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Crater ages

Chosen by "type" in ages.

Type What it is
uniform Ages uniform over one lifetime for every diameter, so freshness is uniform between 0 and 1.
fresh Every crater is fresh, with age and lifetime zero.
steady_state Crater ages where small craters are in equilibrium: a crater lasts until the production rate replaces the equilibrium density, or the surface's age, with ages drawn from the chronology's formation rate.

uniform

Ages uniform over one lifetime for every diameter, so freshness is uniform between 0 and 1.

Key Type Default Range Unit Description
lifetime_gyr number 1.0 (0, inf) Gyr Lifetime in Gyr, positive, that every crater's age is drawn uniformly within; with degradation, a crater this old is fully worn.
Every key with its default 
{
    "type": "uniform",
    "lifetime_gyr": 1.0
}

Used in: example_ages_uniform, example_planets_mars_bedforms, example_planets_mars_craters, example_planets_mercury_site

fresh

Every crater is fresh, with age and lifetime zero.

Every key with its default 
{
    "type": "fresh"
}

Used in: example_ages_fresh, example_albedo_rocks_and_slopes

steady_state

Crater ages where small craters are in equilibrium: a crater lasts until the production rate replaces the equilibrium density, or the surface's age, with ages drawn from the chronology's formation rate.

Key Type Default Range Unit Description
age_gyr number 3.5 [0, 4.6] Gyr Age of the surface in Gyr, from 0 to 4.6; it caps every crater's lifetime, so larger craters on an older surface can be older.
production one of neukum, extended_neukum, ivanov "extended_neukum" Production function whose rate, with the equilibrium, sets how long small craters last.
equilibrium one of trask, hartmann "trask" Equilibrium density that, with the production rate, sets how long small craters last before they are erased.
chronology one of neukum, ivanov "neukum" Chronology whose formation rate the craters' ages are drawn from.
Every key with its default 
{
    "type": "steady_state",
    "age_gyr": 3.5,
    "production": "extended_neukum",
    "equilibrium": "trask",
    "chronology": "neukum"
}

Used in: example_ages_steady_state, example_albedo_blast_zone, example_albedo_crater_rays, example_albedo_fresh_crater, example_albedo_moon_site, example_albedo_new_crater, example_albedo_oblique_rays, example_boulders_layer and 15 more