A NASA Discovery mission to conduct the first orbital study
of the innermost planet
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Simulating Space

Before MESSENGER is launched, the spacecraft team will test each component using various engineering methods to simulate aspects of the space environment - testing under normal Earth conditions may not reveal potential technical issues.

For example, the wire coils resting on the portable scaffold in this week's Webcam image are used to simulate the weaker magnetic fields MESSENGER will encounter at Mercury. Earth's magnetic field is 100 times stronger than Mercury's, so the MESSENGER Magnetometer (MAG) has two settings: one for testing at Earth and the other for science observations at Mercury. To make sure the instrument works properly at "Mercury" settings, engineers artificially lower the magnetic field at the MAG sensor during testing, by positioning these coils around the sensor and sending electric current through these coils to cancel (locally) Earth's magnetic field.

The Magnetometer blends with its surroundings in this view. Note the small silver dish at the end of the thin vertical black boom; the actual MAG sensor is inside the small yellowish cylinder just above the arrow labeled (G). In this orientation many other critical MESSENGER components are visible:

(A) phased-array antenna [one of 2]; (B) solar monitor for the X-Ray Spectrometer instrument; (C) hydrazine auxiliary fuel tank [under its protective cover]; (D) low-gain antenna; (E) helium pressurant tank; (F) star simulator [for testing Star Tracker cameras]; (G) Magnetometer boom [with Magnetometer in stowed position]; (H) low-gain antenna; (I) Digital Sun Sensor; (J) Fast Imaging Plasma Spectrometer [part of the Energetic Particle and Plasma Spectrometer instrument]; (K) umbilical harness [wiring]; (L) power system electronics; (M) solar panel simulator; (N) Inertial Measurement Unit; (O) thruster module.

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Last updated: October 24, 2003

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