Launched to Mars folded and crouched in its landing cocoon, NASA's Opportunity rover has nearly completed the complex blossoming into a road-ready vehicle and could take its first drive onto the Red Planet's surface Saturday night.

An artist's concept shows a Mars Exploration Rover on the move. Credit: NASA/JPL

The post-landing transformation began soon after touchdown last Sunday morning as the lander base opened and the rover extended its solar panels and camera mast. The lollipop-shaped main communications antenna began service earlier this week, and the past few days have been dedicated to deploying the wheels and suspension system.

Opportunity was jacked up Wednesday, allowing the front two wheels to unfold and the rocker-bogie suspension system to lock into place. The rear wheels extended Thursday to give the vehicle the desired wheelbase length. The center wheels were scheduled to be lowered into position early Friday.

Also Friday morning, the multi-jointed arm holding the science instruments for close-up examination of the Martian soil and rocks was to be unlatched from its launch location and stowed in the "drive" position.

Controllers say if all continues to go as smoothly as the past week, Opportunity will make a 10-foot drive off the lander base and onto the small crater floor Saturday night/Sunday morning to begin its exploration mission of Meridiani Planum.

To help the rover's journey off the lander, which engineers consider the riskiest drive that the craft will take on Mars, Mission Control on Thursday commanded a further retraction of the airbags on the back side of the lander and then forced the rear petal downward. This was designed to prop up the rear of the lander, thereby tilting the base forward for Opportunity to drive off.

"What this did is drive our front edge lower," said mission manager Matt Wallace. "The tips of the egress aid (a reinforced fabric ramp) are now in the soil. That makes egress look perfect. It's going to be an easy ride."

The Spirit rover's drive off its lander earlier this month was complicated by airbags hampering the preferred path. Unable to simply roll straight onto the surface, Spirit had to make a 115-degree turn on the base to reach an alternate driveway. Opportunity has no such obstacle.

On the science agenda Thursday, Opportunity used the Mini-Thermal Emission Spectrometer to survey the mineral composition of the immediate surroundings, including the rock outcrop. Opportunity did not return the data from those observations before going to sleep for the Martian night, but may Friday, officials reported.

The Spirit rover located half-a-world away was receiving commands from Earth Thursday to resume its scientific work at Gusev Crater. Panoramic camera images of nearby rocks were to be snapped.

Also, controllers were hoping to receive a playback of Mossbauer Spectrometer and Alpha Particle X-ray Spectrometer data obtained during last week's study of a pyramid-shaped rock, nicknamed Adirondack. The information was collected but not yet relayed to Earth when Spirit's computer troubles began.

The Jet Propulsion Laboratory reported several attempts to get a full trace of the rover's problem have only partially succeeded. The engineers might choose to reformat the rover's flash memory in the next few days.

"We know we still have some engineering work to do, but we think we understand the problem well enough to do science in parallel with that work," mission manager Jennifer Trosper said.

There was no Mars rover status news conference Thursday. The next briefing is scheduled for Friday at 12 noon EST (1700 GMT).

Video coverage for subscribers only:
   VIDEO: OPPORTUNITY STAND UP & WHEEL DEPLOY W/NARRATION QT
   VIDEO: ALL THE IMAGES RELEASED WEDNESDAY WITH NARRATION QT
   VIDEO: COMPARE VIKING, PATHFINDER & ROVER LANDING SITES QT
   VIDEO: WEDNESDAY'S MARS ROVER STATUS NEWS CONFERENCE QT

   VIDEO: LIVE LANDING COVERAGE FROM ENTRY TO TOUCHDOWN QT
   VIDEO: OPPORTUNITY'S FIRST IMAGES RECEIVED ON EARTH QT
   VIDEO: FIRST COLOR IMAGERY FROM OPPORTUNITY UNVEILED QT
   VIDEO: SCIENCE LEADER NARRATES THE FIRST BATCH OF IMAGES QT

   MORE: PREVIOUS MISSION COVERAGE!
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