Chain Gang
Chain Gang
ESP_020280_2000  Science Theme: Impact Processes
This chain of secondary craters just happened to be well-aligned with HiRISE's groundtrack (the path across the surface that a spot directly below the MRO spacecraft would trace out). Because of this favorable alignment, HiRISE was able to capture most of the chain in one 25 kilometer-long (15.6 mile) image.

Secondary craters occur during the formation of an impact crater. Impacts are very high-energy events, and while some rock gets melted or vaporized, other rock gets broken into large chunks and flung outward from the crater. Some of these pieces have enough energy to form small craters themselves when they reimpact the surface of Mars.

These craters can be of the same diameter as primary craters (those created directly from bodies entering the Martian atmosphere from space). In addition, primary crater clusters also exist (see examples like PSP_010200_1805, PSP_010292_1785, and ESP_017270_2265), leading to difficulties in determining the process responsible for creating a particular group of craters. One distinguishing feature of secondary craters is that they tend to be irregularly shaped, due to the lower velocity of crater ejecta.

Written by: Nicole Baugh  (4 January 2011)
Acquisition date
23 November 2010

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
281.8 km (175.2 miles)

Original image scale range
56.4 cm/pixel (with 2 x 2 binning) so objects ~169 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
58°, with the Sun about 32° above the horizon

Solar longitude
186.3°, Northern Autumn

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  349.4°
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   (457MB)

IRB color
map-projected   (211MB)

Black and white
map-projected  (231MB)
non-map           (246MB)

IRB color
map projected  (109MB)
non-map           (206MB)

Merged IRB
map projected  (436MB)

Merged RGB
map-projected  (405MB)

RGB color
non map           (195MB)
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

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’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.