The Mars Exploration Rover Opportunity will be driving off its lander even earlier than envisioned yesterday. The $400 million craft is now slated to reach the surface by early Saturday morning (U.S. time).

"We've had a good couple of days on Opportunity. As a result, we are a little bit ahead of schedule," rover systems engineer Daniel Limonadi said at the status briefing underway right now at the Jet Propulsion Laboratory.

In the just-completed workday that occurred overnight (U.S. time), the rover's center wheels were released and the science arm was unlatched and moved to its stowed position for the drive off the lander. Tonight, the Mossbauer Spectrometer and Alpha Particle X-ray Spectrometer instruments on the end of the rover's arm are undergoing testing.

"That's both a functional check to make sure everything still works after the pyro fire from the (arm) release we did today and also a nighttime calibration for both of those instruments," Limonadi said.

On the Friday night (U.S. time) workday, the final umbilical linking the landing base and the rover will be cut and then Opportunity will move a tiny bit to ensure its drive system is functioning. If all goes well, the rover will drive onto the surface early Saturday morning (Eastern Standard Time).

Limonadi says Mission Control will send Opportunity the command to make the autonomous drive at about 3:30 a.m. EST (0830 GMT). Data to confirm the 10-foot drive has occurred will be received on Earth around 6 a.m. EST (1100 GMT).

The departure from the lander is occurring two days ahead of schedule and five days ahead of the timeline that Spirit took.

We will be updating this page with live reports Saturday morning as Opportunity reaches the Martian surface to begin roving around Meridiani Planum.

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   VIDEO: 3-D MODEL OF OPPORTUNITY'S LANDING SITE CRATER QT
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