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| Titel |
A Lunar-like Chronology Model as the Mass-influx Estimator for the Inner Solar System |
| VerfasserIn |
O. Hartmann, S. C. Werner, B. A. Ivanov, G. Neukum |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250065471
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| Zusammenfassung |
| In this work will test one of the most elementary and straightforward hypothesis: What if
the early highly populated Asteroid Belt (AB) is the main source for the masses
impacted in the inner solar system, not only now, but also before 3.0Â Ga. The
model is tested by computing and comparing available impactor masses with masses
needed to create all impact craters on the terrestrial planets. Analysis of the lunar
impact-crater record and correlation of the crater size-frequency distribution (SFD)
and with isotope ages of lunar rocks, lead to a chronology model for the Moon
derived by Bloch et al., 1971, Neukum and Ivanov, 1994, Ivanov et al., 2001a. The
chronology model suggests an exponential decline of mass influx since 4.5Â Ga, and
turning into a assumed steady flux from ~ 3.0Â Ga henceforth (Neukum and Ivanov,
1994, Hartmann et al., 2007). As the AB is widely accepted as the primary source
of projectiles at least for the inner solar system, its primordial total mass and the
time-dependency of the mass flux caused by its depletion is still controversially discussed.
In this work, by mapping the crater record of each planetary body via a suitable
scaling law into hypothetical projectile masses, the total mass is estimated from the
chronology and derived projectile distributions. We compare also our results with recent
mass estimates of the AB using different dynamical collision efficiencies and other
estimate methods. As the total impact masses are highly dependent on the estimated
physical properties of the target and assumed, preliminary impact velocities of the
impactors, the mass contribution of very large basin-forming impactors dominate the
total mass balance. The method used in this approach by approximating the SFD
piecewise, contains a large error towards high mass contributions. We will present new
results based on a preliminary, extended lunar SFD polynomial for up to crater
diameters of Dmax = 1250Â km and possibly beyond, to overcome this restriction. |
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