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Apollo 17: Exploration at Taurus-Littrow
The Apollo 17 Lunar Module is scheduled to land Dec. 11 in the Taurus-Littrow
region of the Moon for the last mission in the Apollo series. The site
is in the Highlands that form the eastern mountainous rim of Mare Serenitatis,
one of the Moons largest multi-ringed basins. The bulk of these
highlands is believed to consist of brecciated lunar crustal material
uplifted at the time of formation of the Serenitatis basin, although ejecta
from younger large basins such as Imbrium and mantling volcanic materials
may also be present.
Major objectives of the mission are to investigate and sample 1) highlands,
which should provide samples of some of the oldest rocks to be collected
on the Moon, 2) basin-filling materials, exposed in the walls of some
of the larger craters near the landing point, and 3) dark mantle
possibly of volcanic origin that may be one of the youngest units
on the Moons surface.
The landing point (20o0950.5N; 30o4458.3E) is
in a steep-walled, flat-floored valley that is more than 2 kilometers
deep. The valley is interpreted as a graben formed in highlands materials
during the Serenitatis event. A subsequently deposited basin-filling unit
is thought to have largely buried and leveled an initially irregular surface
of the graben. A presumably very young and fine-grained, dark mantling
deposit, possibly pyroclastic, veneers much of the uplands area and blankets
the valley floor.
The geology of this area is the most complex of the Apollo landing sites.
Fortunately, Apollo 15 panoramic and metric-camera [orbital] photography
enables us to study the site at a level of detail not possible in earlier
missions. Using an analytical stereoplotter, we obtained resolution of
about 2 meters, as compared with 15 or 20 meters for pre-mission photography
for Apollos 15 and 16.
activity (preliminary plans). A total of 75 hours is
to be spent on the lunar surface, including three 7-hour EVAs (extravehicular
activities). EVA-1 will be largely occupied in setting up the lunar roving
vehicle (LRV), Apollo lunar surface experiments package (ALSEP), surface
electrical properties (SEP) antenna, and other experiments, with about
2 hours available for a traverse. ...
On EVA 1 traverse, the astronauts will investigate the subfloor and local
dark mantle units. EVA 2 is to be devoted mainly to the South Massif and
its avalanche deposit. The principal goals of EVA 3 are sampling of the
North Massif and sculptured hills. Subfloor samples will be obtained from
several large craters in the plains. The dark mantle may be derived from
a large number of local sources.
Additional samples will be collected
between stations by the LRV sampler, a long-handled tool designed for
collecting soil or small rocks from the rover.
Three experiments in traverse geophysics are planned in order to complement
the geological studies of the subfloor and dark mantle. In the SEP experiment,
a receiver mounted on the LRV will continuously record electromagnetic
data transmitted from the SEP antenna during the EVA 2 and 3 traverses.
Eight explosive charges for the seismic-profiling experiment will be deployed
on the plains during the traverses and detonated after the crew has left
the Moon. Seismic waves from the explosions will be detected by a geophone
array at the ALSEP site. A gravity measurement will be made at each traverse
station and at the LM and ALSEP sites.
By Edward W. Wolfe, Val L. Freeman and William
Muehlberger (principal investigator), of the U.S. Geological Survey, Flagstaff,
Ariz.; James W. Head of Bell Telephone Laboratories, Washington, D.C.;
and Harrison H. Schmitt (of the Apollo 17 crew) and John R. Sevier, both
of the Manned Spacecraft Center, Houston.
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