Pollywog Craters on Mars
Pollywog Craters on Mars
ESP_061768_2200  Science Theme: Fluvial Processes
This crater is approximately 2.3 kilometers across and is located in northern Arabia Terra near where the cratered highlands meets the northern lowlands (called a “dichotomy boundary”). Small craters with an exit channel, such as this one, are nicknamed “pollywog” craters, as they resemble tadpoles.

The channel is consistent with flow *out of* the crater, rather than flow *into* the crater, because 1) the valleys do not cut down to the level of the interior crater floor, and 2) there are no deposits of material on the floor associated with the mouth of the valley.

This small crater was probably once filled with an ice-covered lake that overflowed, forming the exit channel. Young craters with exit channels are intriguing because they record a relatively recent (during the Amazonian epoch) wet environment on Mars.

Written by: Sharon Wilson  (12 February 2020)

This is a stereo pair with ESP_062045_2200.
Acquisition date
30 September 2019

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
298.1 km (185.3 miles)

Original image scale range
29.8 cm/pixel (with 1 x 1 binning) so objects ~89 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
41°, with the Sun about 49° above the horizon

Solar longitude
86.7°, Northern Spring

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  359.0°
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

Black and white
map-projected   (714MB)

IRB color
map-projected   (409MB)

Black and white
map-projected  (360MB)
non-map           (311MB)

IRB color
map projected  (134MB)
non-map           (276MB)

Merged IRB
map projected  (200MB)

Merged RGB
map-projected  (192MB)

RGB color
non map           (274MB)
Map-projected, reduced-resolution
Full resolution JP2 download
Anaglyph details page

B&W label
Color label
Merged IRB label
Merged RGB label
EDR products

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

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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.