Carrie Hritz, AM'01,
studies archaeology in a place she has never set foot. Ancient
Mesopotamia lies mainly within the borders of modern Iraq,
off limits to American archaeologists since the 1991 Gulf
War. But that hasn't prevented Hritz, a graduate student
in Near Eastern Languages & Civilizations, from pursuing
her research. Hritz studies Mesopotamia in a basement room
at the Oriental Institute (OI), using photographs taken
by American spy satellites three and four decades ago.
She is looking for clues to what she
calls "relic landscapes." The mounds of ancient
cities and towns create much the same pattern of light and
shadow as do craters on the moon. Faint lines crisscrossing
the desert reveal long-abandoned canals. The photos have
helped her find such canals well beyond the area where they
were known to exist, shedding new light on the extent of
ancient Mesopotamian irrigation and the civilization that
depended on it. "We knew it was complex," Hirtz
said, "but from viewing these things, it was even more
complex than I thought."
The United States launched its first
spy satellite in 1960, just months after the Soviets shot
down a U-2 spy plane. Special cameras mounted on the satellites
photographed Earth in broad strips as the satellites passed
overhead. When a canister of film was exposed, it was ejected
and snagged by an airplane over the Pacific.
Archaeologists in the OI use photos taken
by CORONA satellites between 1963 and 1980—when U.S.
intelligence was keenly interested in what was going on
in China, the Soviet Union, and Eastern Europe, but also
in the Middle East, part of the contested ground of the
Cold War. Arthur C. Lundahl, SB'39, SM'42, an expert in
photointelligence who worked on the U-2 spy plane program
and later on the early spy satellite programs (he briefed
President Kennedy on reconnaissance photos during the Cuban
missile crisis), recognized early on that the imagery had
civilian uses. He suggested that the photos be shared with
civilian government agencies, a practice that began in 1967.
In the early 1990s Smithsonian Institution secretary Robert
McCormick Adams, AB'47, AM'52, PhD'56, urged the government
to declassify the images and make them available to the
public. No one knew better than Adams, who had done archaeological
surveys in Iraq and elsewhere in the Middle East, how valuable
the photos would be to scientists. "There was a general
awareness that this was an extraordinary new thing that
would extend our capabilities beyond anything we had seen,"
said Adams, now an adjunct professor at the University of
California, Davis.
Since becoming available in 1996 these
Cold War spy photos have proved an unexpected boon for archaeologists.
Allowing them to study places they cannot visit in person
is only the beginning. The greatest usefulness lies in the
photos' power to reveal features that are almost invisible
on the ground. A discoloring of the soil, a difference in
vegetation, or even slight changes of terrain show up with
remarkable clarity. And because the photographs cover wide
areas, they are helping archaeologists study broad patterns
of land use in the ancient world.
"This is a tool, but it's a fundamental
tool," said Tony Wilkinson, associate professor in
Near Eastern Languages & Civilizations. A pioneer in
using satellite imagery, in 1999 he started the OI's Center
for Archaeology of the Middle East Landscape, or CAMEL.
Jason Ur, who like Hritz is a CAMEL researcher
and a graduate student in Near Eastern Languages & Civilizations,
studies the rise of cities in upper Mesopotamia—now
Syria—toward the end of the fifth millennium B.C. He
has visited the area twice, but his real insights have come
from satellite imagery. Using Geographic Information System
(GIS) software he loads satellite photos into a computer,
marks the position of all the ancient settlements he can
find, and then traces the roads between the settlements.
The roads—archaeologists call them "hollow ways"—are
shallow depressions about 100 yards wide and two to three
feet deep, formed by the passing of people and herds over
many centuries.
"These things are next to impossible
to find on the ground," said Ur, sitting before an
OI computer screen. But they show up on the photos, and
when he marks them in red on the computer, the result is
startling. Bright starbursts appear on the screen, showing
roads radiating from major settlements. Such images reveal
many details, including the surprising density of ancient
settlements, the agricultural territories exploited by different
towns and villages, and the economic relationships between
places.
Satellite imagery cannot replace fieldwork.
In some terrains, like hills and mountains, the photos are
powerless to show the subtle variations of soil and topography
that reveal archeological sites. And at some point archaeologists
must check what they see in the photos against "ground
truth." To know that a particular pattern of light
and dark is an ancient mound, the archaeologist must visit
such a site in person. But once that relation—a key
to the photos, so to speak—is established, large parts
of the landscape can be interpreted. Carrie Hritz's ground
truth is fieldwork done by Adams in the 1950s and 1960s.
By seeing how sites he visited appear in satellite images,
she can find similar sites in areas he could not reach.
The photos not only are providing new
answers to old questions in archaeology—where did people
live and when?—but also are raising new questions about
how people shaped and ordered the ancient landscape.
"That's the way new questions
develop," Wilkinson said. "You get new technology
and you suddenly think of new questions you didn't think
of before."
— R.M.
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