EVE - European Venus Explorer

An in-situ mission proposal to Venus within the

ESA Cosmic Vision 2015-2025 programme for the second call in 2010

"Around Venus by Balloon"

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Last update: 16.11.2011

EVE 2010 mission proposal paper just published

The proposal described in these pages was submitted to the European Space Agency in December 2010. Despite favourable scientific and technical reviews, the proposal was not selected at this time. The rationale for the EVE mission remains as compelling as ever, and the EVE team remains committed to the need for an in situ Venus mission. Therefore we are pursuing future possibilities in collaboration with international partners, and preparing for future European mission opportunities.

Venus is the twin sister of the Earth, with similar size and inventories of carbon dioxide and nitrogen. However, it has evolved quite differently and now has a massive carbon dioxide atmosphere and a thick layer of sulfuric acid clouds, generating a massive greenhouse effect which heats the surface up to  about 450°C. The complex radiative, dynamical and chemical processes in the lower atmosphere and in the cloud layer, which are crucial to determining the current greenhouse warming and circulation, are still poorly understood. Also poorly known are current exchanges of atmospheric constituents with the surface and interior of the planet and at the interface with space, both of which are important for determining climate evolution.. It is thought that the atmosphere of Venus could be more primitive than the Earth’s atmosphere, and therefore be representative of our early atmosphere.

An in situ mission to Venus is urgently needed, for two main purposes. Firstly, detailed measurements of noble gas abundances and isotopic ratios are needed to understand the evolution of Venus, providing an essential reference for the study of evolution of Earth and the terrestrial planets. Secondly, in situ measurements of radiative, dynamical and chemical processes in the cloud layer of Venus are needed in order to understand its greenhouse effect and circulation, which determine the climate of Venus today. Understanding why an ocean of water developed on Earth, but not on Venus, or why the tectonic regime of Venus is so different of Earth’s one, definitely requires an in-situ mission to Venus. Such a mission will also be of crucial importance to prepare the interpretation of future observations of Earth-type exoplanets.

The general objective of the EVE mission, following the European Venus-Express mission, is to understand the evolution of Venus and its climate, with relevance to terrestrial planets everywhere. It was proposed for the first time to the European Space Agency in 2007, as an M-class mission under the Cosmic Vision Program. Although it was not chosen for programmatic reasons, it was “seen by the SSWG as an attractive mission which was highly ranked scientifically”.
When proposed in 2007, the EVE mission consisted of one balloon platform floating at an altitude of 50-60 km, one descent probe provided by Russia, and an orbiter with a polar orbit which would relay data from the balloon and descent probe and perform science observations. EVE will be re-proposed to ESA in 2010, in a slightly different cooperation scheme, but keeping the balloon as the central element of the mission.
This website, aimed at both EVE science team members and the broader public interested by the mission, provides access to documents and any useful information relevant to the development of the project: key phases, meetings, cooperation scheme and schedule of the proposal preparation.