Featured Image - 04/07/2009
The Fra Mauro Formation
This stunning oblique Apollo Metric photograph shows the Apollo 14
landing site explored by Alan Shepard and Edgar Mitchell in January
1971 as viewed from the Apollo 16 Command Service Module Casper
in April 1972. The rough, craggy looking materials you can see in the
center of the frame are the Fra Mauro formation, named after nearby
Fra Mauro crater. The Fra Mauro formation is ejecta from the Imbrium
basin-forming event, which is just over the horizon to the north
Figure 1. Annotated Apollo 16 Metric Mapping
Camera frame showing the Fra Mauro formation south of the Imbrium
basin (Apollo Image AS16-M-1420 [NASA/JSC/Arizona State
The Fra Mauro site was one of only two highlands sites to be visited
during Project Apollo, and the samples collected at the Apollo 14
landing site continue to provide lunar scientists with important
insights into the geology of the lunar highlands. Nearly all of the
Apollo 14 samples are breccias (or rocks formed from pieces of other
rocks, often held together by an impact-melt matrix). Breccias were
also found later to be the primary rock type at the Apollo 16 landing
site, and consequently are now known to be ubiquitous in the lunar
highlands. Since the Fra Mauro formation is ejecta from the Imbrium
basin-forming event, age-dating the samples returned by Shepard and
Mitchell in terrestrial laboratories indicated that the Imbrium basin
formed approximately 3.85 billion years ago, providing a crucial
absolute age date for the formation of the Imbrium basin, a crucial
event in the lunar geologic timescale.
Despite the momentous discoveries made by the Apollo 14 and Apollo 16
crews, there is still much we do not know about the lunar highlands.
In particular, lunar scientists are eager to use the remote sensing
data returned by the Lunar
Reconnaissance Orbiter and other ongoing lunar missions like
Kaguya and Chandrayaan-1 to look for evidence of highlands rock types
which may be underrepresented in the current Apollo sample collection.
Since we only explored two locations in the lunar highlands during
Apollo, it is possible that there are lunar highlands rock types which
have not yet been sampled. By identifying the location of any
under-sampled rock types on the lunar surface using orbital data, the
scientific results obtained by these new lunar scouts will help to
determine the places on the Moon where we need to send future human explorers.
For more information:
14 Sample Overview at the Lunar and Planetary Institute
Over the Moon: A View From Orbit (1978) H. Masursky, G. W. Colton,
F. El-Baz, eds. NASA SP-362.
Wilhelms, Don E. (1987) The Geologic History of the Moon,
U. S. Geological Survey Professional Paper 1348.