This work got its start by trying to answer the question "how do you evaluate the scientific performance of the ESA's Science Programme missions?" For many years, the decision makers responsible for the content of the ESA Science Programme have been provided with information for each mission including, but not limited to, the number of publications published, the number of publications that are highly cited, the total number of citations used, various statistical metrics and the number of unique author names. However, this reporting only provides snapshots of these missions and was not widely distributed. In this book, we report on a systematic study of these metrics and their evolution with time to provide insights into mission successes and the communities exploiting the data provided by the Science Programme’s missions. In addition, we examine the outcomes of the announcements of observing opportunities for ESA’s observatory missions, INTEGRAL, Herschel and XMM-Newton to provide insights into the evolutions of the user communities with time, location and gender. Finally, we examine the provision of payload elements for ESA’s Science Programme missions. We use the number of payload investigators to give insights into the levels of contribution and exploitation of the different ESA Member States. This book is open access under a CC BY license.