MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
Contact: Mary Hardin
FOR IMMEDIATE RELEASEMarch 9, 2000
VIEW INSIDE MARS REVEALS RAPID COOLING AND BURIED CHANNELS
Some of Mars' best kept secrets, long buried beneath
the surface of the red planet, were recently revealed by
instruments on NASA's Mars Global Surveyor spacecraft.
New observations of Mars reveal that the planet's flat
northern lowlands were an early zone of high heat flow that later
may have been the site of rapid water accumulation, according to
a view of the Martian interior generated using data from Mars
Global Surveyor, managed by NASA's Jet Propulsion Laboratory,
Pasadena, Calif. Elevation and gravity measurements, which have
been used to probe beneath the surface of Mars, indicate a period
of rapid cooling early in Martian history, and evidence for
large, buried channels that could have formed from the flow of
enormous volumes of water.
This global view of the Martian interior was generated
from gravity measurements with the radio science experiment and
elevation measurements from the Mars Orbiter Laser Altimeter
(MOLA) instruments. Gravity and topography measurements were
combined to reveal the structure of the crust on Mars, which
preserves the record of melting of the interior and the heat loss
from the planet over time.
"The crustal thickness map shows that, as for Earth,
Mars has two distinct crustal provinces," explained Dr. Maria
Zuber of the Massachusetts Institute of Technology,
Cambridge, Mass., and lead author of a study to be published in
the March 10 issue of Science. Beneath the rough southern
highlands and Tharsis volcanic province the crust, estimated at
80 kilometers (50 miles) thick, thins progressively from the
South pole toward the North. In contrast, the northern lowlands
and Arabia Terra region of the southern highlands have a crust of
uniform thickness, about 35 kilometers (22 miles) deep.
The crustal structure accounts for the elevation of the
Martian northern lowlands, which controlled the northward flow of
water early in Martian history, producing a network of valleys
and outflow channels. The new gravity-field data suggest that
the transport of water continued far into the northern plains.
The gravity shows features interpreted as channels buried beneath
the northern lowlands emanating from Valles Marineris and the
Chryse and Kasei Valles outflow regions.
The features are about 200 kilometers (125 miles) wide
and over 1,600 kilometers (1,000 miles) long, with
characteristics that can be explained by water flow on the
surface or in a submarine environment, later buried by sediments.
The large size of these channels implies that any bodies of water
in the northern lowlands could have accumulated rapidly. The
now-buried channels may represent the means for filling an early
The gravity and topography also provide information on
the cooling of Mars over time, which bears on the early climate
and history of water. "The observations suggest that the
northern lowlands was a location of high heat loss from the
interior early in Martian history, probably due to a period of
vigorous convection and possibly plate recycling inside of Mars,"
said Dr. Sean Solomon, Director of the Department of Terrestrial
Magnetism of the Carnegie Institution in Washington, D.C., and a
co-author of the study.
The high heat-loss zone corresponds to the part of Mars
proposed to have been the site of an ancient ocean. The rapid
transport of heat to the surface in this region would have
released onto the surface and into the atmosphere gases and water
or ice trapped in the interior. The time of rapid interior heat
loss may correspond to the period when Mars had a warmer climate,
liquid water flowed on the surface, and the planet's surface was
shielded from the solar wind by a global magnetic field.
During the ongoing Mars Global Surveyor mapping mission
the radio science and MOLA experiments will continue to collect
data on a near-continuous basis through the end of the mission in
February 2001. The MOLA instrument was designed and built by the
Laser Remote Sensing Branch of the Laboratory for Terrestrial
Physics at NASA's Goddard Space Flight Center, Greenbelt, Md.
The radio science experiment is implemented from the Center for Radio
Astronomy of Stanford University, Palo Alto, Calif. JPL manages
the Mars Global Surveyor mission for NASA's Office of Space
Science, Washington, D.C. JPL is a division of the California
Institute of Technology in Pasadena.
Maps of the interior of Mars may be viewed at http://pao.gsfc.nasa.gov/
Information about the Mars Global Surveyor radio science
investigation can be found at
Information about the MOLA investigation can be found at http://ltpwww.gsfc.nasa.gov/tharsis/mola.html
The Mars Global Surveyor home page is at