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An Instrumental Milestone

On October 3, the Gamma-Ray Spectrometer Pre-Amp Box was re-installed on the MESSENGER spacecraft. By itself, this was one of seemingly countless small steps toward launch. However, this small step marked a major milestone for the MESSENGER mission: all seven science instruments were completely installed on the spacecraft!

In this image, the MESSENGER team can be seen installing the Pre-Amp Box, which includes electronics that amplify low-level signals from the sensor that collects gamma-ray data. Engineers had removed, tested and repaired the box last month after learning, through a NASA-wide alert system, of potential problems with two vendor-supplied diodes inside. The actual location of the device is hidden from view behind the Launch Vehicle Adapter.

The Gamma-Ray Spectrometer (GRS) will provide information that allows scientists to estimate the abundance of geologically important elements in Mercury's crust (oxygen, silicon, sulfur, iron, hydrogen, potassium, thorium, and uranium). The spatial resolution of the GRS measurements, while relatively coarse (200- to 1,000-kilometer scale), will allow scientists to investigate major questions such as: how did Mercury's crust form?

The GRS measurements will also provide key information that allows more confidence in mineralogical and compositional interpretations from instruments - such as the Mercury Atmospheric and Surface Composition Spectrometer or the Mercury Dual Imaging System - with much higher spatial resolutions (100 meters to 1 kilometer). Linkage of science data from all the spacecraft's instruments, at scales ranging from tens of meters up to a whole hemisphere, is key to MESSENGER's science strategy.

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Last updated: October 7, 2003

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