Spirit Looks Down Into Crater After Reaching Rim

NASA’s Spirit has begun looking down into a crater it has been
approaching for several weeks, providing a view of what’s below the
surrounding surface.

Spirit has also been looking up, seeing stars and the first
observation of Earth from the surface of another planet. Its twin,
Opportunity, has shown scientists a "mother lode" of hematite now
considered a target for close-up investigation.

"It’s been an extremely exciting and productive week for both of the
rovers," said Spirit Mission Manager Jennifer Trosper at NASA’s Jet
Propulsion Laboratory, Pasadena, Calif.

Dr. Chris Leger, a rover driver at JPL, said, "The terrain has been
getting trickier and trickier as we’ve gotten close to the crater. The
slopes have been getting steeper and we have more rocks." Spirit has
now traveled a total of 335 meters (1,099 feet).

Spirit’s new position on the rim of the crater nicknamed "Bonneville"
offers a vista in all directions, including the crater interior. The
distance to the opposite rim is about the length of two football
fields, nearly 10 times the diameter of Opportunity’s landing-site
crater halfway around the planet from Spirit.

Initial images from Spirit’s navigation camera do not reveal any
obvious layers in "Bonneville’s" inner wall, but they do show
tantalizing clues of rock features high on the far side, science-team
member Dr. Matt Golombek of JPL said at a news briefing today. "This
place where we’ve just arrived has opened up, and it’s going to take
us a few days to get our arms around it."

Scientists anticipate soon learning more about the crater from
Spirit’s higher-resolution panoramic camera and the miniature thermal
emission spectrometer, both of which can identify minerals from a
distance. They will use that information for deciding whether to send
Spirit down into the crater.

From the crater rim and during martian nighttime earlier today, Spirit
took pictures of stars, including a portion of the constellation
Orion. Shortly before dawn four martian days earlier, it photographed
Earth as a speck of light in the morning twilight. The tests of rover
capabilities for astronomical observations will be used in planning
possible studies of Mars’ atmospheric characteristics at night. Those
studies might include estimating the amounts of dust and ice particles
in the atmosphere from their effects on starlight, said Dr. Mark
Lemmon, a science team member from Texas A&M University, College
Station.

Opportunity has been looking up, too. It has photographed Mars’
larger moon, Phobos, passing in front of the Sun twice in the past
week, and Mars’ smaller moon, Deimos, doing so once.

Opportunity’s miniature thermal emission spectrometer has taken
upward-looking readings of the atmospheric temperature at the same
time as a similar instrument, the thermal emission spectrometer on
NASA’s Mars Global Surveyor orbiter, took downward-pointed readings
while passing overhead. "They were actually looking directly along the
same path," said science team member Dr. Michael Wolff of the
Martinez, Ga., branch of the Space Science Institute, Boulder, Colo.
The combined readings give the first full temperature profile from the
top of Mars’ atmosphere to the surface."

When pointed at the ground, Opportunity’s miniature thermal emission
spectrometer has checked the abundance of hematite in all directions
from the rover’s location inside its landing-site crater. This
mineral, in its coarse-grained form, usually forms in a wet
environment. Detection of hematite from orbit was the prime factor in
selection of the Meridiani Planum region for Opportunity’s landing
site.

"The plains outside our crater are covered with hematite," said Dr.
Phil Christensen of Arizona State University, Tempe, lead scientist
for the instrument. "The rock outcrop we’ve been studying has some
hematite. Parts of the floor of the crater, interestingly enough,
have virtually none." The pattern fits a theory that the crater was
dug by an impact that punched through a hematite-rich surface layer,
he said. One goal for Opportunity’s future work is to learn more
about that surface layer to get more clues about the wet past
environment indicated by sulfate minerals identified last week in the
crater’s outcrop.

Christensen said that before Opportunity drives out of the crater in
about 10 days, scientists plan to investigate one area on the inner
slope of the crater that he called "the mother lode of hematite."
JPL, a division of the California Institute of Technology in Pasadena,
manages the Mars Exploration Rover project for NASA’s Office of Space
Science, Washington, D.C. Images and additional information about the
project are available from JPL at

http://marsrovers.jpl.nasa.gov

and from Cornell University at