From Idea to Instrument
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Design
Engineers work with a science team to convert scientific objectives into system requirements. Using computer-aided design tools, electrical engineers design the sensors and electronic subsystems that will constitute the finished instruments. Mechanical engineers design the mechanical components and packaging necessary to incorporate subsystems into a unit-level assembly. Meanwhile, research associates convert schematic designs to a physical
printed circuit board (PCB) layout using PCB-design software.
Left to right: Albert Lin, Mazaher Sivjee, Sean Nguyen.
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PCB Assembly
The assembly of PCBs is performed by technicians such as Ted Nguyen, shown here, who have been trained at the NASA school at the Jet Propulsion Laboratory. All assembly operations are performed manually, including installation of through-hole and surface-mount components, harness fabrication, and connector installation. Quality assurance inspections at this stage help to ensure that construction will meet program requirements.
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Mechanical Assembly
Electronic subassemblies and sensors are incorporated into a mechanical assembly. Eric Abendroth is shown here with a NASA sounding rocket assembly. Internal box-level harnesses have already been completed by electronics technicians. At this stage, final harnesses are added prior to system testing.
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System Testing
Functional testing at the subassembly and unit level will verify that the design meets performance requirements. Prototype and engineering models are often developed for space flight assemblies to validate a design before committing expensive flight-rated components. After the subsystems are integrated into a unit, calibrations are completed to characterize sensor performance, and embedded software is tested using sample data sets that envelop or bound the actual measurements expected. Here Yaniv Dotan tests the TWINS engineering model low-voltage power system.
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Qualification Testing
The last step prior to instrument delivery is qualification testing. Shown here Brad Johnson loads a data-processing unit and imaging proton sensor assembly in a thermal vacuum chamber. For a space flight sensor, qualification testing always includes sine and random vibration tests to verify that the instrument design will survive the launch. Thermal cycle and thermal vacuum tests are completed, and in some cases acoustic and pyro-shock tests may also be performed. Engineers may also conduct electromagnetic compatibility testing and magnetic cleanliness surveys as required by the parent spacecraft mission.
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