W.; Palumbo, A.M. (2018). "Impact cratering as a cause of climate change, surface alteration, and resurfacing". Meteoritics & Planetary Science. 53, Nr4: 687–725. doi:10.1111/maps.13001.
  11. ^ Haberle, Robert M.; McKay, Christopher P.; Schaeffer, James; Cabrol, Nathalie A.; Grin, Edmon A.; Zent, Aaron P.; Quinn, Richard (25 October 2001). "On the possibility of liquid water on present-day Mars". Journal of Geophysical Research. 106 (EL0): 23, 317–23, 326. Bibcode:2001JGR...10623317H. doi:10.1029/2000JE001360.
  12. ^ "Making a splash on Mars" (Press release). NASA. 29 June 2000. Archived from the original on 1 May 2017. Retrieved 12 July 2017.
  13. ^ Heldmann, Jennifer L.; et al. (2005). "Formation of Martian gullies by the action of liquid water flowing under current Martian environmental conditions". Journal of Geophysical Research. 110 (E5): E05004. Bibcode:2005JGRE..110.5004H. CiteSeerX 10.1.1.596.4087. doi:10.1029/2004JE002261. S2CID 1578727. – page 2, para 3: Martian Gullies Mars#References
  14. ^ Peterson, J. E. (March 1978). "Antipodal Effects of Major Basin-Forming Impacts on Mars". Lunar and Planetary Science. IX: 885–886. Bibcode:1978LPI.....9..885P.
  15. ^ Williams, D.A.; Greeley, R. (1991). "The Formation of Antipodal-Impact Terrains on Mars" (PDF). Lunar and Planetary Science. XXII: 1505–1506. Retrieved 4 July 2012.
  16. ^ Williams, D.A.; Greeley, R. (August 1994). "Assessment of Antipodal-Impact Terrains on Mars". Icarus. 110 (2): 196–202. Bibcode:1994Icar..110..196W. doi:10.1006/icar.1994.1116.
  17. ^ Sheehan, William (1996). The Planet Mars: A history of observation and discovery. Tucson, AZ: University of Arizona Press. Chapter 4. ISBN 9780816516414. Retrieved 19 February 2021.
  18. ^ "PIA11433: Three craters". NASA. Retrieved 24 November 2008.
  19. ^ a b Bernhardt, H.; et al. (2016). "The honeycomb terrain on the Hellas basin floor, Mars: A case for salt or ice diapirism: Hellas honeycombs as salt / ice diapirs". J. Geophys. Res. 121 (4): 714–738. Bibcode:2016JGRE..121..714B. doi:10.1002/2016je005007.
  20. ^ "HiRISE | to Great Depths (ESP_049330_1425)".
  21. ^ Weiss, D.; Head, J. (2017). "Hydrology of the Hellas basin and the early Mars climate: Was the honeycomb terrain formed by salt or ice diapirism?". Lunar and Planetary Science. XLVIII: 1060.
  22. ^ Weiss, D.; Head, J. (2017). "Salt or ice diapirism origin for the honeycomb terrain in Hellas basin, Mars?: Implications for the early martian climate". Icarus. 284: 249–263. Bibcode:2017Icar..284..249W. doi:10.1016/j.icarus.2016.11.016.

Further reading

edit
edit
 
Wikimedia Commons has media related to Hellas Planitia.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Hellas_Planitia&oldid=1256731500"