"Hematite is a special place. It's one
of three sites on Mars with detectable mineral signatures for coarse grained
hematite." This type of Hematite generally forms in water,
so "finding hematite is like finding a sign that says 'Water
Not only does it rank high in scientific interest; Hematite measures
high on the safety scale as well. Of the four sites, Golombek said,
Hematite is very unique: "it's one of the smoothest, flattest,
safest place in the equatorial region. All the other sites have good
things about them and not-so-good things about them."
The Melas region is a canyon with 10-kilometer
high walls (6 miles high) that "make the Grand Canyon look
insignificant," said Golombek. "There is a area at its very
center that has interior deposits that look like some type of sedimentary
rock. Did these rocks form in water, was there a lake there? Were the
layers deposited by water? Are they due to wind erosion or some other
process? It's a prime place to address very important questions."
Attractive though it is, said Golombek, Melas is surrounded by sand
dunes. A bullseye in targeting would put the lander in fascinating terrain,
but anything short of that could be disappointing.
"Gusev is perhaps the classic crater that looks like it was a
crater lake," said Golombek.. "For all the world, it looks like a
crater that filled with water, which at some point breached the crater wall
and the water escaped. If this occurred, the crater should be filled with
sediments deposited in the lake." And if the sediments are there,
they were laid down in watery solutions that will provide valuable clues in
the search for water's past on Mars.
The original landing ellipse considered for Gusev was found to contain
some rough-looking terrain in Mars Global Surveyor data, so the ellipse
was moved to gentler terrain slightly to the west.
Finally, there's Athabasca Valles in the Elysium Planitia,
or the "Plains of Elysium." "It is one of the youngest
outflow channels on Mars," said Golombek. "It's hundreds of
kilometers long with a catastrophic outflow channel, kind of like Ares
Valles where Pathfinder landed. Geologically, it's very young, just tens to
hundreds of millions of years old." The channel has been worn by
water and has young volcanics as well, making it a prime location to look
for hydrothermal deposits.