"Around Venus by Balloon"
described in these pages was submitted to the European Space
Agency in December
2010. Despite favourable scientific and technical
the proposal was not selected at this time. The rationale for the
mission remains as compelling as ever, and the EVE team remains
committed to the need for an in situ Venus mission. Therefore we are
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.
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