Payload Processing Electronics (PPE) for the International Space Station (ISS) was the focus of a key project by ALTEN Technology. This initiative successfully designed and delivered flight units for deployment on the ISS. Employing an efficient Agile development process, ALTEN Technology rapidly advanced from initial concept to the delivery of both a lab unit for client use and a robust flight unit. The scope of work included developing and testing a PPE backplane and mechanical enclosure, integrating it with third-party VPX cards, and creating essential verification software. Ultimately, a fully tested PPE flight unit, designed for up to a year of operation on the ISS, was delivered, complete with traceable system requirements meeting stringent Mission Class D standards.