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Aurora Flight Sciences. The students also worked closely with mentors at NASA Goddard Space Flight Center (the managing center for OSIRIS-REx) and spacecraft contractor Lockheed Martin. The project implemented a “function, fit, fly” philosophy for the instrument development. First a series of Engineering Test Units (ETU) were developed to test the design concepts. Many of the ETUs were developed and tested by the capstone class and included a thermal system ETU, a deployable cover ETU, and electronic boards that tested various instrument functions. The ETU period lasted through the Preliminary Design Review in January 2013 and through that academic year. Next, Engineering Models (EM) were built that tested function at a higher level of assembly and tested the fit of the instrument within mass, power, and volume constraints. There were two separate Engineering Models: a structural EM that validated the thermal system and served as a dry run for the fabrication of custom parts and mechanical integration, and an electrical EM that tested the circuit board designs and early software. EM development and test continued up to and through the Critical Design Review in February 2014. Finally, the flight hardware build began in late 2014 with the delivery of the REXIS flight CCDs from Lincoln Laboratory. Integration and test of the flight unit took place during 2015. The instrument pre-environmental review and pre-ship reviews were held in June and September 2015, respectively.

OVERCOMING THE CHALLENGES The REXIS program faced a number of challenges throughout the four years leading up to the successful integration with the spacecraft. The engineering challenges faced during the instrument development included the design of a passive thermal system that could reliably keep the CCDs below their operational temperature of -60°C, design of a one-time deployable cover to protect the CCDs from radiation during the voyage to Bennu, and the design of radiation tolerant avionics. Although REXIS is a student experiment and, as such, is risk-tolerant with respect to its own performance, the instrument needed to be suitable for integration with a much less risk-tolerant NASA spacecraft. Therefore, all spacecraft interfaces needed to be rigorously tested to ensure that

Rendezvous with Rexis

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MIT AeroAstro annual magazine 2015-2016Aeroastro 2015 16  

Annual magazine review of MIT Aeronautics and Astronautics Department research and educational initiatives.

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