Why not a constant early lunar impact rate?
Two distinct episodes of impacting are recorded on the Moon's surface. An early episode marked by an intense barrage that included basin-forming projectiles ended about 3.8 aeons ago when the Orientale basin was created. The second episode, after 3.2 or 3.3 aeons ago, was marked by a much lower...
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ftnasantrs:oai:casi.ntrs.nasa.gov:19850015225 2023-05-15T18:22:34+02:00 Why not a constant early lunar impact rate? Wilhelms, D. E. Unclassified, Unlimited, Publicly available Apr 1, 1985 http://ntrs.nasa.gov/search.jsp?R=19850015225 unknown http://ntrs.nasa.gov/search.jsp?R=19850015225 Accession ID: 85N23536 No Copyright Other Sources 91 NASA, Washington Repts. of Planetary Geol. and Geophys. program, 1984; p 174-176 1985 ftnasantrs 2012-02-15T16:06:03Z Two distinct episodes of impacting are recorded on the Moon's surface. An early episode marked by an intense barrage that included basin-forming projectiles ended about 3.8 aeons ago when the Orientale basin was created. The second episode, after 3.2 or 3.3 aeons ago, was marked by a much lower impact rate. These very different rates are separated by a short transition period during the Late Imbrian Epoch. It is found that a constant preImbrian impact rate is consistent with all the relevant observations and with the following lunar historical scenario: (1) crustal solidification between about 4.3 and 4.25 aeons ago; (2) formation of Procellarum, South Pole-Aitken, about 22 now-obliterated basins, and about 2,850 now-obliterated 30 to 300 km craters between 4.25 and 4.1 aeons ago; and (3) formation of 39 still-preserved basins, 1,200 still-perserved craters, and 2,200 now-obliterated craters between 4.1 and 3.85 aeons ago. At the constant rate, the amount of mass that impacted the Moon since crustal solidification would not greatly exceed the amount that has left a permanent visible record. Other/Unknown Material South pole NASA Technical Reports Server (NTRS) Aitken ENVELOPE(-44.516,-44.516,-60.733,-60.733) South Pole |
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Open Polar |
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NASA Technical Reports Server (NTRS) |
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ftnasantrs |
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91 |
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91 Wilhelms, D. E. Why not a constant early lunar impact rate? |
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91 |
description |
Two distinct episodes of impacting are recorded on the Moon's surface. An early episode marked by an intense barrage that included basin-forming projectiles ended about 3.8 aeons ago when the Orientale basin was created. The second episode, after 3.2 or 3.3 aeons ago, was marked by a much lower impact rate. These very different rates are separated by a short transition period during the Late Imbrian Epoch. It is found that a constant preImbrian impact rate is consistent with all the relevant observations and with the following lunar historical scenario: (1) crustal solidification between about 4.3 and 4.25 aeons ago; (2) formation of Procellarum, South Pole-Aitken, about 22 now-obliterated basins, and about 2,850 now-obliterated 30 to 300 km craters between 4.25 and 4.1 aeons ago; and (3) formation of 39 still-preserved basins, 1,200 still-perserved craters, and 2,200 now-obliterated craters between 4.1 and 3.85 aeons ago. At the constant rate, the amount of mass that impacted the Moon since crustal solidification would not greatly exceed the amount that has left a permanent visible record. |
format |
Other/Unknown Material |
author |
Wilhelms, D. E. |
author_facet |
Wilhelms, D. E. |
author_sort |
Wilhelms, D. E. |
title |
Why not a constant early lunar impact rate? |
title_short |
Why not a constant early lunar impact rate? |
title_full |
Why not a constant early lunar impact rate? |
title_fullStr |
Why not a constant early lunar impact rate? |
title_full_unstemmed |
Why not a constant early lunar impact rate? |
title_sort |
why not a constant early lunar impact rate? |
publishDate |
1985 |
url |
http://ntrs.nasa.gov/search.jsp?R=19850015225 |
op_coverage |
Unclassified, Unlimited, Publicly available |
long_lat |
ENVELOPE(-44.516,-44.516,-60.733,-60.733) |
geographic |
Aitken South Pole |
geographic_facet |
Aitken South Pole |
genre |
South pole |
genre_facet |
South pole |
op_source |
Other Sources |
op_relation |
http://ntrs.nasa.gov/search.jsp?R=19850015225 Accession ID: 85N23536 |
op_rights |
No Copyright |
_version_ |
1766201977242386432 |