HiWish is a program created by NASA so that anyone can suggest a place for the HiRISE camera on the Mars Reconnaissance Orbiter to photograph.[1] It was started in January 2010. In the first few months of the program 3000 people signed up to use HiRISE.[2][3] The first images were released in April 2010.[4] Over 5000 suggestions were made by the public; suggestions were made for targets in each of the 30 quadrangles of Mars. Selected images released were used for three talks at the 16th Annual International Mars Society Convention. Below are some of the over 1100 images that have been released from the HiWish program as of March 2015.

Glacial features

Some landscapes look just like glaciers moving out of mountain valleys on Earth. Some have a hallowed out appearance, looking like a glacier after almost all the ice has disappeared. What is left are the moraines—the dirt and debris carried by the glacier. The center is hollowed out because the ice is mostly gone.[5] These supposed alpine glaciers have been called glacier-like forms (GLF) or glacier-like flows (GLF).[6] Glacier-like forms are a later and maybe more accurate term because we cannot be sure the structure is currently moving.[7]

Main article: Glaciers on Mars

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Martian glacier moving down a valley, as seen by HiRISE under HiWish program.

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  • Possible glacier flowing down a valley and spreading out on a plain. Rectangle shows a portion that is enlarged in the next image.

  • Enlargement of the area in the rectangle in the previous image. This area would be called a moraine in an alpine glacier on Earth.

  • Well-developed hollows of concentric crater fill, as seen by HiRISE under the HiWish program.

Ancient rivers?

There is great deal of evidence that water once flowed in river valleys on Mars. Pictures from orbit show winding valleys, branched valleys, and even meanders with oxbow lakes.[8] Some are visible in the pictures below.

  • Channel on floor of Newton Crater, as seen by HiRISE under HiWish program.

  • Branched channel, as seen by HiRISE under HiWish program.

  • Branched channel, as seen by HiRISE under HiWish program.

  • Oxbow lake, as seen by HiRISE under HiWish program.

  • Valleys as seen by HiRISE under HiWish program

  • Channel in Arabia, as seen by HiRISE under HiWish program.

New Crater

  • HiRISE images showing discovery of a new crater with HiWish program

  • New crater, as seen by HiRISE under HiWish program. The new crater indicated with the white arrow is about 10 yards across and was probably created by the collision with an object the size of a large watermelon. This crater did not appear in earlier images of the same region.

Sand dunes

Many locations on Mars have sand dunes. The dunes are covered by a seasonal carbon dioxide frost that forms in early autumn and remains until late spring. Many martian dunes strongly resemble terrestrial dunes but images acquired by the High-Resolution Imaging Science Experiment on the Mars Reconnaissance Orbiter have shown that martian dunes in the north polar region are subject to modification via grainflow triggered by seasonal CO2 sublimation, a process not seen on Earth. Many dunes are black because they are derived from the dark volcanic rock basalt. Extraterrestrial sand seas such as those found on Mars are referred to as “undae” from the Latin for waves.

  • Dunes in two craters, as seen by HiRISE under the HiWish program.

  • Dunes among craters, as seen by HiRISE under HiWish program. Some of these are barchans.

  • Dunes on a crater floor, as seen by HiRISE under HiWish program. Most of these are barchans. Box shows location of next image.

  • Dunes on a crater floor, as seen by HiRISE under HiWish program. Most of these are barchans. Note: this is an enlargement of the center of the previous image.

  • Dunes, as seen by HiRISE under HiWish program. Location is Eridania quadrangle.

Landing site

Some of the targets suggested became possible sites for a Rover Mission in 2020. The targets were in Firsoff (crater). This crater was picked as one of 26 locations considered for a mission that will look for signs of life and gather samples for a later return to Earth.[9][10][11]

  • Layers in Firsoff Crater, as seen by HiRISE under HiWish program Note: this image field can be found in the previous image of the layers in Firsoff Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).

  • Close-up of layers in Firsoff Crater, as seen by HiRISE Note: this is an enlargement of the previous image of Firsoff Crater.

  • Layers in Firsoff crater with a box showing the size of a football field Picture taken by HiRISE under HiWish program.

  • Layers and faults in Firsoff Crater, as seen by HiRISE under HiWish program. Arrows show one large fault, but there are other smaller ones in the picture.

Landscape features

  • Troughs to the East of Albor Tholus, as seen by HiRISE under the HiWish program.

  • Portion of a trough (Fossae) in Elysium Planitia, as seen by HiRISE under the HiWish program. Blue indicates possible seasonal frost.

Dark slope streaks

  • Layers and dark slope streaks, as seen by HiRISE under HiWish program

  • Dark slope streaks on mesa, as seen by HiRISE under HiWish program Location is Amazonis quadrangle.

  • Close-up of some layers under cap rock of a pedestal crater and a dark slope streak, as seen by HiRISE under HiWish program.

  • Dark slope streaks and layers near a pedestal crater, as seen by HiRISE under the HiWish program. Arrows show the small starting points for the streaks.

Layers

Many places on Mars show rocks arranged in layers. Rock can form layers in a variety of ways. Volcanoes, wind, or water can produce layers.[12] Layers can be hardened by the action of groundwater.

Main article: Groundwater on Mars § Layered terrain

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  • Layers exposed at the base of a group of buttes in Mangala Valles in Memnonia quadrangle, as seen by HiRISE under HiWish program. Arrows point to boulders sitting in pits. The pits may have formed by winds, heat from the boulders melting ground ice, or some other process.

  • Buttes, as seen by HiRISE under HiWish program. Buttes have layered rocks with a hard resistant cap rock on the top which protects the underlying rocks from erosion.

  • Butte in Crommelin Crater, as seen by HiRISE under HiWish program. Location is Oxia Palus quadrangle.

  • Layers in Crommelin Crater, as seen by HiRISE under HiWish program. Location is Oxia Palus quadrangle.

  • Light toned butte, as seen by HiRISE, under HiWish program. Light toned material is probably sulfate-rich and similar to material examined by Spirit Rover, and it once probably covered the whole floor.

  • Layered terrain in Aeolis quadrangle, as seen by HiRISE under HiWish program.

  • Layers in Arabia, as seen by HiRISE under HiWish program.

Gullies

Martian gullies are small, incised networks of narrow channels and their associated downslope sediment deposits, found on the planet of Mars. They are named for their resemblance to terrestrial gullies. First discovered on images from Mars Global Surveyor, they occur on steep slopes, especially on the walls of craters. Usually, each gully has a dendritic alcove at its head, a fan-shaped apron at its base, and a single thread of incised channel linking the two, giving the whole gully an hourglass shape.[13] They are believed to be relatively young because they have few, if any craters.

On the basis of their form, aspects, positions, and location amongst and apparent interaction with features thought to be rich in water ice, many researchers believed that the processes carving the gullies involve liquid water. However, this remains a topic of active research.

Main article: Martian gullies

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Image of gullies with main parts labeled. The main parts of a Martian gully are alcove, channel, and apron. Since there are no craters on this gully, it is thought to be rather young. Picture was taken by HiRISE under HiWish program. Location is Phaethontis quadrangle.

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  • Close-up of gully aprons showing they are free of craters; hence very young. Location is Phaethontis quadrangle. Picture was taken by HiRISE under HiWish program.

  • Gullies on wall of crater, as seen by HiRISE under HiWish program Location is the Mare Acidalium quadrangle.

  • Close-up of gully channels, as seen by HiRISE under HiWish program. This image shows many streamlined forms and some benches along a channel. These features suggest formation by running water. Benches are usually formed when the water level goes down a bit and stays at that level for a time. Picture was taken with HiRISE under HiWish program. Location is the Mare Acidalium quadrangle. Note this is an enlargement of a previous image.

  • Gullies in crater in Phaethontis quadrangle, as seen by HiRISE under HiWish program

Scalloped topography

Scalloped topography is common in the mid-latitudes of Mars, between 45° and 60° north and south. It is particularly prominent in the region of Utopia Planitia[14][15] in the northern hemisphere and in the region of Peneus and Amphitrites Patera[16][17] in the southern hemisphere. Such topography consists of shallow, rimless depressions with scalloped edges, commonly referred to as “scalloped depressions” or simply “scallops”. Scalloped depressions can be isolated or clustered and sometimes seem to coalesce. A typical scalloped depression displays a gentle equator-facing slope and a steeper pole-facing scarp. This topographic asymmetry is probably due to differences in insolation. Scalloped depressions are believed to form from the removal of subsurface material, possibly interstitial ice, by sublimation. This process may still be happening at present.[18]

  • Scalloped ground, as seen by HiRISE under HiWish program.

  • Close up of scalloped ground, as seen by HiRISE under HiWish program. Surface is divided into polygons; these forms are common where ground freezes and thaws. Note: this is an enlargement of a previous image.

  • Scalloped ground, as seen by HiRISE under HiWish program.

  • Close-up of scalloped ground, as seen by HiRISE under HiWish program. Surface is divided into polygons; these forms are common where ground freezes and thaws. Note: this is an enlargement of a previous image.

Ring mold craters

Ring mold craters are believed to be formed from asteroid impacts into ground that has an underlying layer of ice. The impact produces an rebound of the ice layer to form a “ring-mold” shape.

Main article: Ring mold crater

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  • Ring mold craters of various sizes on floor of a crater, as seen by HiRISE under HiWish program Location is Ismenius Lacus quadrangle.

  • Wide view of a field of ring mold craters, as seen by HiRISE under HiWish program

  • Close view of ring mold crater, as seen by HiRISE under HiWish program Note: this is an enlargement of the previous image of a field of ring mold craters.

Dust devil tracks

Dust devil tracks can be very pretty. They are caused by giant dust devils removing bright colored dust from the Martian surface; thereby exposing a dark layer.

  • Dust devil tracks, as seen by HiRISE under HiWish program.

  • Dust devil tracks, as seen by HiRISE under HiWish program

Upper Plains Unit

Remnants of a 50-100 meter thick mantling, called the upper plains unit, has been discovered in the mid-latitudes of Mars. First investigated in the Deuteronilus Mensae (Ismenius Lacus quadrangle) region, but it occurs in other places as well. The remnants consist of sets of dipping layers in craters and along mesas.[19] Sets of dipping layers may be of various sizes and shapes—some look like Aztec pyramids from Central America

  • Layered structure in crater that is probably what is left of a layered unit that once covered a much larger area. Material for this unit fell from the sky as ice-coated dust. The picture was taken by HiRISE, under the HiWish program. Picture is from Hellas quadrangle.

  • Dipping layers, as seen by HiRISE under HiWish program

  • Layered features in crater, as seen by HiRISE under HiWish program

  • Layered structures, as seen by HiRISE under HiWish program

This unit also degrades into brain terrain. Brain terrain is a region of maze-like ridges 3–5 meters high. Some ridges may consist of an ice core, so they may be sources of water for future colonists.

  • Layered features and brain terrain, as seen by HiRISE under HiWish program The upper plains unit often changes into brain terrain.

Some regions of the upper plains unit display large fractures and troughs with raised rims; such regions are called ribbed upper plains. Fractures are believed to have started with small cracks from stresses. Stress is suggested to initiate the fracture process since ribbed upper plains are common when debris aprons come together or near the edge of debris aprons—such sites would generate compressional stresses. Cracks exposed more surfaces, and consequently more ice in the material sublimates into the planet’s thin atmosphere. Eventually, small cracks become large canyons or troughs.

  • Well developed ribbed upper plains material. These start with small cracks that expand as ice sublimates from the surfaces of the crack. Picture was taken with HiRISE under HiWish program

  • Dipping layers, as seen by HiRISE under HiWish program Also, Ribbed Upper plains material is visible in the upper right of the picture. It is forming from the upper plains unit, and in turn is being eroded into brain terrain.

Small cracks often contain small pits and chains of pits; these are thought to be from sublimation (phase transition) of ice in the ground.[20][21] Large areas of the Martian surface are loaded with ice that is protected by a meters thick layer of dust and other material. However, if cracks appear, a fresh surface will expose ice to the thin atmosphere.[22][23] In a short time, the ice will disappear into the cold, thin atmosphere in a process called sublimation (phase transition). Dry ice behaves in a similar fashion on the Earth. On Mars sublimation has been observed when the Phoenix lander uncovered chunks of ice that disappeared in a few days.[24][25] In addition, HiRISE has seen fresh craters with ice at the bottom. After a time, HiRISE saw the ice deposit disappear.[26]

The upper plains unit is thought to have fallen from the sky. It drapes various surfaces, as if it fell evenly. As is the case for other mantle deposits, the upper plains unit has layers, is fine-grained, and is ice-rich. It is widespread; it does not seem to have a point source. The surface appearance of some regions of Mars is due to how this unit has degraded. It is a major cause of the surface appearance of lobate debris aprons.[21] The layering of the upper plains mantling unit and other mantling units are believed to be caused by major changes in the planet’s climate. Models predict that the obliquity or tilt of the rotational axis has varied from its present 25 degrees to maybe over 80 degrees over geological time. Periods of high tilt will cause the ice in the polar caps to be redistributed and change the amount of dust in the atmosphere.[27][28][29]

To suggest a location for HiRISE to image visit the site at http://www.uahirise.org/hiwish

See also

References

  1. ^ “Public Invited To Pick Pixels On Mars”. Mars Daily. January 22, 2010. Retrieved January 10, 2011. 
  2. ^ Interview with Alfred McEwen on Planetary Radio, 3/15/2010
  3. ^ http://www.planetary.org/multimedia/planetary-radio/show/2010/384.html
  4. ^ “NASA releases first eight “HiWish” selections of people’s choice Mars images”. TopNews. April 2, 2010. Retrieved January 10, 2011. 
  5. ^ Milliken, R., J. Mustard, D. Goldsby. 2003. Viscous flow features on the surface of Mars: Observations from high-resolution Mars Orbiter Camera (MOC) images. J. Geophys. Res. 108. doi:10.1029/2002JE002005.
  6. ^ Arfstrom, J and W. Hartmann. 2005. Martian flow features, moraine-like ridges, and gullies: Terrestrial analogs and interrelationships. Icarus 174, 321-335.
  7. ^ Hubbard B., R. Milliken, J. Kargel , A. Limaye, C. Souness . 2011. Geomorphological characterisation and interpretation of a mid-latitude glacier-like form: Hellas Planitia, Mars Icarus 211, 330–346
  8. ^ Baker, V. 1982. The Channels of Mars. Univ. of Tex. Press, Austin, TX
  9. ^ http://marsnext.jpl.nasa.gov/workshops/index.cfm
  10. ^ http://hirise.lpl.arizona.edu/ESP_039404_1820
  11. ^ Pondrelli, M., A. Rossi, L. Deit, S. van Gasselt, F. Fueten, E. Hauber, B. Cavalazzi, M. Glamoclija, and F. Franchi. 2014. A PROPOSED LANDING SITE FOR THE 2020 MARS MISSION: FIRSOFF CRATER. http://marsnext.jpl.nasa.gov/workshops/2014_05/33_Pondrelli_Firsoff_LS2020.pdf
  12. ^ “HiRISE | High Resolution Imaging Science Experiment”. Hirise.lpl.arizona.edu?psp_008437_1750. Retrieved 2012-08-04. 
  13. ^ Malin, M., Edgett, K. 2000. Evidence for recent groundwater seepage and surface runoff on Mars. Science 288, 2330–2335.
  14. ^ Lefort, A.; Russell, P. S.; Thomas, N.; McEwen, A. S.; Dundas, C. M.; Kirk, R. L. (2009). “Observations of periglacial landforms in Utopia Planitia with the High Resolution Imaging Science Experiment (HiRISE)”. Journal of Geophysical Research 114 (E4). Bibcode:2009JGRE..11404005L. doi:10.1029/2008JE003264. 
  15. ^ Morgenstern, A; Hauber, E; Reiss, D; van Gasselt, S; Grosse, G; Schirrmeister, L (2007). “Deposition and degradation of a volatile-rich layer in Utopia Planitia, and implications for climate history on Mars” (PDF). Journal of Geophysical Research – Planets 112 (E6): E06010. Bibcode:2007JGRE..11206010M. doi:10.1029/2006JE002869. 
  16. ^ Lefort, A.; Russell, P.S.; Thomas, N. (2010). “Scalloped terrains in the Peneus and Amphitrites Paterae region of Mars as observed by HiRISE”. Icarus 205 (1): 259. Bibcode:2010Icar..205..259L. doi:10.1016/j.icarus.2009.06.005. 
  17. ^ Zanetti, M.; Hiesinger, H.; Reiss, D.; Hauber, E.; Neukum, G. (2009). “Scalloped Depression Development on Malea Planum and the Southern Wall of the Hellas Basin, Mars” (PDF). Lunar and Planetary Science 40. p. 2178, abstract 2178. Bibcode:2009LPI….40.2178Z. 
  18. ^ http://hiroc.lpl.arizona.edu/images/PSP?diafotizo.php?ID=PSP_002296_1215
  19. ^ Carr, M. 2001.
  20. ^ Morgenstern, A., et al. 2007
  21. ^ a b Baker, D., J. Head. 2015. Extensive Middle Amazonian mantling of debris aprons and plains in Deuteronilus Mensae, Mars: Implication for the record of mid-latitude glaciation. Icarus: 260, 269-288.
  22. ^ Mangold, N. 2003. Geomorphic analysis of lobate debris aprons on Mars at Mars Orbiter Camera scale: Evidence for ice sublimation initiated by fractures. J. Geophys. Res. 108, 8021.
  23. ^ Levy, J. et al. 2009. Concentric
  24. ^ Bright Chunks at Phoenix Lander’s Mars Site Must Have Been Ice – Official NASA press release (19.06.2008)
  25. ^ http://www.nasa.gov/mission_pages/phoenix/news/phoenix-20080619.html
  26. ^ Byrne, S. et al. 2009. Distribution of Mid-Latitude Ground Ice on Mars from New Impact Craters: 329.1674-1676
  27. ^ Head, J. et al. 2003.
  28. ^ Madeleine, et al. 2014.
  29. ^ Schon, et al. 2009. A recent ice age on Mars: Evidence for climate oscillations from regional layering in mid-latitude mantling deposits. Geophys. Res. Lett. 36, L15202.

Recommended reading

  • Lorenz, R. 2014. The Dune Whisperers. The Planetary Report: 34, 1, 8-14
  • Lorenz, R., J. Zimbelman. 2014. Dune Worlds: How Windblown Sand Shapes Planetary Landscapes. Springer Praxis Books / Geophysical Sciences.
  • Grotzinger, J. and R. Milliken (eds.). 2012. Sedimentary Geology of Mars. SEPM.

External links