http://www.buffalo.edu/news/fast-execute.cgi/article-page.html?article=60460009
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, [EMAIL PROTECTED]
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
which 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
different 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."
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