strobiology is the study of life in the universe.  JSC scientists from many disciplines are investigating the origin and evolution of life.
 
The building blocks of life — hydrogen, carbon, nitrogen, oxygen, sulfur, and phosphorus — are the biogenic elements from which all living things are made.  These essential elements, created during the Big Bang and subsequent star formation, exist throughout the universe.  Physical forces such as comet and meteor impacts, planetary atmospheres, and ecosystem interactions all affect the evolution of biogenic elements.

Ancient Life on Earth
The formation of Earth and its atmosphere made it possible for life to begin and evolve over time.  Life on this planet has been traced back 3.8 billion years to the period when heavy cometary bombardment brought life-giving water and organic chemicals to Earth.  The evolutionary record of Earth is crucial to the search for extraterrestrial life.  Our past holds the only clues to how, why, or when living creatures might arise elsewhere in the universe.

Life Endures Earth's Extreme Environments
Astrobiology research has revealed life's habitable zone to be much broader than we originally thought.  Life has been found thriving in Antarctic rocks, in boiling hot springs, in the ocean depths, and deep underground.

   Antarctica
Antarctica is the least hospitable place on Earth.  Yet, exobiologists have uncovered thriving populations of life in the dry valleys and ice covered lakes.  This finding suggests that extreme cold and minimal water need not preclude life on Mars-like planets.

  Hot Springs
Carbonate thermal springs can support thermophilic (heat loving) microbes at temperatures above 70ºC (158ºF).  A range of micro-organisms are found in the heated waters of Yellowstone and Hot Springs National Parks.  The existence of these organisms suggests the range of life which may have evolved within the Martian surface.

  Subterranean Environments
Bacteria has been found in rocks buried up to two miles underground.  There may be more organisms living underground than at the Earth's surface.

Possible Life Beyond Earth
A rock from the ancient martian crust has revealed tantalizing hints of fossil micro-organisms that may have lived more than three billion years ago.  Liquid water, the essential ingredient for life, once flowed on the surface of Mars.  Water probably exists today, below the icy crust of Jupiter's moon, Europa.  The search for life within the solar system will continue on planned spacecraft missions to Mars, Europa, Comet Wild-2, and Titan.

Mars Meteorites
Scientists have determined that 15 meteorites were originally from Mars.  The composition of gases found in some of these rocks is nearly identical to the composition of the gases in the martian atmosphere measured by Viking.
 
Carbonate globules, found in ALH840001, are surrounded by black and white rims.  Using a scanning electron microscope, scientists probed deeper into the carbonate globules and discovered features that resemble fossilized bacteria.
 
Not knowing whether the martian features are truly biogenic, scientists compared them to known biogenic filaments growing deep beneath the surface, in a region called the Columbia River Basalt.
 
Examination of a thin section of the carbonate globule revealed tiny mineral grains, called magnetites.  Magnetite, composed of iron and oxygen, gives information about possible biogenic activity.  It is well documented that magnetotactic bacteria on Earth produce magnetite grains with sizes and shapes nearly identical to some of the magnetites found within the martian carbonate globules.