FIDO finds Layer Cake!
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At the end of sol 8, scientists were excited to find a rock they named
Pipestone which contained a cross-bedding layer of rock. Cross-bedding
patterns are only formed by wind or water movement and scientists
wanted to drive to Pipestone to get a closer view of the size of material
that made up the layers of that rock. If the grains were small, it would
mean that wind changed the angle of the layer of rock, but if the grains
were as big as pebbles, it would mean water pushed the material in that
direction. Unfortunately, scientists realized that Pipestone was simply too
far for the rover to safely travel on the second day of the FIDO test.
Scientists decided to head to a sturdy piece of bedrock, called Kaibab.
Unlike a boulder or a rock, bedrock is part of the land itself, deeply
connected to the ground. The bedrock is tied to the history of the location
and can tell more about the past climate in that area than a piece of rock
that was moved into that place more recently.
Scientists got to eat their cake and have it too when they discovered
that the bedrock at Kaibab contained cross-bedding similar to what they
had wanted to see in Pipestone.
"The whole issue here is there are several ways to make layers
of land and if you can closely examine the size of materials making up a
cross-bedding layer, you can figure out exactly how it was formed,"
says Larry Crumpler, a research curator at the New Mexico Museum of
Natural History and Science in Albuquerque. "If wind formed the
cross-bedding, it would not have big, coarse grains. Wind picks up and
deposits fine material only. Big pebbles are only left over from river
floods. Oceans and lake beds do not leave cross-bedding layers at all."
So immediately when the scientists saw the size of the small or
"shale"-sized sediments in a cross-bedding pattern, they knew
that this bedrock did not form in an ocean or a lake.
Scientists further refined their knowledge by zooming in with the
Pancam. They discovered that the cross-bedding had big pebbles. This
told the scientists that some sort of river flood came through this area.
The land here was not a lakebed, a seabed or a sand dune in the past.
"So there was a big debate this afternoon because some people
felt we had seen enough here and they wanted to go see something
new 200 meters (656 feet) away. Other scientists thought we hadn't seen enough
through the other great suite of instruments on board the FIDO rover, so
they wanted to stay to make different discoveries," says Larry
The team decided to make the "should I stay or should I
go" decision after the next pre-planned stop in the local vicinity.
With equally compelling arguments, the team members are not only looking
for new discoveries, but something to tip the scales in favor of one move
versus another versus staying put.
Larry explains that the advanced rover technology is both exciting and
frustrating. "For the first time we have a highly sophisticated rover
with amazing tools, and through this test we're learning how to make it
really act like a human geologist. But the frustrating part is that humans
on Earth can work 10 times faster than a rover on Mars, and we get so
anxious to take advantage of our field geologist that it's hard to be
patient. Nonetheless it's an incredible advance over past missions. With a
rover like this, we can test our hypothesis and make more thorough
discoveries. In the past, landers and rovers couldn't move this far this
quickly, so we could only research the area immediately in front of the
lander. Now we can move to multiple areas, compare and contrast, and
tell in more detail what really happened here."