Above is an artist’s conception of the spacecraft during its cruise phase between launch and final approach to Mars. It includes a disc-shaped cruise stage (on the left) attached to the aeroshell. The spacecraft’s rover (Curiosity) and descent stage are tucked inside the aeroshell.

The maneuver will use a choreographed sequence of firings of eight thruster engines during a period of about 175 minutes beginning at 6 p.m. EST. It will redirect the spacecraft more precisely toward Mars to land at Gale Crater. The trajectory resulting from the mission’s November 26, 2011, launch intentionally misses Mars to prevent the upper stage of the launch vehicle from hitting the planet. That upper stage, which separated from the spacecraft about 44 minutes after launch, was not cleaned the way the spacecraft itself was to protect Mars from Earth’s microbes.

The maneuver is designed to impart a velocity change of 5.5 meters per second.

“We are well into cruise operations, with a well-behaved spacecraft safely on its way to Mars,” said Mars Science Laboratory Cruise Mission Manager Arthur Amador, of NASA’s Jet Propulsion Laboratory in Pasadena, California. “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 Mars Science Laboratory mission will use its car-size rover, Curiosity, to investigate whether the selected region on Mars inside Gale Crater has offered environmental conditions favorable for supporting microbial life and for preserving clues about whether life existed.