Design
The two STEREO observatories are nearly identical with selective redundancy. Each spacecraft bus was built by the Johns Hopkins University Applied Physics Laboratory (APL), in Laurel, Md., and NASA Goddard Space Flight Center procured the instruments. Each observatory and its instruments were integrated at APL.
The STEREO mission consists of two solar-powered, 3-axis-stabilized spacecraft, each with a launch mass — including propellant — of approximately 1,412 pounds (642 kilograms). The spacecraft is communicating with the APL-based Mission Operations Center via NASA's Deep Space Network.
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Artist's concept of the twin STEREO observatories studying the sun.
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The significant challenge in spacecraft design is the large number and extent of the instrument fields-of-view, coupled with the various instruments' competing design requirements to ensure successful science observations.
The major design drivers to support the science instrument performance
are a conductive outer surface for the energetic particle experiments, stringent electromagnetic compatibility and interference requirements for the radio burst tracker, and contamination control of both volatiles and particulates for the imager experiment.
The spacecraft bus consists of six operational subsystems supporting two instruments and two instrument suites. This combination provides a total of 16 instruments per observatory. The subsystems include: command and data handling; radio frequency communications; guidance and control; propulsion; power; and thermal.
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