NASA Data Shed New Light About Water and Volcanoes on Mars

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Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
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William Jeffs 281-483-5111
Johnson Space Center, Houston
william.p.jeffs@nasa.gov

NEWS RELEASE: 2010-294 Sept. 9, 2010

NASA DATA SHED NEW LIGHT ABOUT WATER AND VOLCANOES ON MARS

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2010-294&cid=release_2010-294

PASADENA, Calif. -- Data from NASA's Phoenix Mars Lander suggest liquid water has
interacted with the Martian surface throughout the planet's history and into modern times. The
research also provides new evidence that volcanic activity has persisted on the Red Planet into
geologically recent times, several million years ago.

Although the lander, which arrived on Mars on May 25, 2008, is no longer operating, NASA
scientists continue to analyze data gathered from that mission. These recent findings are based on
data about the planet's carbon dioxide, which makes up about 95 percent of the Martian
atmosphere.

"Atmospheric carbon dioxide is like a chemical spy," said Paul Niles, a space scientist at NASA's
Johnson Space Center in Houston. "It infiltrates every part of the surface of Mars and can
indicate the presence of water and its history."

Phoenix precisely measured isotopes of carbon and oxygen in the carbon dioxide of the Martian
atmosphere. Isotopes are variants of the same element with different atomic weights. Niles is
lead author of a paper about the findings published in Thursday's online edition of the journal
Science. The paper explains the ratios of stable isotopes and their implications for the history of
Martian water and volcanoes.

"Isotopes can be used as a chemical signature that can tell us where something came from, and
what kinds of events it has experienced," Niles said.

This chemical signature suggests that liquid water primarily existed at temperatures near freezing
and that hydrothermal systems similar to Yellowstone's hot springs have been rare throughout
the planet's past. Measurements concerning carbon dioxide showed Mars is a much more active
planet than previously thought. The results imply Mars has replenished its atmospheric carbon
dioxide relatively recently, and the carbon dioxide has reacted with liquid water present on the
surface.

Measurements were performed by an instrument on Phoenix called the Evolved Gas Analyzer.
The instrument was capable of doing more accurate analysis of carbon dioxide than similar
instruments on NASA's Viking landers in the 1970s. The Viking Program provided the only
previous Mars isotope data sent back to Earth.

The low gravity and lack of a magnetic field on Mars mean that as carbon dioxide accumulates in
the atmosphere, it will be lost to space. This process favors loss of a lighter isotope named
carbon-12 compared to carbon-13. If Martian carbon dioxide had experienced only this process
of atmospheric loss without some additional process replenishing carbon-12, the ratio of carbon-
13 to carbon-12 would be much higher than what Phoenix measured. This suggests the Martian
atmosphere recently has been replenished with carbon dioxide emitted from volcanoes, and
volcanism has been an active process in Mars' recent past. However, a volcanic signature is not
present in the proportions of two other isotopes, oxygen-18 and oxygen-16, found in Martian
carbon dioxide. The finding suggests the carbon dioxide has reacted with liquid water, which
enriched the oxygen in carbon dioxide with the heavier oxygen-18.

Niles and his team theorize this oxygen isotopic signature indicates liquid water has been present
on the Martian surface recently enough and abundantly enough to affect the composition of the
current atmosphere. The findings do not reveal specific locations or dates of liquid water and
volcanic vents, but recent occurrences of those conditions provide the best explanations for the
isotope proportions.

The Phoenix mission was led by principal investigator Peter H. Smith of the University of
Arizona in Tucson, with project management at NASA's Jet Propulsion Laboratory in Pasadena,
Calif. JPL is a division of the California Institute of Techology in Pasadena. The University of
Arizona provided the lander's Thermal and Evolved Gas Analyzer.

For more information about the Phoenix mission, visit http://www.nasa.gov/phoenix .

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