A set of key questions have been identified that formulate gaps in our current knowledge of Venus:
The answers to these questions, together with the comprehensive studies under the different themes described below, will lead to an improved understanding of perhaps the most fundamental question of all: Why has Venus evolved so differently compared to the Earth, in spite of the similarities in terms of size, basic composition and distance to the Sun?
The scientific objectives of the Venus Express mission have been concisely expressed within seven scientific themes. The aim is to carry out a comprehensive study of the atmosphere of Venus and to study the planet's plasma environment and its interaction with the solar wind in some detail. Dedicated surface studies are also performed. The seven scientific themes are:
The first three themes are divided into sub-themes that refer to the upper, middle and lower parts of the atmosphere. The corresponding approximate limits for these regions are, above 110 km, between 110 and 60 km, and below 60 km. The scientific requirements within the sub-themes are broken down into units that can be directly addressed by individual measurements by the Venus Express scientific instruments.