Distal Rampart of Crater in Chryse Planitia
Distal Rampart of Crater in Chryse Planitia
ESP_014417_1975  Science Theme: Impact Processes
Impact craters on Mars are kind of neat: many of them look very different than impact craters seen on the Moon or Mercury.

Fresh lunar and Mercurian craters have ejecta blankets that look a bit rough near the crater rims; around larger craters, long rays or chains of secondary craters radiate away from the crater rims. Some Martian craters are similar to these craters, but Mars also has a high proportion of craters with forms not found on the Moon or Mercury: rampart craters.

Rampart craters, also called fluidized-ejecta craters, have ejecta blankets that appear lobate, or rounded, and end in low ridges or ramparts, such as the ridge in this HiRISE image. Here you see the rampart at the edge of the ejecta blanket that comes from an approximately 16 kilometer (10 mile)-diameter crater, about 16 km (10 mi) to the east.

For years there has been a debate about whether these lobes and ramparts were formed by ejecta interacting with the thin Martian atmosphere, or whether they formed because volatiles (such as water or ice) in the subsurface were incorporated into the ejecta material excavated by the impact. The common consensus is now in favor of the volatile hypothesis. Because of this, rampart craters can be used to indicate the past presence of water or ice in the Martian crust.

Written by: Andrea Philippoff  (12 November 2009)

This is a stereo pair with ESP_014140_1975.
Acquisition date
23 August 2009

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
280.9 km (174.6 miles)

Original image scale range
60.3 cm/pixel (with 2 x 2 binning) so objects ~181 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
46°, with the Sun about 44° above the horizon

Solar longitude
326.4°, Northern Winter

For non-map projected images
North azimuth:  96°
Sub-solar azimuth:  324.0°
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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.