PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
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Contact: Mary A. Hardin, JPL, (818) 354-0344
David Schulz, University of Texas at Dallas (972) 883-2293
FOR IMMEDIATE RELEASEDecember 6, 1996
SPACE RADAR UNEARTHS SECRETS OF THE ANCIENT NILE
One of the many great mysteries of the Nile River may be
solved with the discovery of an ancient river channel buried
under layers of sand in the Sahara Desert in Africa.
The buried river channel was revealed in images taken by the
Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-
C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994.
The radar images were processed at NASA's Jet Propulsion
Laboratory and the University of Texas at Dallas (UTD).
"One of the things this discovery helps us examine is the
origin of what's called the Great Bend of the Nile," said Dr. Bob
Stern, a SIR-C science team member at UTD. "The Nile generally
flows due north, but in the Sudan, it makes a huge, looping bend
that is really remarkable because the river is flowing through
the Sahara Desert, the largest, driest desert on the face of the
Earth. There must be a very good reason for the river to make
this great bend, otherwise we would expect it to flow straight to
the Mediterranean Sea." Instead, it bends southwestward and
wanders through the Sahara for another 320 kilometers (200 miles)
before resuming its northward course.
"The discovery of the river channel shows us that probably
sometime between 10,000 and 1 million years ago, the Nile was
forced to abandon its bed and take up a new course to the south.
This buried channel proves that this region has been tectonically
active and shows us how this activity has forced the river to
change its course," Stern said. "Understanding what controls the
course of the Nile is a critical part of understanding Nile
history and predicting Nile behavior, which is important because
the river is essential to millions of people in Egypt, Sudan and
A scientific paper on the discovery written by Stern and co-
authored with UTD geologist Dr. Mohamed Gamal Abdelsalam appears
in the Dec. 6 issue of Science magazine. The discovery grew out
of research that the scientists have been doing on plate
tectonics and the formation of a "supercontinent" more than 600
million years ago.
"Our original experiment involved studying ancient
structures in Precambrian rocks that formed where two
supercontinents collided hundreds of millions of years ago. In
the course of our study, we became interested in how these
structures influenced the course of the Nile," explained Stern.
It was the tantalizing radar images of the area hidden
beneath the sands of the Sahara that turned the scientists' work
in a new direction.
"This discovery wouldn't have happened without SIR-C/X-SAR
imagery. Our work in northeast Africa would have been limited to
what we could see on the ground or could be seen in satellite
photographs. The radar is much more efficient in getting
information from these sand-covered areas because the radar waves
are able to penetrate the sand. SIR-C/X-SAR imagery has revealed
a huge piece of the Earth's surface -- an area that's never been
seriously explored before," Stern noted.
"This is one of the most exciting discoveries from the SIR-
C/X-SAR mission to date. I expect we'll continue to be surprised
by fascinating results like these as the science team continues
to analyze the radar data," said Dr. Diane Evans, the SIR-C
project scientist at NASA's Jet Propulsion Laboratory. "More and
more we are finding the radar data have applications to answer
questions about the Earth that were not originally anticipated."
SIR-C/X-SAR is a joint mission of the United States, German
and Italian space agencies. The Jet Propulsion Laboratory built
and manages the SIR-C portion of the mission for NASA's Office of
Mission to Planet Earth, a program to study the Earth's land,
oceans, atmosphere and life as a total, integrated system.
NOTE TO EDITORS: A NASA Television Video File will feature an
interview with Dr. Bob Stern and the space radar images on
Friday, December 6 at 9 a.m., noon, 3 p.m., 6 p.m. and 9 p.m.
Pacific Time. NASA Television is carried on Spacenet 2,
transponder 5 (channel 9) at 69 degrees west longitude. The
frequency is 3880 MHz. Polarization is horizontal and audio is
monaural at 6.8 MHz.
The images are also available on the World Wide Web at