[meteorite-list] NASA Data Shed New Light About Water and Volcanoes on Mars (Phoenix)

[Ron Baalke]

Sep. 9, 2010

Dwayne Brown 
Headquarters, Washington      
202-358-1726 
dwayne.c.brown at nasa.gov 

William Jeffs 
Johnson Space Center, Houston 
281-483-5111 
william.p.jeffs at nasa.gov 
RELEASE: 10-216

NASA DATA SHED NEW LIGHT ABOUT WATER AND VOLCANOES ON MARS

HOUSTON -- 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. 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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