The space community is showing a growing interest for shifting from designs based on fully-custom components to a more cost- and time-effective approach based on commercial off the shelf components. As a result, there is a growing need for methods to develop quickly reliable on-board electronic systems that meet reliability constraints typical of space-oriented applications. The purpose of this paper is to present an approach for developing Linux-based on-board computers for data handling serving as building blocks for low-cost scientific satellites. The approach is based on a scalable technique that mixes hardware and software error detection techniques to balance implementation cost with dependability.