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Mars May Be Much Older -- or Younger -- than Thought, 
According to Research by UB Planetary Geologist

Analysis of Martian volcanoes will help determine
when Hesperian epoch began

Release date: Thursday, January 23, 2003
Contact: Ellen Goldbaum, goldbaum{at}buffalo.edu
         University at Buffalo
Phone: 716-645-5000 ext 1415
Fax: 716-645-3765

BUFFALO, N.Y. -- Research by a University at Buffalo planetary
geologist suggests that generally accepted estimates about the
geologic age of surfaces on Mars -- which influence theories about its 
history and whether or not it once sustained life -- could be way off.

Funded by the National Aeronautics and Space Administration, the
research eventually could overturn principles about the relative ages
of different areas on the Red Planet that have not been questioned for 
nearly 20 years. 

The findings also could cause scientists to reconsider the use of a
critical tool -- counting impact craters created by meterorites --
that geologists use to estimate the age of planets they cannot visit
in person. 

"This has the potential to change everything we thought we knew about 
the age of different surfaces on Mars," said Tracy Gregg, Ph.D., 
assistant professor of geology at UB and chair of the Planetary 
Geology Division of the Geological Society of America.  David Crown, 
Ph.D., of the Planetary Science Institute, is Gregg's co-investigator 
on the grant. 

Gregg's research concerns an area on Mars called Hesperia Planum, 
which has been used since the 1980s to define the Hesperian epoch, the 
second of the planet's three geologic time periods.

But in the past several years, recent analyses of images obtained from 
the Mars Orbiter Laser Altimeter, (MOLA), the Mars Orbiter Camera 
(MOC) and other instruments have led to new estimates for the duration 
of the Hesperian epoch, ranging from just 300,000 years to 1-2 billion 
years, Gregg explained. 

While other planetary geologists now are attempting to reconcile these 
two models, she said, her focus is on trying to figure out hich 
surfaces on Mars originated in the Hesperian epoch, research that, in 
turn, probably will help to further define the duration of the
Hesperian epoch. 

"For almost 20 years, Hesperia Planum has served as the basic time 
marker on Mars," said Gregg. 

"When we want to identify how old rocks are without the benefit of
samples, we count impact craters, the big holes in planetary surfaces 
that are made by meteorites that crash into them," explained Gregg. 
"The more impact craters there are on a surface, the older it is."

But during the course of Gregg's research reviewing images of Tyrrhena 
Patera, a volcano located in the middle of Hesperia Planum, she began 
finding deposits from not one Martian geologic epoch but from several.

Gregg made her findings using images obtained from the Viking Orbiter, 
the Mars Global Surveyor, the MOLA and the MOC. She also will be using 
data NASA is making available from THEMIS, the Thermal Mapping 
Infrared Spectrometer, which measures surface temperatures on Mars.

"Hesperia Planum is not one age. Its surface actually is a combination 
of materials that are very old, materials that are very young and some 
that are in between," she said, "and the volcanoes there are the 
reason why." 

Gregg recently has demonstrated that two volcanoes in western Hesperia 
Planum were active during a much longer period than previously was 
understood and that the products of the eruptions traveled much 
further, signaling a greater intensity of volcanic activity than 
originally was thought. 

Her findings, she said, are similar to ones made about 20 years ago on 
Earth, when geologists discovered that Yellowstone National Park in 
Wyoming was the center crater of an enormous volcano and that its 
deposits stretched as far as the state of Illinois. 

Those findings, she said, changed fundamentally the understanding of 
volcanic activity on Earth. 

In a similar vein, she said, the new observations about the great
distances traveled by deposits of Martian volcanoes and their
influence on the age of surfaces may cause a similar reconsideration
of understanding of the history of Mars. 

"I think that we are about to discover that Hesperia Planum, this
surface that has acted as a basic time marker for Mars, has a very
ifferent age than we thought," she said. "If it turns out it's much
older than we thought, then it means that the system shut down a lot 
earlier and the chances of finding active living organisms on Mars are 
much slimmer. 

"If, on the other hand, it turns out to be much younger, then it means
Mars still may be volcanologically active, and if it is, that 
increases the possibility of extant life on Mars."


http://www.buffalo.edu/news/fast-execute.cgi/article-page.html?article=60460009

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