March 2, 2004 | David F. Coppedge

Opportunity Finds Evidence of Past Water on Mars

Liquid water once drenched the surface of Mars at Meridiani Planum and made it a suitable habitat for life, according to Ed Weiler at a NASA briefing today.  Four pieces of evidence from the Mars Exploration Rover named Opportunity led principal scientist Stephen Squyres to this conclusion: (1) the spherules appear to be concretions grown within a water-saturated rock; (2) the rock is permeated with tabular holes that seem to be gaps left by dissolved-away crystals; (3) the X-ray spectrometer and mini-TES saw a strong signature of sulfur in ground-away rock, indicating the presence of sulfate salts; (4) the Mossbauer spectrometer found an abundance (10%) of iron sulfate hydrate named jerusite that only forms in the presence of water.
    Combined, these evidences make it “hard to avoid the conclusion” that water existed for some period of time in this environment (how long, Squyres admitted, is impossible to say from these data). Whether the rock outcrops were laid down in water remains to be determined.  Scientists will be investigating preliminary hints at crossbedding in the bedrock, which would indicate a sedimentary process.  High concentration of magnesium sulfate, like dehydrated Epson salt, were found, indicating that the salts likely precipitated out of solution.  The salts appear similar to what would remain if a salty body like the Dead Sea evaporated.
    Squyres said this could have been a habitable environment for life, but cautioned this doesn’t mean life existed on Mars.  It might be a good place to look, though: the crystal evidence suggests evidence for past life might have been trapped in the rocks.  It might take a sample return mission to tell.  Fossils would be very rare and unlikely to be found, but the isotopic fractionation signature of sulfur could provide a chemical tracer for life.  Squyres admitted there is no way to date the material.

Don’t just look for water.  Look for information (see 12/30/2002 headline).
    Note: organisms in salty environments on Earth can survive because of specialized adaptations to deal with the salts, which normally would be harmful.  One would not expect life, especially lipid membranes, to evolve in a salty environment (see 09/17/2002 headline).
    Finding evidence of past water is a geologically fascinating discovery, interesting in its own right.  It is disgusting, however, to watch the press assume that water equals life.  They did it at Europa, and you can just hear it coming on all the popular news outlets and TV shows.  Water is the simplest and easiest molecule to get.  In its solid and vapor forms, it is abundant in the solar system (whole moons of Saturn are made of ice).  What sets life apart from rock, dirt, sand and water is the way the material is organized into instruction-directed molecular machines, filled with information.  Given the periodic table and the laws of physics, one can derive the existence of water.  Information – codes – machinery – these are the hallmarks of intelligent design.

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