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Eugene M. Shoemaker (1928-1997)
Forwarded from Brian Marsden
EUGENE M. SHOEMAKER (1928-1997)
Gene Shoemaker, renowned both as a geologist and an astronomer,
and a member of the Board of Directors of The Spaceguard Foundation, was
killed instantly on the afternoon of July 18, when his car collided head-on
with another vehicle on an unpaved road in the Tanami Desert northwest of
Alice Springs, in the Northern Territory of Australia. His wife Carolyn,
who had closely collaborated with him in both his geological and his
astronomical activities for many years, was injured in the accident
and is in stable condition in Alice Springs Hospital.
Born in Los Angeles, California, on 1928 April 28, Eugene Merle
Shoemaker graduated from the California Institute of Technology in Pasadena
at the age of 19. A thesis on the petrology of Precambrian metamorphic
rocks earned him a master's degree only a year later, at which point he joined
the United States Geological Survey, an organization with which he remained
at least partly associated for the rest of his life. His first work
for the USGS involved searching for uranium deposits in Colorado and Utah.
While doing this, he also became interested in the moon, the possibility of
traveling there, and of establishing the relative roles of asteroidal impacts
and volcanic eruptions in forming the lunar craters. He then embarked on work
for a Ph.D. at Princeton University, intending to continue his study of
metamorphic petrology, although this was interrupted when the USGS again sent
him to the field, this time leading him to an investigation of volcanic
processes, for it was in the eroded vents of ancient volcanoes that
the uranium deposits were often located.
Gene Shoemaker and Carolyn Spellman were married in 1951. A visit to
Arizona's Meteor Crater the following year began to set Gene toward the
view that both it and the lunar craters were due to asteroidal impacts. In
1956 he tried to interest the USGS in the construction of a geological
map of the moon. This work was sidelined, because the national interest
in the production of plutonium led him to study of the craters formed in small
nuclear explosions under the Yucca Flats in Nevada and invited a comparison
with Meteor Crater. It was then that he did his seminal research on the
mechanics of meteorite impacts that included the discovery, with Edward Chao,
of coesite, a type of silica produced in a violent impact. Awarded a master's
degree in 1954, Gene Shoemaker received his doctorate from Princeton in 1960
with a thesis on Meteor Crater.
In 1961 he took a leading role in the USGS venture, in Flagstaff,
Arizona, into the study of "astrogeology", the Ranger missions to the moon
and the training of the astronauts. It had long been Gene's dream to go to
the moon himself, but in 1963 he was diagnosed as having Addison's disease,
a condition that prevented him from becoming an astronaut. When the
USGS Center of Astrogeology was founded in Flagstaff in 1965, he was
appointed its chief scientist and organized the geological activities planned
for the lunar landings. In 1969 he returned to Caltech as a professor of
geology and served for three years as chairman of the Division of Geological
and Planetary Sciences there. Until he retired from the professorship in 1985
he divided his time between Pasadena and Flagstaff. He continued to maintain
an office in the USGS Astrogeology building after his formal retirement in
1993, while at the same time taking up a position at the Lowell Observatory.
It was shortly after the 1969 arrival in Pasadena that he became
interested in extending his geological knowledge of the formation and
distribution of terrestrial and lunar impact craters to the study of the
astronomical objects that formed them. With Eleanor Helin he developed a plan
to search for such objects--the Apollo asteroids--with the 0.46-m Schmidt
telescope at Palomar. This search program had its first success in July 1973
and was soon, with the help also of a number of students and of collaborations
using other Schmidt telescopes, significantly augmenting the rather meager
knowledge that had been accrued on these objects during the previous four
decades.
Carolyn became involved with measuring images from the Palomar films
in 1980, and in 1982 the Helin and the Shoemaker observing programs
with the 0.46-m Schmidt went their separate ways. Carolyn proved to be very
adept at scanning the Schmidt films, and this new phase of the search program
had its first success with the discovery of (3199) Nefertiti, an Amor
asteroid with its perihelion 0.13 astronomical unit outside the earth's orbit.
In 1983 the first of the record 32 comets associated with the Shoemaker name
was discovered. By the time the observing program ended, in late 1994, it
had produced 40 of the--now--417 known Amor, Apollo and Aten asteroids (the
orbits of this last group being smaller than that of the earth). Together
with the other observing programs at Palomar, the Shoemakers have ensured that
Palomar recently became and is likely to remain the leading site for the
discovery of asteroids, with currently more than 13 percent of asteroids that
have been numbered having been found there. A few months before the Shoemaker
program was terminated came its "defining moment", with Gene receiving the
thrill of his lifetime when some 20 components of one of those 32 comets were
observed to crash into the planet Jupiter with astoundingly dramatic results.
Carolyn also went along on Gene's annual trips to Australia to examine
impact craters, and the tragic irony that his own death should occur there
as the instantaneous result of another violent impact would not have
been lost on him. Gene lived as he died, active to the hilt, his enquiring
mind participating in the adventure of ever learning more over an unusually
large range of scientific disciplines. His many honors included the
Wetherill Medal of the Franklin Institute in 1965, election to membership
in the National Academy of Sciences in 1980, the Gilbert Award of the
Geological Society of America in 1983 and the Kuiper Prize of the
American Astronomical Society in 1984. Above all, he was truly the
"father" of the science of near-earth objects, to the discovery and study
of which The Spaceguard Foundation is dedicated, and his expertise and
drive will be sorely missed.