Many space-related impact studies have been carried out in the past, but there is no conclusive, comprehensive evaluation of the economic and social effects of public investments in space. Such evaluations are not easy to perform, for several reasons: the space sector is not a recognised category in official statistics; social benefits, which are likely to be very important, are hard to assess; and impacts from R&D are complex and occur in the long term. However, important steps can be made towards better evaluation of impacts. The full set of impacts of space investments may be simultaneously evaluated from both a 'bottom-up' and a 'top-down' perspective. In the bottom-up perspective, each effect is measured separately, while the top-down perspective provides a framework for integrating the effects. Although both perspectives have their own advantages and drawbacks, combining them yields both detailed and integrated results. Our discussion of the bottom up approach starts by identifying an extensive list of impacts. Next, data availability issues and methodological improvements are identified, leading to recommendations on programmes to collect data and perform case studies. Finally, suggestions are made for presenting impacts in the form of a scoreboard. The core of the top-down evaluation methodology proposed is social cost benefit analysis. Effects are weighted, where possible, on the basis of observed market prices or other estimations of monetary values. For effects that are hard to measure or monetize, multi-criteria analysis can be applied using surveys and expert opinion. Our core recommendations are to clearly define the space sector, to collect additional data, and to use improved methodologies. Social, strategic and environmental impacts deserve special attention, aiming at a more comprehensive coverage of impacts. Comprehensive evaluations can contribute to more upport for space expenditures.