Scientists examining what NASA's Opportunity is showing them about Mars rocks
are seeing into the past, and what they're seeing indicates water once flowed there.
This image, taken by Opportunity's microscopic
imager, shows a geological region of the rock outcrop at Meridiani Planum,
Mars dubbed "El Capitan." Light from the top is illuminating the region.
Several images, each showing a different part of this region in good focus,
were merged to produce this view. The area in this image is 1.5 centimeters
(0.6 inches) across. Image Credit: NASA/JPL/US Geological Survey
The outcrop right next to where Opportunity landed holds evidence that the
spent time drenched in liquid water.
Members of the Mars Exploration Rovers' international science team presented
evidence to news reporters at NASA Headquarters in Washington on March 2.
"Liquid water once flowed through these rocks. It changed their texture,
and it changed
their chemistry," said Dr. Steve Squyres of Cornell University, Ithaca,
investigator for the science instruments on Opportunity and its twin, Spirit. "We've
able to read the tell-tale clues the water left behind, giving us confidence
This mosaic of images taken by Opportunity's panoramic
camera shows the rock region dubbed "El Capitan," which lies within the larger
outcrop near the rover's landing site. Image Credit: NASA/JPL/Cornell
Dr. James Garvin, lead scientist for Mars and lunar exploration at NASA Headquarters,
Washington, said, "NASA launched the Mars Exploration Rover mission specifically
check whether at least one part of Mars ever had a persistently wet environment
could possibly have been hospitable to life. Today we have strong evidence
exciting answer: Yes."
This high-resolution image captured by Opportunity's
panoramic camera highlights the puzzling rock outcrop near the rover's
landing site. These layered rocks measure only 10 centimeters (4 inches)
tall, about the height of a street curb.
Image Credit: NASA/JPL/Cornell
Clues from the rocks' appearance and composition support the conclusion that
were altered by exposure to liquid water after they were formed. However, the
don't tell how long the wet conditions lasted, and the clues are only tantalizing,
conclusive, about whether the environment was watery when the rocks originally
This image, taken by the microscopic imager on Opportunity, illustrates the
shapes of the vugs, or small cavities, located on the region dubbed "El Capitan." The
region is part of the rock outcrop at Meridiani Planum, Mars, which the rover
is currently examining. Image Credit: NASA/JPL/US Geological Survey
Opportunity arrived just five weeks ago at a carefully selected landing area
Meridiani Planum region. On landing day, it happened to roll to a stop inside
crater that has an outcrop of bedrock. Most days since then, the rover has
or inspecting the outcrop.
+ View Photo: Two Outcrop Sites Where Opportunity Found Water Evidence
Scientists and engineers assembled at NASA's Jet
Laboratory in Pasadena, Calif., plan to keep Opportunity busy at the outcrop
more days, perhaps gaining more evidence about whether the rocks were originally
down in a wet setting, such as the bottom of a shallow lake or a hydrothermal
Later, the rover will venture out to the surrounding plain and may hunt for
putting the discoveries within the crater into a broader regional context.
Here are some of the clues that water formerly pervaded the rocks where Opportunity
-- The rover's alpha particle X-ray spectrometer found lots of sulfur in the
Related clues from that instrument and the miniature thermal emission spectrometer
suggest the sulfur is in the form of sulfate salts, an indicator that the rocks
soaked with water.
-- The rover's Moessbauer spectrometer detected jarosite, a hydrated iron
that could result from the target rock spending time in an acidic lake or acidic
-- Pictures from Opportunity's panoramic camera and microscopic imager show
small, tablet-shaped or disc-shaped holes in an outcrop rock selected for close-up
examination. These holes, or "vugs," match the distinctive appearance
of Earth-rock vugs
that form where crystals of salt minerals grow inside rocks that sit in briny
disappear by eroding or dissolving.
-- The cameras have revealed spheres the size of BBs embedded in outcrop rocks.
spherules are not concentrated at particular layers within the rock, as they
would likely be
if they originated outside the rock and were deposited onto accumulating layers
rock was forming. That makes the spherules likely to be concretions that formed
accumulation of minerals coming out of solution inside a porous, water-soaked
-- Some of the spherules in pictures from the microscope appear to have stripes
correspond to layering of the matrix rock around them. This would be consistent
interpretation that the spherules are concretions that formed inside a wet
Opportunity is adding further observations in coming days to pursue other
evidence about the rocks' water history, such as telltale patterns within the
in the outcrop.
NASA's Jet Propulsion Laboratory