archive: SETI FIRST GLOBAL 3-D VIEW OF MARS REVEALS DEEP BASIN AND PATHWAYS

SETI FIRST GLOBAL 3-D VIEW OF MARS REVEALS DEEP BASIN AND PATHWAYS

Larry Klaes ( lklaes@bbn.com )
Thu, 27 May 1999 14:54:39 -0400

>Date: Thu, 27 May 1999 14:10:12 -0400 (EDT)
>From: NASANews@hq.nasa.gov
>Subject: FIRST GLOBAL 3-D VIEW OF MARS REVEALS DEEP BASIN AND PATHWAYS FOR
WATER FLOW
>Sender: owner-press-release@lists.hq.nasa.gov
>To: undisclosed-recipients:;
>
>Douglas Isbell
>Headquarters, Washington, DC May 27, 1999
>(Phone: 202/358-1753)
>
>Cynthia M. O'Carroll
>Goddard Space Flight Center, Greenbelt, MD
>(Phone: 301/614-5563)
>
>Mary Hardin
>Jet Propulsion Laboratory, Pasadena, CA
>(Phone: 818/354-0344)
>
>RELEASE: 99-66
>
>FIRST GLOBAL 3-D VIEW OF MARS REVEALS
>DEEP BASIN AND PATHWAYS FOR WATER FLOW
>
> An impact basin deep enough to swallow Mount Everest and
>surprising slopes in Valles Marineris highlight a global map
>of Mars that will influence scientific understanding of the
>red planet for years.
>
> Generated by the Mars Orbiter Laser Altimeter (MOLA), an
>instrument aboard NASA's Mars Global Surveyor, the high-
>resolution map represents 27 million elevation measurements
>gathered in 1998 and 1999. The data were assembled into a
>global grid with each point spaced 37 miles (60 kilometers)
>apart at the equator, and less elsewhere. Each elevation
>point is known with an accuracy of 42 feet (13 meters) in
>general, with large areas of the flat northern hemisphere
>known to better than six feet (two meters).
>
> "This incredible database means that we now know the
>topography of Mars better than many continental regions on
>Earth," said Dr. Carl Pilcher, Science Director for Solar
>System Exploration at NASA Headquarters, Washington, DC.
>"The data will serve as a basic reference book for Mars
>scientists for many years, and should inspire a variety of
>new insights about the planet's geologic history and the ways
>that water has flowed across its surface during the past four
>billion years."
>
> "The full range of topography on Mars is about 19 miles
>(30 kilometers), one and a half times the range of elevations
>found on Earth," noted Dr. David Smith of NASA's Goddard
>Space Flight Center, Greenbelt, MD, the principal
>investigator for MOLA and lead author of a study to be
>published in the May 28, 1999, issue of Science.
>
> "The most curious aspect of the topographic map is the
>striking difference between the planet's low, smooth Northern
>Hemisphere and the heavily cratered Southern Hemisphere,"
>which sits, on average, about three miles (five kilometers)
>higher than the north, Smith added. The MOLA data show that
>the Northern Hemisphere depression is distinctly not
>circular, and suggest that it was shaped by internal geologic
>processes during the earliest stages of martian evolution.
>
> The massive Hellas impact basin in the Southern
>Hemisphere is another striking feature of the map. Nearly
>six miles (nine kilometers) deep and 1,300 miles (2,100
>kilometers) across, the basin is surrounded by a ring of
>material that rises 1.25 miles (about two kilometers) above
>the surroundings and stretches out to 2,500 miles (4,000
>kilometers) from the basin center.
>
> This ring of material, likely thrown out of the basin
>during the impact of an asteroid, has a volume equivalent to
>a two-mile (3.5-kilometer) thick layer spread over the
>continental United States, and it contributes significantly
>to the high topography in the Southern Hemisphere.
>
> The difference in elevation between the hemispheres
>results in a slope from the South Pole to North Pole that was
>the major influence on the global-scale flow of water early
>in martian history. Scientific models of watersheds using
>the new elevation map show that the Northern Hemisphere
>lowlands would have drained three-quarters of the martian
>surface.
>
> On a more regional scale, the new data show that the
>eastern part of the vast Valles Marineris canyon slopes away
>from nearby outflow channels, with part of it lying a half-
>mile (about one kilometer) below the level of the outflow
>channels.
>
> "While water flowed south to north in general, the data
>clearly reveal the localized areas where water may have once
>formed ponds, " explained Dr. Maria Zuber of the
>Massachusetts Institute of Technology, Cambridge, MA, and
>Goddard.
>
> The amount of water on Mars can be estimated using the
>new data about the south polar cap and information about the
>North Pole released last year. While the poles appear very
>different from each other visually, they show a striking
>similarity in elevation profiles. Based on recent
>understanding of the North Pole, this suggests that the South
>Pole has a significant water ice component, in addition to
>carbon dioxide ice.
>
> The upper limit on the present amount of water on the
>martian surface is 800,000 to 1.2 million cubic miles (3.2 to
>4.7 million cubic kilometers), or about 1.5 times the amount
>of ice covering Greenland. If both caps are composed
>completely of water, the combined volumes are equivalent to a
>global layer 66 to 100 feet (22 to 33 meters) deep, about
>one-third the minimum volume of a proposed ancient ocean on
>Mars.
>
> During the ongoing Mars Global Surveyor mission, the
>MOLA instrument is collecting about 900,000 measurements of
>elevation every day. These data will further improve the
>global model, help engineers assess the area where NASA's
>Mars Polar Lander mission will set down on Dec. 3, and aid
>the selection of future landing sites. MOLA was designed and
>built by the Laser Remote Sensing Branch of the Laboratory
>for Terrestrial Physics at Goddard. The Mars Global Surveyor
>mission is managed for NASA's Office of Space Science,
>Washington, DC, by the Jet Propulsion Laboratory, Pasadena,
>CA, a division of the California Institute of Technology.
>
> MOLA topographic images may be viewed at the following
>web address:
>
>http://pao.gsfc.nasa.gov/gsfc/spacesci/pictures/mola/mars3d.h
>tm
>
> More details about the MOLA instrument and science
>investigation can be found at:
>
> http://ltpwww.gsfc.nasa.gov/tharsis/mola.html
>
> -end-
>
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