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Keeping Messenger On Course To Mercury

Messenger is the seventh mission in NASA's Discovery Program of lower cost, scientifically focused exploration projects. It will be the first spacecraft to orbit Mercury and only the second spacecraft that has been sent to Mercury.
Woodland Hills CA (SPX) Nov 11, 2004
Northrop Grumman's newest space navigation system is providing vital guidance and control information to NASA's Messenger spacecraft during its eight-year mission to Mercury, which began August 3 when it was launched from Cape Canaveral Air Force Station in Florida.

This is the first deployment into space for Northrop Grumman's scalable space inertial reference unit (scalable SIRU). The scalable SIRU is the next generation of Northrop Grumman's space inertial reference unit (SIRU (tm).

It will continuously provide inertial attitude, velocity and acceleration data to Messenger's attitude control system throughout the 5.8-billion mile space journey.

The new scalable SIRU, designed and produced by Northrop Grumman's Navigation and Space Sensors Division, uses the company's exclusive hemispherical resonator gyros (HRG).

The inherent high-reliability, high-performance, radiation tolerant features of the HRG and the dual redundant features of the scalable SIRU make this the ideal inertial reference unit for long-term (up to 15 years) space mission applications such as Messenger.

"Our scalable SIRU offers inherent precision performance and high reliability, which is central to this type of space-based mission," said Alexis Livanos, vice president and general manager of the Navigation and Space Sensors Division.

Northrop Grumman was awarded the contract for the Messenger mission by the Applied Physics Lab (APL) in Laurel, Md., part of Johns Hopkins University. APL manages the mission for NASA's Science Mission Directorate, built the spacecraft and operates Messenger during flight.

The science instruments on Messenger will give it the ability to provide far more data when it finally settles into orbit around Mercury.

Messenger's mission is to determine Mercury's composition; gather color images of its entire surface; map its magnetic field and measure the properties of its core; determine whether ice or other materials lie in its permanently shadowed regions; and study Mercury's atmosphere and magnetosphere.

Messenger is the seventh mission in NASA's Discovery Program of lower cost, scientifically focused exploration projects. It will be the first spacecraft to orbit Mercury and only the second spacecraft that has been sent to Mercury.

The first spacecraft, Mariner 10, flew past Mercury three times in 1974-1975 and gathered detailed information on less than half of the planet.

The HRG uses a thin-walled quartz shell that is energized by an electrical field to produce an imperceptible vibration pattern within itself. This pattern is electrically sensed and used to determine the gyro's output parameters.

The vibration is so minute that it creates virtually no internal stress and fatigue effects, leading to its unmatched reliability. Northrop Grumman is the exclusive producer of HRGs, which to date have accumulated more than 4,500,000 hours of operation in over 50 systems in space without a mission failure.

Northrop Grumman's SIRU was on the first Discovery mission, the Near Earth Asteroid Rendezvous (NEAR)-Shoemaker spacecraft that reached Eros in February 2000 and became the first spacecraft to land on an asteroid in 2001. It will also be on the Deep Impact Discovery mission scheduled to be launched in December 2004.

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Northrop Grumman's Navigation and Space Sensors Division
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Maneuver Puts Messenger On Track For 2005 Earth Flyby
Laurel MD (SPX) Sep 28, 2004
Messenger marked its 52nd day of flight operations with a burst from its thrusters, completing a maneuver on Sept. 24 that kept it on course for next summer's Earth flyby.



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