Opportunity Rover Begins Standing Up
January 28, 2004
NASA's Opportunity rover has untucked its front wheels and latched
its suspension system in place, key steps in preparing to drive off
its lander and onto martian soil.
Overnight tonight, mission controllers at NASA's Jet Propulsion
Laboratory, Pasadena, Calif., plan to try tilting the lander
platform down in the front by pressing the rear petal downward to
raise the back.
"What we want to do is lower the front edge by about 5 degrees,"
said JPL's Dr. Rick Welch, activity lead for preparing the rover for
roll-off. Plans call for driving off straight ahead, possibly as
early as overnight Sunday-Monday, if all goes well.
Meanwhile, halfway around Mars, Opportunity's twin, Spirit,
continues on the mend from a computer memory problem that struck it
a week ago. "Right now we're working to get complete control of the
vehicle, and we're still not quite there," said JPL's Jennifer
Trosper, mission manager. "If we're on the right track, we hope to
be back doing some science by early next week. If we're not on the
right track, it could take longer than that."
Opportunity's infrared sensing instrument, the miniature thermal
emission spectrometer, passed a health check last night. Scientists
plan to begin using it tonight. The instrument detects the
composition of rocks and soils from a distance. That information
will help scientists decide what targets to approach after
Opportunity drives off the lander.
Scientists and rover engineers are already discussing which specific
rocks within an outcropping near the lander will make the best
targets, said Dr. Jim Bell of Cornell University, Ithaca, N.Y., lead
scientist for the panoramic cameras on Opportunity and Spirit.
Details of the outcrop can be seen in a new a color-picture mosaic
Bell presented, the first portion of a full-circle panorama that has
been taken and partially transmitted.
Other new images show how Opportunity's airbags left detailed
impressions in the fine-textured soil as the spacecraft was rolling
to a stop in the small crater where it now sits. "These marks are
telling us about the physical properties of the material," Bell
said.
Some scientists believe that dark colored granules covering most of
the crater's surface were pressed down into an underlying layer of
powdery, lighter red material when the airbags hit. Others hold to a
theory that the dark granules are agglomerations that crumble into
the finer, lighter material when disturbed. After roll-off, soil
near the lander will be the rover's first target for close-up
examination with a microscope and two tools for detecting the
composition of the target. The soil at Opportunity's landing site
appears to have different properties than the soil at Spirit's
landing site, Bell said.
Opportunity has already validated predictions about the landing site
made on the basis of images and measurements taken by spacecraft
orbiting Mars, said JPL's Dr. Matt Golombek, a member of the rover
science team and co-chair of a steering committee that evaluated
potential landing sites for the rovers. The predictions included
that the region of Meridiani Planum where Opportunity landed would
be safe for landing, would be safe for rover driving, would have
very few rocks and would look unlike any place previously seen on
Mars.
"This bodes well for our ability to use remote sensing data in the
future for picking landing sites," Golombek said.
Engineers have been able to confirm a diagnosis that an unplanned
drawdown of battery power each night on Opportunity is due to a
heater on the rover's robotic arm. A switch designed to overrule
the heater's thermostatic control has not been working. "In the
near term, it's not providing any operational constraints," Welch
said.
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
http://athena.cornell.edu.
