SPACE RADAR UNEARTHS SECRETS OF THE ANCIENT NILE

Fri, 6 Dec 1996 14:00:20 -0500 (EST)
Source: NASANews@hq.nasa.gov

  Douglas Isbell
Headquarters, Washington, DC                 December 6, 1996
(Phone: 202/358-1753)
Sender: owner-press-release
Precedence: bulk

Mary Hardin
Jet Propulsion Laboratory, Pasadena, CA
(Phone: 818/354-5011)

Dave Schulz
University of Texas at Dallas
(Phone: 972/883-2293)

RELEASE:  96-251

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 (JPL), Pasadena, CA, 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 southwestwards and wanders
through the Sahara for another 200 miles before resuming its northward course.

    "The discovery of the river channel shows us that probably sometime
between 10,000 and 1,000,000 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 Ethiopia."

    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 JPL. "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. JPL 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.

                               -end-

    A still color image to illustrate this release is available to news
media by contacting the Headquarters Imaging Branch at 202/358-1900.  The
photo number is 96-HC-754.


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