Mars Reconnaissance Orbiter Tweaks Course, Passes Halfway Point

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Guy Webster (818) 354-6278
Jet Propulsion Laboratory, Pasadena, Calif.

Dwayne Brown (202) 358-1726
NASA Headquarters, Washington

News Release: 2005-164 November 18, 2005

Mars-Bound Nasa Craft Tweaks Course, Passes Halfway Point

NASA's Mars Reconnaissance Orbiter successfully fired six engines
for about 20 seconds today to adjust its flight path in advance of
its March 10, 2006, arrival at the red planet.

Since its Aug. 12 launch, the multipurpose spacecraft has covered
about 60 percent of the distance for its trip from Earth to Mars.
It will fly about 40-million kilometers (25-million miles) farther
before it enters orbit around Mars. It will spend half a year
gradually adjusting the shape of its orbit, then begin its science
phase. During that phase, it will return more data about Mars than
all previous missions combined. The spacecraft has already set a
record transmission rate for an interplanetary mission, successfully
returning data at 6 megabits per second, fast enough to fill a CD-ROM
every 16 minutes.

"Today's maneuver mainly increases the speed to bring us to the target
point at just the right moment," said Tung-Han You, chief of the Mars
Reconnaissance Orbiter navigation team at NASA's Jet Propulsion
Laboratory, Pasadena, Calif. The intended nudge in velocity is 75
centimeters per second (less than 2 miles per hour). The spacecraft's
speed relative to the sun is about 27 kilometers per second (61,000
miles per hour).

Four opportunities for course adjustments were planned into the
schedule before launch. Today's, the second, used only the
trajectory-correction engines. Each engine produces about 18 newtons
(4 pounds) of thrust. The first course adjustment, on Aug. 27,
doubled as a test of the six main engines, which produce nearly eight
times as much thrust. Those main engines will have the big job of
slowing the spacecraft enough to be captured into orbit when it reaches

Mars. The next scheduled trajectory adjustment, on Feb. 1, 2006, and
another one 10 days before arrival will be used, if necessary,
for fine tuning, said JPL's Allen Halsell, the mission's deputy
navigation chief.

The Mars Reconnaissance Orbiter mission will examine Mars in
unprecedented detail from low orbit. Its instrument payload will
study water distribution -- including ice, vapor or liquid -- as well
as geologic features and minerals. The orbiter will also support
future missions to Mars by examining potential landing sites and by
providing a high-data-rate relay for communications back to Earth.

The mission is managed by JPL, a division of the California Institute
of Technology, Pasadena, for the NASA Science Mission Directorate.
Lockheed Martin Space Systems, Denver, is the prime contractor for
the project and built the spacecraft.

For information about the Mars Reconnaissance Orbiter 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 .

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