Mars Astrobiology: Recent Status and Progress - Planetary Exploration and Science: Recent Results and Advances - page 145

Fig. 8.1 Planet Mars as photographed by the NASA's robotic Hubble Space Telescope spacecraft
( http://hubblesite.org/newscenter/archive/releases/2001/24/image/a/ - NASA/STScI/AURA, June
26, 2001)
chemolithoautotrophic microorganisms, as well as ancient water, including fluvial-
lacustrine environments (plains related to ancient rivers or lakes) that may have been
habitable (Grotzinger 2014 ; Various 2014 ). The search for evidence of habitability,
taphonomy (related to fossils), and organic carbon on planet Mars is now a primary
NASA objective (Grotzinger and MSL Science Team 2014 )(Fig. 8.2 ).
Chemical, physical, geological, and geographic attributes shape the environments
on Mars. Isolated measurements of these factors may be insufficient to deem an
environment habitable, but the sum of measurements can help predict locations with
greater or lesser habitability potential.
The two current ecological approaches for predicting the potential habitability
of the Martian surface use 19 or 20 environmental factors, with emphasis on water
availability, temperature, presence of nutrients, an energy source, and protection
from solar ultraviolet and galactic cosmic radiation (Schuerger et al. 2012 ).