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Topic Name: NASA Mars Reconnaissance Orbiter Provides Insights About Mars Water and Climate
Category: STAR (Space, Telecommunications & Radioscience)
Research persons: Richard Zurek, Dr. Alfred S. McEwen
Location: 4800 Oak Grove Drive , Pasadena, CA 91109, United States
Details
NASA's Mars Reconnaissance Orbiter (MRO) is examining several features on
Mars that address the role of water at different times in Martian history.
Features examined with the orbiter's advanced instruments include material
deposited in two gullies within the past eight years, polar ice layers formed in
the recent geologic past, and signs of water released by large impacts when Mars
was older.
Last year, discovery of the fresh gully deposits from before-and-after images
taken since 1999 by another orbiter, Mars Global Surveyor, raised hopes that
modern flows of liquid water had been detected on Mars. Observations by the
newer orbiter, which reached Mars last year, suggest these deposits might
instead have resulted from landslides of loose, dry materials. Researchers
report this and other findings from the MRO in five papers in Friday's issue of
the journal Science.
"The key question raised by these two deposits is whether water is coming to the
surface of Mars today." said Alfred McEwen of the
University of Arizona, Tucson,
lead scientist for the spacecraft's High Resolution Imaging Science Experiment
camera and co-author of three of the papers. "Our evidence suggests the new
deposits did not necessarily involve water."
One of the fresh deposits is a stripe of relatively bright material several
hundred yards long that was not present in 1999 but appeared by 2004. The
orbiter's Compact Reconnaissance Imaging Spectrometer for Mars reveals the
deposit is not frost, ice or a mineral left behind by evaporation of salty
water. Also, the researchers inspected the slopes above this and five other
locations that have bright and apparently young deposits. The slopes are steep
enough for sand or loose, dry dust to flow down the gullies. Bright material
seen uphill could be the source.
Other gullies, however, offer strong evidence of
liquid water flowing on Mars
within the last few million years, although perhaps at a different phase of
repeating climate cycles. Mars, like Earth, has periodic changes in climate due
to the cycles related to the planets' tilts and orbits. Some eras during the
cycles are warmer than others. These gullies are on slopes too shallow for dry
flows, and images from MRO's high-resolution camera show clear indicators of
liquid flows, such as braided channels and terraces within the gullies.
Another new finding from that camera may help undermine arguments that very
ancient Mars had a wet climate on a sustained basis. Landscapes with branched
channels and fan-like deposits typical of liquid flows were found around several
impact craters. Images show close association between some of those flow
features and ponded deposits interpreted as material melted by the impact of a
meteoroid into ice-rich crust. This new evidence supports a
hypothesis that
ancient water flows on the surface were episodic, linked to impact events and
subsurface heating, and not necessarily the result of precipitation in a
sustained warmer climate. Crater-digging impacts were larger and more numerous
during the early Martian era when large drainage networks and other signs of
surface water were carved on many parts of the planet.
The MRO has examined ice-rich layered deposits near the Martian poles with the
ground-penetrating Shallow Subsurface Radar instrument, and other experiments.
The radar detected layering patterns near the south pole that suggest climatic
periods of accumulating deposits have alternated with periods of erosion, report
Roberto Seu of the University of Rome and co-authors. Maria Zuber of the
Massachusetts Institute of Technology, and collaborators used effects of Mars'
gravity on the orbiter to check whether layered deposits at the south pole are
high-density material, such as rock, or lower-density such as ice. Their
observations add to other evidence that the layers are mostly water. Kenneth
Herkenhoff of the U.S. Geological Survey, Flagstaff, and others used the
high-resolution camera to trace a series of distinctive layers near the north
pole.
An accompanying paper by Windy Jaeger of the U.S. Geological Survey, Flagstaff,
and co-authors uses images from the high-resolution camera to show lava flows
completely draping a young Martian channel network called Athabasca Valles This
creates ponded lava over an expanse that other researchers had interpreted in
2005 as a frozen sea.
Richard Zurek, project scientist for MRO at NASA's Jet Propulsion Laboratory
(JPL), Pasadena, Calif., said, "These latest increases in observational
capabilities, individually and in combination, reveal a more complex Mars, a
planet with a rich history that we are still learning to read."
JPL manages the MRO mission for NASAs Science Mission Directorate, Washington.
Lockheed Martin Space Systems, Denver, is the prime contractor and built the
spacecraft. The University of Arizona operates the High Resolution Imaging
Science Experiment camera, built by Ball Aerospace & Technology Corp., Boulder,
Colo. The Johns Hopkins University Applied Physics Laboratory, Laurel, Md.,
operates the Compact Reconnaissance Imaging Spectrometer for Mars. The Shallow
Subsurface Radar was provided by the Italian Space Agency; its operations are
led by the University of Rome, and its data analyzed by a joint Italian-U.S.
science team.
About Researcher: Richard Zurek
Jet Propulsion Laboratory
M/S 264-535
4800 Oak Grove Drive
Pasadena, CA 91109
Phone: 818.354.3725
Fax: 818.393.6870
Email:
Richard.W.Zurek@jpl.nasa.gov
MRO Project Scientist
Currently, Dr. Richard Zurek serves as the Project Scientist for the Mars
Reconnaissance Orbiter, launched in August 2005 and now beginning its two-year
primary science phase. As a researcher, Dr. Zurek has studied the upper
atmosphere of the Earth and the atmosphere of Mars, using observational data
acquired by spacecraft such as the Upper Atmosphere Research Satellite (UARS),
Mariner 9, the Viking Orbiters and Landers and the current Mars Global Surveyor
and Mars Odyssey mission.
Education
Dr. Zurek graduated from Michigan State University with a B. Sc. degree in
Mathematics in 1969, and he later received his Ph.D. in Atmospheric Sciences
from the University of Washington (Seattle) in 1974. Following one-year
post-doctoral appointments in research at the National Center for Atmospheric
Research (NCAR) and at the Laboratory for Atmospheric and Space Physics (LASP),
University of Colorado in Boulder, Colorado, he went to work at JPL where he has
been employed since 1976.
Dr. Alfred S. McEwen
Professor
Planetary Geology
Ph.D., 1988, Arizona State University
Contact:
Lunar and Planetary Lab
University of Arizona
Tucson, AZ 85721
Office: Space Sciences 429
Phone: (520) 621-4573
Email: mcewen
Dr. McEwen is a planetary geologist and director of the Planetary Image
Research Laboratory (PIRL) . He is a
member of the imaging science team of the Cassini mission to Saturn;
co-investigator on the Lunar Reconnaissance Orbit Camera (LROC) team;
participating scientist on Mars Odyssey THEMIS; and PI of the High Resolution
Imaging Science Experiment (HiRISE)
for Mars Reconnaissance Orbiter (
MRO ) . For Cassini
he is leading the planning and analysis for imaging observations of Titan's
surface. For Mars he is focusing on studies of recent flood lavas and fluvial
features, terrestrial analogs, evaluation of potential future landing sites, and
studies of small craters. HiRISE is Alfred's major project for the next decade.
MRO launched in August 2005, and will arrive at Mars in March 2006, and begin
the science phase in December 2006, continuing until 2009 or later.
Related Online Resources:
http://www.nasa.gov/mission_pages/MRO/spacecraft/sc-instru-crism.html
http://www.agu.org/pubs/crossref/2007/2006JE002682.shtml
http://www.planetary.org/blog/article/00000789/
http://en.wikipedia.org/wiki/Hypothesis
http://www.usgs.gov/
 
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