NASA's Mars Orbiter Makes Successful Course Correction
Artist's concept of Mars Reconnaissance Orbiter en route to Mars. Image credit: NASA/JPL
August 30, 2005
NASA's Mars Reconnaissance Orbiter successfully tested its main engines
by making a successful trajectory adjustment for reaching the red planet
on March 10, 2006.
The spacecraft fired all six main thrusters for 15 seconds on Saturday,
Aug. 27. The engine burn followed a 30-second burn of six smaller thrusters,
which settled propellant in the craft's fuel tank for smoother flow. The
spacecraft's orientation was adjusted prior to the burns to point the engines
in the proper direction for the maneuver. The spacecraft returned to the regular
cruise-phase attitude after the trajectory adjustment.
"This maneuver accomplished two goals at once," said Mars Reconnaissance Orbiter
Deputy Mission Manager Dan Johnston of NASA's Jet Propulsion Laboratory, Pasadena,
Calif. "It adjusted our trajectory toward our Mars target point, and it gave us a
valuable checkout of the orbit-insertion engines." The target point is 395 kilometers
(245 miles) above the surface of Mars.
Initial analysis of navigational data indicates this first flight path correction
successfully changed the spacecraft's velocity by the intended 7.8 meters per second
(17.4 miles per hour). Mars Reconnaissance Orbiter's velocity relative to the Sun is
32,856 meters per second (73,497 miles per hour).
The six main engines won't be used again until the craft arrives at Mars. The next
burn will last about 25 minutes. It will slow Mars Reconnaissance Orbiter enough for
the planet's gravity to capture the spacecraft into orbit. Each main engine produces
approximately 38 pounds of thrust. The three remaining opportunities scheduled for
fine-tuning the trajectory before March will use smaller engines. Each smaller engine
produces approximately five pounds of thrust.
"We intentionally designed the initial trajectory after launch with a bias in it so
this first correction maneuver would be large enough to let us use the main engines,"
Johnston said.
The next milestone for the mission is today. Mars Reconnaissance Orbiter will turn
on its instruments to check their condition. The spacecraft was launched Aug. 12,
and it is in excellent health. It has traveled approximately 6 million kilometers
(3.7 million miles) since launch. It has 95.9 million kilometers (59.6 million miles)
still to fly before reaching Mars.
The Mars Reconnaissance Orbiter mission will examine Mars in unprecedented detail from
low orbit. Mission science objectives include studying water distribution -- including
ice, vapor or liquid – as well as geologic features and minerals. It will also support
future missions to Mars by examining potential landing sites and by providing a 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 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 .
Guy Webster (818) 354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
Dolores Beasley (202) 358-1753
NASA Headquarters, Washington, D.C.
2005-140
