Geology Reference
In-Depth Information
Figure 4.7. Photographs
showing rock fragments,
sorted by size, that
resulted from a single
impact by a small ball-
bearing projectile into a
block of solid basalt
(courtesy of Don Gault,
NASA-Ames Research
Center).
planetary geoscience, the Lunar (and Planetary) Science
Conference (LPSC), held in Houston, Texas. The purpose
of the
first meeting, held in 1970, was for the science teams
working on the Apollo samples to share their
findings with
each other and the public. In subsequent years, the confer-
ence was expanded to include all solid-surface planetary
objects. Among the many surprises revealed in the Apollo
11 samples were the great ages of the mare basalts.
Although they had been considered to be geologically
young because of the paucity of superposed impact craters,
the lavas were found to exceed 3 Ga in age. However, it
should also be noted that, well before the return of samples,
planetary scientist Bill Hartman had predicted an age of 3.6
Ga for lunar mare regions on the basis of his crater counts
and estimates of the rate of impacts.
4.2.3 Post-Apollo exploration
Following the successes of Apollo and the Soviet programs
(and the brief
flyby of Mariner 10 in 1973 on the way to
Mercury), analysis of lunar samples and other data contin-
ued, and the understanding of the Moon began to mature,
including the formulation of the now widely accepted
hypothesis of its origin. However, it would be more than
14 years until the next spacecraft would encounter the
Moon. Although not designed or intended to collect data
