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TOPEX/Poseidon: Perspectives on an Ocean Planet

- Nadir Side of the Spacecraft

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nadir

The nadir, or bottom side of the spacecraft, always faces the earth. TOPEX/Poseidon operates in this orientation to keep the altimeter antenna, microwave radiometer, and Earth Sensor Assembly Module pointed toward the center of the earth. From this view you can also see the Signal Conditioning and Control Unit on the MMS.