Measurements by NASA's Phoenix Mars Lander suggest liquid water has interacted with the Martian surface throughout the planet's history, but the findings also suggest that liquid water has primarily existed at temperatures near freezing. Additionally, analysis of the composition of the Martian atmosphere revealed that volcanism has been an active process in the planet's geologically recent past.
The findings, published in the Sept. 10 issue of the journal Science, also suggest that liquid water has primarily existed at temperatures near freezing, implying hydrothermal systems similar to Yellowstone's hot springs on Earth have been rare on Mars throughout its history.
These surprising results come from measurements Phoenix made in 2008 of stable isotopes of carbon and oxygen in the carbon dioxide of the Martian atmosphere. Isotopes are variants of the same element with a different number of neutrons, such as carbon-12, with six neutrons, and the rarer carbon-13, with seven.
Unprecedented precision in determining the ratios of isotopes in Martian carbon dioxide sheds new light on the history of water and volcanic activity on the surface of Mars.
The measurements were performed by the Evolved Gas Analyzer on Phoenix, part of the lander's Thermal and Evolved Gas Analyzer, or TEGA, an instrument designed and built at the University of Arizona. TEGA's mass spectrometer was capable of a more accurate analysis of carbon dioxide than the ones on NASA's Viking landers in the 1970s, the only other such instruments that have returned results on isotopic composition from Mars.