The spacecraft shot through a breezy, cloud-laced mid- afternoon sky atop a Delta II launch vehicle on the second day of the primary launch period with new onboard software to guard against overcharging the spacecraft's battery. The orbiter team tested the new software using the Mars Polar Lander spacecraft at Kennedy Space Center, FL, as a testbed. Mars Polar Lander, which will join Mars Climate Orbiter at Mars in December 1999, is currently being processed for launch on January 3, 1999.

Sixty seconds after liftoff, the four solid-rocket boosters were jettisoned, two at a time, followed by first-stage separation and second-stage engine ignition. The second-stage burn lasted approximately 11 minutes, 22 seconds, placing the spacecraft in a low-Earth orbit at about 189 kilometers (117 miles) above Earth's surface.

Third-stage separation occurred at approximately 2:26 p.m. EST, followed by a burn of the third-stage engine for 88 seconds. Once out of Earth's gravitational grasp, the orbiter was jettisoned from the third stage using the spacecraft's onboard thrusters to remove all remaining motion. Four minutes later, the spacecraft's solar arrays were unfolded and pointed toward the Sun for power. NASA's Deep Space Network complex near Canberra, Australia, acquired the orbiter's signal at 2:45 p.m. EST. Spacecraft controllers at Lockheed Martin Astronautics in Denver, CO, and at the Jet Propulsion Laboratory in Pasadena, CA, are now assessing the spacecraft's initial performance.

Now on its way to Mars, the Climate Orbiter will rely on its low-gain and medium-gain antennas for communications with Earth during the first half of the journey to Mars. Ground-controllers will track the spacecraft 24 hours a day during the first week of cruise, then reduce tracking time to 12 hours a day using 34- meter (112-foot) antennas of the Deep Space Network. Twelve days into flight, one of the spacecraft's science instruments, the Pressure Modulator Infrared Radiometer, will be powered on and acclimated to the environment of space.

The first trajectory correction maneuver to remove errors in the spacecraft's flight path introduced at the time of launch will be performed 10 days into the cruise phase, on December 21, 1998. That thruster firing will be the largest and longest of all four trajectory correction maneuvers, lasting about 15 to 20 minutes and changing the spacecraft's velocity by about 30 meters per second (67 miles per hour).

Mars Climate Orbiter and Mars Polar Lander are the second set of spacecraft to be launched in NASA's long-term program of robotic exploration of Mars.

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• Space Missions
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• Phoenix (spacecraft)
• Multistage rocket
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