An artist's concept of Spirit driving off its lander. Credit: NASA/JPL

The command ordering the Spirit rover to roll off its lander and onto the surface of Mars was transmitted at 3:21:30 a.m. EST.

"Flight, I have alpha, alpha, charlie, tango, underscore, romeo, two-one, niner-six, decimal alpha, decimal zero, zero in the radiation cue," a controller informed flight director Chris Lewicki when the instructions were ready to go.

"OK, alpha, alpha, charlie, tango, underscore, romeo, two-one, niner-six, decimal alpha, decimal zero, zero," Lewicki confirmed. "This is our command (for) the most significant 3-meter drive in recorded history." The control team laughed. "That's a good readback, you're clear to radiate."

"On my mark," the controller replied. "Three, two, one, mark!"

And with that, coded instructions began racing toward Mars, more than 100 million miles away, where the Spirit lander sat patiently atop its lander, poised for roll off.

It would take an hour and a half for the rover to complete its slow move off the lander's northwest egress aid and onto the surface, to find the sun, reorient its high-gain antenna and radio telemetry back to the Jet Propulsion Laboratory, confirming its initial foray.

As the waiting began, mission manager Jennifer Trosper cued up the theme song from the TV series "Rawhide" and the familiar refrain "rollin', rollin', rollin'" blared out in the flight control room."

The Spirit rover's view forward as it drives on the surface of Mars today. Credit: NASA/JPL See larger image here

It was the moment the engineers and scientists had been waiting for since Spirit bounced to a successful landing on Mars Jan. 3.

"This is a night that is extraordinarily rich in significance for all of us, certainly for those of us on the science team and I know for everybody here as well," principal investigator Steve Squyres told the team. "When I first presented this long-term (exploration) plan to the public a couple of days ago, I said it was rich in scientific potential. But I also said it was going to be a shared adventure unlike any other in human history. When I said that, what I meant for the press and the public was that it was an adventure we would share with the whole world.

"But on a much deeper and more personal level, it's an adventure that I'm just incredibly proud to share with the people in this room and this team. And so, when we see that picture (showing the lander in the background) and everybody starts getting all choked up and running around hugging people again, please forgive me. Thanks."

Finally, at 4:53 a.m., a controller called out: "We have carrier in lock," meaning NASA's Deep Space Network tracking antennas once again were receiving a signal from Spirit. Five minutes later, a controller reported telemetry confirmed that Spirit had, in fact, moved three meters, or about 9.8 feet from its starting point atop the lander.

"Sounds like it was a nice trip," Lewicki said. "All we need now are the pictures."

Then, two minutes later, the first grainy black-and-white thumbnail image from a rear-facing navigation camera came in, clearly showing the lander, perched atop its crumpled airbags, in the background. Spirit was finally on the surface of Mars and the flight team burst into cheers and applause. Squyres embraced Lewicki and science manager John Callas gave Trosper a bouquet of flowers.

Spirit's view looking back at the lander. Credit: NASA/JPL See larger image here

"That's a big relief!" said Rob Manning, the engineer who oversaw Spirit's entry, descent and landing 12 days ago. "We're on Mars. Spirit has landed."

Project manager Pete Theisinger held up a T-shirt with an image of the rover on one side, along with the words "My other car is on Mars!!!" Then someone cued up the song "Who Let The Dogs Out?"

A few minutes later, a higher resolution image came in, clearly showing Spirit's two back wheels and ruddy tire tracks leading back to the lander's egress aids. Martian soil could be seen clumped up on the rear left wheel as the team once again burst into cheers.

"Our wheels are finally dirty," Manning observed. "This is very exciting. What a relief."

Video coverage for subscribers only:
   VIDEO: FLIGHT DIRECTOR CHRIS LEWICKI GIVES OK FOR DRIVE QT
   VIDEO: MOMENT WHEN DRIVE ONTO SURFACE IS CONFIRMED QT
   VIDEO: CELEBRATIONS AT FIRST VIEW OF EMPTY LANDER BASE QT
   VIDEO: IMAGES RECEIVED FROM SPIRIT AFTER THE ROLL-OFF QT
   VIDEO: ANIMATION OF SPIRIT'S TURNS & DRIVE FROM LANDER QT
   VIDEO: TODAY'S NEWS CONFERENCE AFTER SPIRIT'S DRIVE QT
   VIDEO: MISSION CONTROL TEAM BRIEFED ON SCIENCE PLAN QT
   SUBSCRIBE NOW