Changing world politics and military emphasis have brought considerable pressure on space agency financial budgets and a shift to increasing commercialisation of space activities. Budgetary pressure, coupled with the rapid advancement of commercial and consumer micro-electronics, has catalysed the use of smaller and more computationally capable satellites as a ‘faster, cheaper, better’ means of realising space missions - complementary to conventional large satellite systems. Affordable small satellites, however, require a very different approach compared with established space engineering techniques.