NASA’s Spirit has begun pivoting atop its lander
platform on Mars, and the robot’s human partners have
announced plans to send it toward a crater, then toward some
hills, during the mission.
Determining exactly where the spacecraft landed, in the
context of images taken from orbit, has given planners a
useful map of the vicinity. After Spirit drives off its
lander and examines nearby soil and rocks, the scientists and
engineers managing it from NASA’s Jet Propulsion Laboratory,
Pasadena, Calif., intend to tell it to head for a crater that
is about 250 meters (about 270 yards) northeast of the
lander.
“We’ll be careful as we approach. No one has ever driven up
to a martian crater before,” said Dr. Steve Squyres of
Cornell University, Ithaca, N.Y., principal investigator for
the science instruments on Spirit and on its twin Mars
Exploration Rover, Opportunity.
The impact that dug the crater about 200 meters (about 220
yards) wide probably flung rocks from as deep as 20 to 30
meters (22 to 33 yards) onto the surrounding surface, where
Spirit may find them and examine them. “It will provide a
window into the subsurface of Mars,” Squyres said.
This zoomed-in overhead view of the Mars Exploration Rover Spirit’s estimated landing site and surrounding area shows the rover’s potential “itinerary.” Scientists and engineers plan to drive the rover approximately 250 meters (820 feet) from the green point to the rim of a nearby crater measuring 192 meters (630 feet) in diameter. They then plan to drive toward the east hills, the tops of which measure 2-3 kilometers (1-2 miles) away from the rover’s estimated landing site. This image is a composite of images taken by the camera on Mars Global Surveyor and the descent image motion estimation system camera located on the bottom of the rover’s lander. Image Credit: NASA/JPL/MSSS
Craters come in all sizes. The main scientific goal for
Spirit is to determine whether the Connecticut-sized Gusev
Crater ever contained a lake. Taking advantage of the nearby
unnamed crater for access to buried deposits will add to what
Spirit can learn from surface materials near the lander.
After that, if all goes well, the rover will head toward a
range of hills about 3 kilometers (2 miles) away for a look
at rocks that sit higher than the landing neighborhood’s
surface. That distance is about five times as far as NASA’s
mission-success criteria for how far either rover would
drive. The highest hills in the group rise about 100 meters
(110 yards) above the plain.
“I cannot tell you we’re going to reach those hills,” Squyres
said. “We’re going to go toward them.” Getting closer would
improve the detail resolved by Spirit’s panoramic camera and
by the infrared instrument used for identifying minerals from
a distance.
First, though, comes drive-off. Overnight Monday to Tuesday,
Spirit began rolling. It backed up 25 centimeters (10
inches), turned its wheels and pivoted 45 degrees.
“The engineering team is just elated that we’re driving,”
said JPL’s Chris Lewicki, flight director. “We’ve cut loose
our ties and we’re ready to rove.” After two more pivots,
for a total clockwise turn of 115 degrees, Spirit will be
ready for driving onto the martian surface very early
Thursday morning, according to latest plans.
Engineers and scientists have determined where on the martian
surface the lander came to rest. NASA’s Mars Odyssey orbiter
was used in a technique similar to satellite-based global
positioning systems on Earth to estimate the location of the
landing site, said JPL’s Joe Guinn of the rover mission’s
navigation team. Other researchers correlated features seen
on the horizon in Spirit’s panoramic views with hills and
craters identifiable in images taken by Mars Global Surveyor
and Odyssey. “We’ve got a tremendous vista here with all
kinds of features on the horizon,” said JPL’s Dr. Tim Parker,
landing site-mapping geologist.
The spacecraft came to rest only about 250 to 300 meters (270
to 330 yards) southeast of its first impact. Transverse
rockets successful slowed horizontal motion seconds before
impact, said JPL’s Rob Manning, who headed development of the
entry, descent and landing system. The spacecraft, encased in
airbags, was just 8.5 meters (27.9 feet) off the ground when
its bridle was cut for the final freefall to the surface. It
first bounced about 8.4 meters (27.6 feet) high, then bounced
27 more times before stopping.
Analysis of Spirit’s landing may aid in minor adjustments for
Opportunity, on track for landing on the opposite side of
Mars on Jan. 25 EST.
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. For more
information about NASA and the Mars mission on the Internet,
visit:
Additional information about the project is available from
NASA’s JPL at:
http://marsrovers.jpl.nasa.gov
For information from Cornell University, visit:
http://athena.cornell.edu
