NASA's Mars Orbiter Makes Successful Course Correction

The spacecraft fired all six main thrusters for 15 seconds onSaturday, Aug. 27. The engine burn followed a 30-second burn of sixsmaller thrusters, which settled propellant in the craft's fuel tankfor smoother flow. The spacecraft's orientation was adjusted prior tothe burns to point the engines in the proper direction for themaneuver. The spacecraft returned to the regular cruise-phase attitudeafter the trajectory adjustment.

"This maneuver accomplished two goals at once," said MarsReconnaissance Orbiter Deputy Mission Manager Dan Johnston of NASA'sJet Propulsion Laboratory, Pasadena, Calif. "It adjusted our trajectorytoward our Mars target point, and it gave us a valuable checkout of theorbit-insertion engines." The target point is 395 kilometers (245miles) above the surface of Mars.

Initial analysis of navigational data indicates this first flightpath correction successfully changed the spacecraft's velocity by theintended 7.8 meters per second (17.4 miles per hour). MarsReconnaissance Orbiter's velocity relative to the Sun is 32,856 metersper second (73,497 miles per hour).

The six main engines won't be used again until the craft arrives atMars. The next burn will last about 25 minutes. It will slow MarsReconnaissance Orbiter enough for the planet's gravity to capture thespacecraft into orbit. Each main engine produces approximately 38pounds of thrust. The three remaining opportunities scheduled forfine-tuning the trajectory before March will use smaller engines. Eachsmaller engine produces approximately five pounds of thrust.

"We intentionally designed the initial trajectory after launch witha bias in it so this first correction maneuver would be large enough tolet us use the main engines," Johnston said.

The next milestone for the mission is today. Mars ReconnaissanceOrbiter will turn on its instruments to check their condition. Thespacecraft was launched Aug. 12, and it is in excellent health. It hastraveled approximately 6 million kilometers (3.7 million miles) sincelaunch. It has 95.9 million kilometers (59.6 million miles) still tofly before reaching Mars.

The Mars Reconnaissance Orbiter mission will examine Mars inunprecedented detail from low orbit. Mission science objectives includestudying water distribution -- including ice, vapor or liquid – as wellas geologic features and minerals. It will also support future missionsto Mars by examining potential landing sites and by providing a relayfor communications back to Earth.

The mission is managed by JPL, a division of the CaliforniaInstitute of Technology, Pasadena, for the NASA Science MissionDirectorate. Lockheed Martin Space Systems, Denver, is the primecontractor for the project and built the spacecraft.

For information about the MRO on the Web, visit http://www.nasa.gov/mro . For information about NASA and agency programs on the Web, visit http://www.nasa.gov/home/index.html .