January 9, 2004
Rover Seeks
Best Route Off Platform and Around Surface
While NASA engineers consider the best
way to get Mars Explorer Spirit successfully around an airbag
partially blocking its path, the rover is using infrared and
other sensing devices to determine the most interesting locations
within the Gusev Crater as well as the safest path to get to
them.
A tug on airbag tendons by the airbag retraction
motor Thursday evening did not lower puffed up portions of airbag
material that are a potential obstacle to driving the rover straight
forward to exit the lander. The most likely path for driving
off will be to turn 120 degrees to the right before rolling off.
"This is something we have practiced many times. We are
very comfortable doing it," JPL's Matt Wallace, mission
manager for the Mars Exploration Rover project, said.
The earliest scenario for getting the rover
off the lander, if all goes smoothly, is Spirit's 13th or 14th
day on Mars, Jan. 16 or 17.
"We're proceeding in a measured, temperate
way," JPL's Peter Theisinger, project manager , said. "This
is a priceless asset. It is fully functioning. It is sitting
in a beautiful scientific target. We're not going to take any
inappropriate risks."
Martian Landscape Showing
Airbag Near Rover
Click
for larger image
Courtesy NASA/JPL/Cornell
Traces of carbonate minerals showed up
in the rover's first survey of the site with its infrared sensing
instrument, called the miniature thermal emission spectrometer
or Mini-TES. Carbonates form in the presence of water, but it's
too early to tell whether the amounts detected come from interaction
with water vapor in Mars' atmosphere or are evidence of a watery
local environment in the past, scientists emphasized.
"We came looking for carbonates. We
have them. We're going to chase them," Dr. Phil Christensen
of Arizona State University, Tempe, leader of the Mini-TES team,
said. Previous infrared readings from Mars orbit have revealed
a low concentration of carbonates distributed globally. Christensen
has interpreted that as the result of dust interaction with atmospheric
water. First indications are that the carbonate concentration
near Spirit may be higher than the Mars global average.
After the rover drives off its lander platform,
infrared measurements it takes as it explores the area may allow
scientists to judge whether the water indicated by the nearby
carbonates was in the air or in a suspected ancient lake.
"The beauty is we know how to find
out," Dr. Steve Squyres of Cornell University, Ithaca, N.Y.,
principal investigator for the mission, said. "Is the carbonate
concentrated in fluffy dust? That might favor the atmospheric
hypothesis. Is it concentrated in coarser material? That might
favor the water hypothesis."
Scientists and engineers will also use
the infrared data to plot a safe course for the rover take free
of loose dust.
Spirit accomplished a key step late Thursday
in preparing for rolling off the lander. In anticipation, the
flight team at NASA Jet Propulsion Laboratory in Pasadena, Calif.,
played Bob Marley's "Get Up, Stand Up" as wake-up music
for the sixth morning on Mars. In the following hours, the rover
was raised by a lift mechanism under its belly, and its front
wheels were fully extended. Then the rover was set back down,
raised again and set down again to check whether suspension mechanisms
had latched properly.
Pictures returned from the rover's navigation
camera and front hazard-identification camera, plus other data,
confirmed that it was a success.
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