Abstract. We describe the design and deployment of the middleware for the Collaborative Information Portal (CIP), a mission critical J2EE application developed for NASA's 2003 Mars Exploration Rover mission. CIP enabled mission personnel to access data and images sent back from Mars, staff and event schedules, broadcast messages and clocks displaying various Earth and Mars time zones. We developed the CIP middleware in less than two years time using cutting-edge technologies, including EJBs, servlets, JDBC, JNDI and JMS. The middleware was designed and implemented as a collection of independent, hot-deployable web services, providing secure access to back end file systems and databases. This service-oriented approach to developing an integrated system is an example of cutting edge middleware design. Throughout the middleware we enabled crosscutting capabilities such as runtime service configuration, security, logging and remote monitoring. This paper presents our approach to mitigating the challenges we faced, concluding with a short review of the lessons we learned from this project and noting some of the things we would do differently and why.