CODEBOOK – MARS CRATER DATASET
Name: PRIYA HEGDE
Course Name: Data Analysis and Interpretation
Data Set Overview:
The Mars Global Crater Database used in this study is taken from Robbins (2011). According to this dataset, Mars contains 378,540 craters with diameters ≥ 1 km
The purpose of this study is to analyse the crater size, depth, morphology, and the surface history of the planet. The database includes a unique identification number for every crater entry.
Variables:
Variable Name
Types of variables
Description
Why included
CRATER_ID
String
Unique crater identifier
Track individual craters
LATITUDE_CIRCLE_IMAGE
Decimal degrees (°N)
Latitude of crater centre (circle-fit)
Map location and geospatial patterns
LONGITUDE_CIRCLE_IMAGE
Decimal degrees (°E)
Longitude of crater centre (circle-fit)
Map location and spatial clustering
DIAM_CIRCLE_IMAGE
Kilometres (km)
Crater diameter from circle-fit
Main research variable (crater size)
DEPTH_RIMFLOOR_TOPOG
Kilometres (km)
Rim-to-floor depth (average of selected points)
Second main variable (crater depth/erosion indicator)
NUMBER_LAYERS
Integer (0,1, 2...)
Maximum number of ejecta layers identified
Indicator of ejecta complexity / impact energy
MORPHOLOGY_EJECTA_1
Categorical (e.g., SLERC, DLERS)
Primary ejecta morphology (inner-most)
Understand ejecta type vs size
MORPHOLOGY_EJECTA_2
Categorical (HuSL, SmSL, etc.)
Morphology of ejecta layers
Secondary morphology descriptor
MORPHOLOGY_EJECTA_3
Categorical
Outer ejecta texture/shape (butterfly, pincushion)
Special ejecta patterns, unusual impacts
Research Question & Hypothesis:
Research question:
Is crater diameter on Mars associated with crater depth?
Is crater diameter on Mars associated ejecta complexity?
Hypothesis: Larger craters (higher DIAM_CIRCLE_IMAGE) will have greater depth (DEPTH_RIMFLOOR_TOPOG) and more ejecta layers (NUMBER_LAYERS) and more complex ejecta morphology (MORPHOLOGY_EJECTA_1).
References Identified:
Robbins, S. J. (2011). Planetary Surface Properties from a Global Martian Crater Database.
Garvin, J. (2003). Global Geometric Properties of Mars Impact Craters.
Melosh, H. (1989). Impact Cratering: A Geologic Process.
Watters, T. (2015). Impact Craters and Surface Ages on Mars.
KEY POINTS:
Robbins (2011) developed a comprehensive global database of Martian craters, including detailed measurements of crater diameter, depth, and ejecta characteristics.
Garvin (2003) and Watters (2015) demonstrated a positive correlation between crater diameter and depth, although depth variability arises from erosional and depositional processes.
Melosh (1989) provided the theoretical framework linking impact energy to crater size and ejecta morphology complexity.
Collectively, these studies support the hypothesis that larger craters exhibit greater depth and more complex ejecta structures.