• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.333-336
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• 2007

SELENE, a Japanese lunar mission, has been launched this year. There are large volumes of images that were already archived and will be archived by missions such as SELENE. Automatic image analysis systems, which extract useful information from large amounts of data, are now required. The authors propose Lunar Surface GIS, which archives lunar surface information collected by lunar orbiting spacecraft and conducts geological analysis automatically. This system includes automatic crater detection, automatic age determination, and lava thickness estimation methods. In this paper, methods for automatically determining the age and estimating the lava thickness of lunar mare are described. The lunar surface age was determined by analyzing data of detected crater size and number using a crater chronology method. Lava thickness was estimated by the extent of the overlying material around the crater as well as the composition of underlying terrain units. In this result, the age map at Mare Crisium suggests the mare had been formed 3.0-3.7 b.y. ago. The lava thickness result suggests the thickest part of the mare is distributed around the center of the mare. The Lunar Surface GIS can produce a geological map, age map, and mare lava thickness map, for example.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.85-85
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• 2003

We examined the hypothesis that the crater formation rate exhibits periodicity, employing data sets of Grieve (1991), Moon et al. (2001), and the Earth Impact Database (2002; DB02). DB02 is known to supercede previous compilations in terms of its accuracy and precision of the ages; it is the first time that this database has been used for periodicity analysis. For data sets comprising impact structures with D$\geq$5km (and also those with $\geq$20km), there is no convincing evidence for periodicities in the crater ages, according to our Fourier analysis. However, we detected two peaks at 16.1Myr and 34.7Myr for craters with D$\geq$30km; we confirm that the age distribution of impact craters with D$\geq$45km has dominant power at 16.1Myr. Thus, we may conjecture a probable periodic shower of Earth impactors with sizes d$\geq$1.5km. In addition, we found that the selection of data sets, the lower limits on the ages and diameters of impact craters, as well as the accuracy and precision of the ages, all constitute crucial factors in reconstructing the impact cratering history of the Earth.

• Journal of Astronomy and Space Sciences
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• v.20 no.4
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• pp.269-282
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• 2003

We examined the hypothesis that the crater formation rate exhibits periodicity, employing data sets of Grieve (1991), Moon et al. (2001), and the Earth Impact Database(2002; DB02). DB02 is known to supercede previous compilations in terms of its accuracy and precision of the ages; it is the first time that this database has been used for periodicity analysis. For data sets comprising impact structures with $D{\geq}5km$(and also those with $D{\geq}20km$), there is no convincing evidence for periodicities in the crater ages, according to our Fourier analysis. However, we detected two peaks at 16.1Myr and 34.7Myr for craters with $D{\geq}30km$; we confirm that the age distribution of impact craters with $D{\geq}45km$ has dominant power at 16.1Myr. Thus, we may conjecture a probable periodic shower of Earth impactors with sizes $d{\geq}1.5km$. In addition, we found that the selection of data sets, the lower limits on the ages and diameters of impact craters, as well as the accuracy and precision of the ages, all constitute crucial factors in reconstructing the impact cratering history of the Earth.