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| Titel |
Comparison of Polygonal Impact Craters on Mercury and on other Terrestrial Planets |
| VerfasserIn |
G. T. Weihs, J. J. Leitner, M. G. Firneis |
| 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 |
250061686
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| Zusammenfassung |
| The rims of a polygonal impact crater partly are composed of several straight segments.
Analyzing the images transmitted back to Earth by the spacecrafts Mariner 10 and
MESSENGER, polygonal impact craters with at least two straight rim segments, were
detected on Mercury. The search for polygonal impact craters on Mercury was carried out,
using the IAU/NASA/USGS-Planetary-Database: each of the 15 quadrangle-maps was
scanned for impact craters with at least two straight rims. In a second step the data
preparation was resulting in a set of two images per PIC, one with marked straight rims and
an original one for the purpose of comparison. The polygonal impact craters found were
documented: a total number of 33 polygonal impact craters out of 291 by IAU approved
craters, is according to our expectation of 10 to 15 % polygonal impact craters out of all
impact craters on Mercury. The polygonal impact craters’ diameters reach from 65 km to
240 km, the mean diameter is about 120 km, the same value as for all Mercury’s
impact craters. Angles between the straight rims are found in a range between 98°
and 132°. The specific morphology of polygonal impact craters on Mercury in
general is of the type of complex craters with terraced rims, which often are found on
other terrestrial planets like Mars. An assumed connection between the structure
of polygonal impact craters and the structure of the geologic environment on the
surface was not found at first sight. Several problems detecting the polygonal shape
occurred, because many of the craters are heavily degraded. Though the quality of
some of the images taken by Mariner 10 and MESSENGER is partly limited, it
was possible to detect the polygonal shapes. The study proves the existence of
polygonal impact craters on Mercury. Furthermore the assumption was confirmed, that
polygonal impact craters are an integral part of impact craters and common on
the Moon, all terrestrial planets and several asteroids and icy moons like Europa. |
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