The Mars-bound Curiosity rover will be begin steering toward the red planet during a lengthy thruster firing Wednesday, erasing the launch trajectory's deliberate aim away from the destination.

This is an artist's concept of NASA's Mars Science Laboratory spacecraft during its cruise. The spacecraft includes a disc-shaped cruise stage (on the left) attached to the aeroshell that contains the rover and descent stage. Credit: NASA/JPL-Caltech

The United Launch Alliance Atlas 5 rocket dispatched the $2.5 billion Mars Science Laboratory mission from Cape Canaveral on Nov. 26. (Read our call of the launch)

Just like all planetary launches, the rocket actually fired the payload off-center from the target on a path to miss Mars by 38,000 miles to ensure the Centaur upper stage that is following the spacecraft won't hit the planet. The rocket motor wasn't subjected to the thorough cleaning to prevent Earth's microbes from contaminating Mars, thus the purposeful effort to prevent an impact.

The car-sized rover, packed inside the protective descent capsule, will use 8 thrusters located on the donut-shaped cruise ring atop the spacecraft to conduct the trajectory correction maneuver Wednesday starting at 6 p.m. EST (2300 GMT).

The first opportunity to perform the post-launch adjustment was available 15 days into the mission. But flight controllers opted to cancel that plan and wait six weeks before doing it now.

Seen as the largest maneuver the spacecraft will carry out during its 8.5-month trek from Earth to Mars, the thrusters are fired in a pre-programmed sequence over the span of 175 minutes to impart a velocity change of about 12.3 miles per hour.

"We are well into cruise operations, with a well-behaved spacecraft safely on its way to Mars," said Arthur Amador, Mars Science Lab's cruise mission manager at NASA's Jet Propulsion Laboratory in Pasadena. "After this trajectory correction maneuver, we expect to be very close to where we ultimately need to be for our entry point at the top of the Martian atmosphere."

The mission's trajectory -- as spelled out before launch -- included windows for 6 correction maneuvers. The last could occur as late as 9 hours before landing to fix any errors prior to atmospheric entry.

A burn in June will eye the precise corridor to the landing site where scientists want to send the rover within Gale Crater to determine if the area with its layered sedimentary landscape and apparent watery past was ever hospitable to life. The landing zone is a relatively small ellipse just 12.4 miles wide and 15.5 miles long -- a mere one-third the size of previous Mars rovers.

The $2.5 billion mission is headed for a late-night landing (California time) August 5 between 10 and 10:30 p.m. PDT (1 and 1:30 a.m. EDT Aug. 6) in Gale Crater.

As of Saturday, the spacecraft has traveled 73 million miles of its 352-million-mile trek to Mars, moving at 9,500 mph relative to Earth and at 69,500 mph relative to the Sun.

Mars Science Lab is spinning at 2.04 rotations per minute, communicating with Earth at a transmission rate of 2 kilobits per second and producing 780 watts of power from the cruise ring's solar arrays.

And the mission's Radiation Assessment Detector continues collecting data on the way to Mars.

Additional coverage for subscribers:
VIDEO: THE FULL LAUNCH EXPERIENCE PLAY | HI-DEF
VIDEO: ATLAS 5 ROCKET LAUNCHES MARS SCIENCE LAB PLAY | HI-DEF
VIDEO: ONBOARD CAMERA VIEW OF NOSE CONE JETTISON PLAY | HI-DEF
VIDEO: ONBOARD CAMERA VIEW OF THE STAGING EVENT PLAY | HI-DEF
VIDEO: ONBOARD VIEW OF ROCKET RELEASING MSL PLAY
VIDEO: LAUNCH DECLARED A SUCCESS PLAY

VIDEO: LAUNCH REPLAYS: OUR VIEW OF LIFTOFF PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: VAB ROOF PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: PATRICK AFB PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: SOUTH OF THE PAD PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: THE BEACH TRACKER PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: SHUTTLE PAD CAMERA PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: SHUTTLE WATER TOWER PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: TRACKER WEST OF THE PAD PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: CLOSE-UP ON UMBILICALS PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: COMPLEX 41 VIF PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: THE PRESS SITE PLAY | HI-DEF

VIDEO: PRE-LAUNCH INTERVIEW WITH PROJECT MANAGER PLAY | HI-DEF
VIDEO: NARRATED PREVIEW OF ATLAS 5 ASCENT PROFILE PLAY | HI-DEF
VIDEO: ROCKET'S LAUNCH CAMPAIGN HIGHLIGHTS PLAY | HI-DEF
VIDEO: MSL'S LAUNCH CAMPAIGN HIGHLIGHTS PLAY | HI-DEF
VIDEO: SPACECRAFT CLEANROOM TOUR PLAY | HI-DEF

VIDEO: ATLAS ROCKET ROLLS OUT TO LAUNCH PAD PLAY | HI-DEF
VIDEO: TIME-LAPSE VIEWS OF ROCKET ROLLOUT PLAY | HI-DEF

VIDEO: THE PRE-LAUNCH NEWS CONFERENCE PLAY
VIDEO: CURIOSITY ROVER SCIENCE BRIEFING PLAY
VIDEO: LOOKING FOR LIFE IN THE UNIVERSE PLAY
VIDEO: WHAT WE KNOW ABOUT THE RED PLANET PLAY
VIDEO: ROBOTICS AND HUMANS TO MARS TOGETHER PLAY

VIDEO: PREVIEW OF ENTRY, DESCENT AND LANDING PLAY | HI-DEF
VIDEO: PREVIEW OF CURIOSITY ROVER EXPLORING MARS PLAY | HI-DEF
VIDEO: A FLYOVER OF THE GALE CRATER LANDING SITE PLAY | HI-DEF

VIDEO: NUCLEAR GENERATOR HOISTED TO ROVER PLAY | HI-DEF
VIDEO: MARS SCIENCE LAB MOUNTED ATOP ATLAS 5 PLAY | HI-DEF
VIDEO: MOVING MSL TO ATLAS ROCKET HANGAR PLAY | HI-DEF
VIDEO: SPACECRAFT PLACED ABOARD TRANSPORTER PLAY | HI-DEF

VIDEO: APPLYING MISSION LOGOS ON THE FAIRING PLAY | HI-DEF
VIDEO: MSL ENCAPSULATED IN ROCKET'S NOSE CONE PLAY | HI-DEF
VIDEO: FINAL LOOK AT SPACECRAFT BEFORE SHROUDING PLAY | HI-DEF

VIDEO: HEAT SHIELD INSTALLED ONTO SPACECRAFT PLAY | HI-DEF
VIDEO: BEAUTY SHOTS OF SPACECRAFT PACKED UP PLAY | HI-DEF
VIDEO: ATTACHING THE RING-LIKE CRUISE STAGE PLAY | HI-DEF
VIDEO: PARACHUTE-EQUIPPED BACKSHELL INSTALLED PLAY | HI-DEF
VIDEO: SKYCRANE AND CURIOSITY MATED TOGETHER PLAY | HI-DEF

VIDEO: TWO-HALVES OF ROCKET NOSE CONE ARRIVES PLAY | HI-DEF
VIDEO: CENTAUR UPPER STAGE HOISTED ATOP ATLAS PLAY | HI-DEF
VIDEO: FINAL SOLID ROCKET BOOSTER ATTACHED PLAY | HI-DEF
VIDEO: FIRST OF FOUR SOLID BOOSTERS MOUNTED PLAY | HI-DEF
VIDEO: FIRST STAGE ERECTED ON MOBILE LAUNCHER PLAY | HI-DEF
VIDEO: STAGES DRIVEN FROM HARBOR TO THE ASOC PLAY | HI-DEF
VIDEO: ROCKET ARRIVES ABOARD SEA-GOING VESSEL PLAY | HI-DEF

VIDEO: STOWING ROVER'S INSTRUMENTED ROBOT ARM PLAY | HI-DEF
VIDEO: DEPLOYING CURIOSITY'S SIX WHEELS ON EARTH PLAY | HI-DEF
VIDEO: MMRTG PUT BACK INTO STORAGE AT SPACEPORT PLAY | HI-DEF
VIDEO: NUCLEAR GENERATOR FIT-CHECK ON THE ROVER PLAY | HI-DEF
VIDEO: ROVER'S NUCLEAR POWER SOURCE ARRIVES PLAY | HI-DEF
VIDEO: SPIN-TESTING THE RING-LIKE CRUISE STAGE PLAY | HI-DEF

VIDEO: UNCOVERING CURIOSITY ROVER IN CLEANROOM PLAY | HI-DEF
VIDEO: UNVEILING THE ROCKET-POWERED SKYCRANE PLAY | HI-DEF
VIDEO: UNBOXING THE ROVER FROM SHIPPING CRATE PLAY | HI-DEF
VIDEO: ROVER HAULED FROM RUNWAY TO PHSF FACILITY PLAY | HI-DEF
VIDEO: MARS ROVER ARRIVES AT KENNEDY SPACE CENTER PLAY | HI-DEF

VIDEO: DESCENT WEIGHTS INSTALLED ON BACKSHELL PLAY | HI-DEF
VIDEO: SOLAR ARRAY PANELS ATTACHED TO CRUISE RING PLAY | HI-DEF
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