r.crater - GRASS GIS manual

Note: This document is for an older version of GRASS GIS that will be discontinued soon. You should upgrade, and read the current manual page.

NAME

r.crater - Creates meteorites from craters (-c) or craters from meteorites (default).

KEYWORDS

raster, planetary, impact, meteorite, crater

SYNOPSIS

r.crater

r.crater --help

r.crater [-ctgy] impactor_velocity=name impactor_angle=name target_density=name gravity_acceleration=name target_type=name impactor_density=name [projectile_diameter=name] [transient_crater_diameter=name] [final_crater_diameter=name] output=name [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags:

-c: Estimate crater diameter from projectile size [m]
-t: output the time of crater formation for Pi scaling [s]
-g: use the Gault instead of default Pi scaling
-y: use the Yield instead of default Pi scaling
--overwrite: Allow output files to overwrite existing files
--help: Print usage summary
--verbose: Verbose module output
--quiet: Quiet module output
--ui: Force launching GUI dialog

Parameters:

impactor_velocity=name [required]: Name of impactor velocity raster map [km/s]
impactor_angle=name [required]: Name of impactor angle raster map [dd.ddd]
target_density=name [required]: Name of target density raster map [kg/m^3]
gravity_acceleration=name [required]: Name of gravity acceleration raster map [m/s^-2]
target_type=name [required]: Name of target type raster map [1=liq.H2O, 2=Loose Sand, 3=Competent Rock/Saturated Soil]
impactor_density=name [required]: Name of impactor density raster map [kg/m^3]
projectile_diameter=name: Flag -c: Name of projectile diameter raster map [m]
transient_crater_diameter=name: Default mode: Name of transient crater diameter raster map [m]
final_crater_diameter=name: Default mode: Name of final crater diameter raster map [m]
output=name [required]: Name for projectile size (default) or crater size (-c) or crater creation time (-t) raster map [m] or [s]

DESCRIPTION
NOTES
NOTES
SEE ALSO
AUTHOR

DESCRIPTION

r.crater This program estimates the size of a gravity dominated impact crater or the projectile that made it.

Forward mode This mode needs to know the projectile details
L: projectile diameter (m)
r_proj: projectile density (kg/m^3)
Vi: Projectile velocity (km/s)
theta: projectile impact angle (degrees) for Gault scaling law (flag2)
Solid_rock or not (1 or 0) for Gault scaling law (flag2)

Backward modeThis mode needs to know the crater details

NOTES

Gault scaling law saturates at craters 1000 Diameter Apparent Transient, and was essentially designed for regolith (Moon surface).

Below is explanation from the Meloch Fortran code (not included because of copyright)

Three different estimates are presented, but the pi-scaling method is currently considered the best!

Impact conditions: argv[1]: enter the impact velocity in km/sec argv[2]: enter the impact angle in degrees

Target descriptors: argv[3]: enter the target density in kg/m^3 argv[4]: enter the acceleration of gravity in m/sec^2

argv[5]: enter the target type, (1-3): type 1 = liquid water type 2 = loose sand type 3 = competent rock or saturated soil argv[6]: enter the projectile density in kg/m^3

argv[7]: enter the type of computation desired (1 or 2): Mode 1, crater size Mode 2, projectile size

Mode 1: Estimate crater diameter from projectile size Mode 1 case: Projectile descriptors: argv[8]: enter the projectile diameter in m

Mode 2: Estimate crater size from crater diameter*/ Mode 2 case: Crater descriptor: argv[8]: enter the transient crater diameter in m (if the final, not the transient crater diameter is known, enter zero (0.0) here) argv[9]: [optional] enter the final crater diameter in m