• Life on Mars

  Geology professor spends summer looking for life on Mars.

• The story begins 4.5 billion years ago when rock was formed on Mars.
  
  Fast-forward to 15 million years ago to a point in time when a huge comet or asteroid impacted the Martian surface and cast meteorites into the solar system.
  
  The meteorites traveled through space for millions of years until they were captured by another planet’s gravitational pull. That happened 13,000 years ago, when a meteorite found its way into the Earth’s orbit before landing on what is now Antarctica.
  
  In 1984 that meteorite (know as ALH84001) was found in the Allan Hills ice field in Antarctica during an expedition by a team from NASA’s Johnson Space Center (JSC).
  It is one of only 14 meteorites from Mars that have been found on Earth. NASA scientists at JSC studying ALH84001 found four independent lines of evidence of ancient life on Mars, including the abundant polycyclic aromatic hydrocarbons (PAHs) detected from the fresh fracture surfaces of the Martian meteorite ALH84001.
  
  In a paper published in 1996, the lead author, David McKay, argues that the PAHs and their associated secondary mineral phases and textures could be fossil remains of a past Martian life form.
  
  Work is still being conducted on ALH84001 by NASA and Jiasong Fang, assistant professor of geological and atmospheric sciences. Fang spent last summer working with McKay and others at NASA as part of the NASA Faculty Fellowship Program (NFFP).
  
  The NFFP offers science and engineering faculty at U.S. colleges and universities hands-on exposure to NASA's research challenges during 10-week summer research residencies and extended research opportunities at participating NASA research centers.
  
  "Searching for evidence of life elsewhere in the universe and specifically within our solar system is one of the most prominent scientific inquires in human history," Fang says, "and determining if life exists elsewhere in the universe is one of the key missions of the Space Science Enterprise areas of NASA."
  
  Fang says an important issue to consider in the search for extinct or extant life on Mars or other planets is the choice of biomarkers. Biomakers must play a major role in the biochemistry of any known organism on Earth if life on Mars and other planets is also carbon-based aqueous chemistry and the biochemistry is the same.
  
  "A basic characteristic of life is the cell membrane, which separates the molecularly highly organized organisms from its far less ordered environment," Fang said. "Phospholipds are major components of cell membranes of all organisms and form lipid bilayers in biomembranes. So we can use phospholipids as biomarkers of choice."
  
  During his summer residency at NASA, Fang worked on several different areas in regards to ALH84001.
  
  "First we wanted to develop an analytical technique that is sensitive and contamination-free, to extract lipids from the meteorite," he said. "Because there is no direct evidence that a living entity evolved or exists on Mars and membrane is a basic characteristic of all life as we know it, analysis for lipids from Martian meteorites would provide an unambiguous way of detecting extinct or extant life on Mars. "
  
  Fang and his NASA counterparts analyzed two lunar (JSC-1) and Mars (JSC MARS-1) regolith simulants for phospholipids ester-linked fatty acids (PLFA) through gas chromatography/mass spectrometry. The Mars and lunar simulants were specifically developed by JSC to support scientific research, engineering studies and education.
  
  "Our findings suggest that bacteria were dominant microorganisms in the simulants," Fang said.
  
  Fang hopes to continue his research at NASA and with McKay again this coming summer when work is scheduled to develop probes that could be used to detect DNA, protein and lipids. Those probes could then be sent to Mars on robotic missions.

Around LAS
December 2-31, 2002