Scientific Colloquium
March 19, 2010

"The Phoenix Mission to Mars:  Top Ten Discoveries of NASA’s Innovative Explorer of the Red Planet
and the Implications for Bio-habitability

The 2007 Phoenix Mars Scout lander launched on 4 August 2007 and landed on 25 May 2009 at the northern polar latitude of 68.22°N, and longitude 234.25°E (areocentric). The landing site was a field of sand wedge polygonal terrain. For 152 sols the mission made extensive atmospheric and ground measurements. Analyses included interacting with and excavating the Mars regolith with a robotic arm and delivering samples to payload instruments including microscopes (optical and atomic force), a scanning calorimeter-mass spectrometer (TEGA) and an electrochemical analyzer, (WCL).  TEGA confirmed the presence of water ice in the regolith, not bound as a chemical ligand. The salts discovered by WCL offer evidence for the presence in the past of liquid water on Mars.  The presentation will include information about these, as well as, other amazing discoveries on Mars. Sources of bio-energy, key bio-elements and ions, and environmental toxicity and pH will also be discussed with our current understanding of the red planet.

The mission had a goal of sampling to determine whether this environment may have been habitable for life at some time in its history.  Given our current understanding of life, the potential for habitability in a specific time and space encompasses three factors: (1) the presence of liquid water, (2) the presence of a biologically available energy source, and (3) the presence of the chemical building blocks of life (e.g. C, H, N, O, P, S) in a biologically available form. (Additional ions, vital to all life as it is known on Earth, worth examining include K+, Na+, Ca2+, Mg2+, Cl-, Fe2+/3+, NO3-, NO2-, NH4+, SO42-, PO43-.)  In addition to these factors, temperature and water activity must be high enough to support growth. An environment also must be sufficiently benign as to not destroy life attempting development or habitation. These factors must be simultaneously present.  The only way to explore all these factors in one location is to send a suite of instruments.  The Phoenix mission sent such a suite to Mars.  An evaluation of habitability is a precursor requirement for sending any mission to search for life, thus the major discoveries of the mission will be discussed in evaluation of these requirements for life.

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