Gullies in Sisyphi Planum
NASA/JPL/University of Arizona
Gullies in Sisyphi Planum
PSP_004804_1105  Science Theme: Glacial/Periglacial Processes
twitter  •  tumblr

WALLPAPER
800
1024
1152
1280
1440
1600
1920
2048
2560

HIFLYER
PDF (11 x 17)


Image PSP_004804_1105 shows the walls of a large pit inside Lyell Crater, near the south polar region.

This image was acquired during a period of elevated atmospheric dust, following a series of dust storms that encircled the planet; this is the cause of the longitudinal bands of contrasting gray levels in the image. We can still see through the thick atmosphere, though, gullies and other subtle features which could have been produced by water and ice present at or near the surface.

The gullies shown in the subimage (approximately 650 x 1000 meters or 710 x 1100 yards; 2618 x 4009 pixels, 11MB) have well developed alcoves, deeply incised channels, and large depositional fans, and are similar to terrestrial landscapes sculpted by surficial water.

The gullies shown in the subimage experienced several periods of activity, as evidenced by older channels cut by younger ones or by their deposits. The current and recent Martian temperatures and atmospheric conditions would not allow for water to be stable at the surface for extended periods of time: it is so cold that the water would freeze, and then it would sublime quickly, because the air is very thin and dry. These gullies could have formed under a different climate, or maybe by repeated bursts of transient fluids. Current leading hypotheses explaining the origin of gullies includes erosion from seepage or eruption of water from a subsurface aquifer, melting of ground ice, or dust-blanketed surface snow.

The otherwise subdued surface in this region is criss-crossed by numerous fissures, forming polygons some 10 meters (11 yards) across. Similar features in both shape and scale can be found in terrestrial periglacial regions such as Antarctica, where ice is present at or near the surface. Antarctica's features are the product of repeated expansion and contraction of the soil-ice mixture due to seasonal temperature oscillations. This results in polygonal networks of stress fractures.Written by: Sara Martinez-Alonso  (15 August 2007)
 
Acquisition date
05 August 2007

Local Mars time
14:56

Latitude (centered)
-69.287°

Longitude (East)
345.243°

Spacecraft altitude
250.8 km (155.9 miles)

Original image scale range
25.1 cm/pixel (with 1 x 1 binning) so objects ~75 cm across are resolved

Map projected scale
25 cm/pixel

Map projection
Polarstereographic

Emission angle
1.8°

Phase angle
54.0°

Solar incidence angle
53°, with the Sun about 37° above the horizon

Solar longitude
290.1°, Northern Winter

For non-map projected images
North azimuth:  99°
Sub-solar azimuth:  44.4°
JPEG
Black and white
map projected  non-map

IRB color
map projected  non-map

Merged IRB
map projected

Merged RGB
map projected

RGB color
non-map projected

JP2
Black and white
map-projected   (1358MB)

IRB color
map-projected   (503MB)

JP2 EXTRAS
Black and white
map-projected  (715MB)
non-map           (753MB)

IRB color
map projected  (420MB)
non-map           (730MB)

Merged IRB
map projected  (352MB)

Merged RGB
map-projected  (344MB)

RGB color
non map           (741MB)
ADDITIONAL INFORMATION
B&W label
Color label
Merged IRB label
Merged RGB label
EDR products
HiView

NB
IRB: infrared-red-blue
RGB: red-green-blue
About color products (PDF)

Black & white is 5 km across; enhanced color about 1 km
For scale, use JPEG/JP2 black & white map-projected images

USAGE POLICY
All of the images produced by HiRISE and accessible on this site are within the public domain: there are no restrictions on their usage by anyone in the public, including news or science organizations. We do ask for a credit line where possible:
NASA/JPL/University of Arizona

POSTSCRIPT
NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.