Optical maturity of ejecta from large rayed lunar craters

Jennifer A. Grier, Alfred S. McEwen, Paul G. Lucey, Moses Milazzo, Robert G. Strom

Research output: Contribution to journalArticle

73 Citations (Scopus)

Abstract

Lucey et al. [2000] have developed a methodology for extracting an optical maturity parameter (OMAT) from multispectral Clementine images. The OMAT parameter characterizes the overall maturity of lunar soils and crater ejecta by changes in reflectance spectra. Using these OMAT images, we surveyed large craters (≥20 km diameter) on the Moon that had previously been mapped as possessing or possibly possessing rayed ejecta. We generated average radial profiles of OMAT values for rays of these large craters. From these profiles we classified the craters into three relative age groups: (1) older than Copernicus (inferred age of ∼810 Myr), (2) intermediate, and (3) as young or younger than Tycho (inferred age of ∼109 Myr). We suspect that there is a bias to our classification scheme, such that the OMAT profiles of smaller craters look like that of larger but older craters. Nevertheless, some large craters, such as Eudoxus (67 km) and Aristillus (55 km), are now known from this study to have optically mature ejecta and therefore are suspected to be older than Copernicus (this is consistent with an age of 1.3 Gyr suggested for Aristillus by Ryder et al. [1991]). Such craters were included by McEwen et al. [1997] when estimating the density of craters younger than or contemporaneous with Copernicus. Therefore the case for a modest increase in the cratering rate (in the past 800 Myr versus the previous 2.4 Gyr) indicated from that work has been weakened [Grier and McEwen, 2001]. Given current constraints on dating large and recent lunar craters, we cannot support (or disprove) the hypothesis that there has been a significant increase in the rate of large terrestrial impact events in the past 100-400 Myr.

Original languageEnglish (US)
Pages (from-to)32847-32862
Number of pages16
JournalJournal of Geophysical Research: Space Physics
Volume106
Issue numberE12
StatePublished - Dec 25 2001

Fingerprint

lunar craters
Moon
ejecta
craters
crater
Soils
profiles
lunar soil
cratering
moon
dating
multispectral image
rays
estimating
methodology
parameter
reflectance

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Atmospheric Science
  • Geochemistry and Petrology
  • Geophysics
  • Oceanography
  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Grier, J. A., McEwen, A. S., Lucey, P. G., Milazzo, M., & Strom, R. G. (2001). Optical maturity of ejecta from large rayed lunar craters. Journal of Geophysical Research: Space Physics, 106(E12), 32847-32862.

Optical maturity of ejecta from large rayed lunar craters. / Grier, Jennifer A.; McEwen, Alfred S.; Lucey, Paul G.; Milazzo, Moses; Strom, Robert G.

In: Journal of Geophysical Research: Space Physics, Vol. 106, No. E12, 25.12.2001, p. 32847-32862.

Research output: Contribution to journalArticle

Grier, JA, McEwen, AS, Lucey, PG, Milazzo, M & Strom, RG 2001, 'Optical maturity of ejecta from large rayed lunar craters', Journal of Geophysical Research: Space Physics, vol. 106, no. E12, pp. 32847-32862.
Grier JA, McEwen AS, Lucey PG, Milazzo M, Strom RG. Optical maturity of ejecta from large rayed lunar craters. Journal of Geophysical Research: Space Physics. 2001 Dec 25;106(E12):32847-32862.
Grier, Jennifer A. ; McEwen, Alfred S. ; Lucey, Paul G. ; Milazzo, Moses ; Strom, Robert G. / Optical maturity of ejecta from large rayed lunar craters. In: Journal of Geophysical Research: Space Physics. 2001 ; Vol. 106, No. E12. pp. 32847-32862.
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