Thursday, November 23, 2006, 16:00
WHGA Auditorium
H. Svedhem, ESA/ESTEC
Abstract:
Venus, our closest planetary neighbour in space has, in spite of being visited
by several US and Soviet missions in the early era of space exploration, still
a large number of unsolved mysteries to be answered. Rotating clockwise, at a
very low rate but with hurricane forces winds and spectacular atmospheric
double vortices at the poles, with surface pressure and temperatures far above
that of the earth, we find the planet in many respects at the extreme end of
the terrestrial planets. This is quite surprising since Venus and Earth likely
were formed almost as twins, being similar in size, mass and basic composition
and located in the same region in the solar system. The evolution of the two
planets has however taken dramatically different directions. The early
missions have provided a basic understanding of the physical conditions but
the time has now come to carry out a more detailed investigation of our sister
planet.
The Venus Express mission was launched from Baikonur, Kazakhstan, on 9
November 2005. After a 5 months cruise phase, on the 11th of April 2006, the
spacecraft was inserted into a highly elliptical polar orbit. After another
two months of testing and commissioning activities the nominal operational
phase started 4 June. The main mission objective is to carry out a
comprehensive study of the atmosphere and the plasma environment and to study
a number of questions related to the surface of Venus. All studies will be
carried out both at a global level and at a detailed regional level. The
nominal duration of the mission is two Venus sidereal days (486 earth days)
with a possibility for extending the mission for a period of at least another
two Venus days. The orbit is optimised for remote observations at a global
scale from high altitude, and for detailed studies of the northern hemisphere
from low altitude, both at varying solar aspect angles. It will also allow for
in-situ plasma measurements covering a large range of distances from the
planet. The payload is selected for studies of the physics and chemistry of
the atmosphere and the clouds and the related circulation at unprecedented
accuracy and coverage. The interaction of the upper atmosphere with the solar
wind will be investigated by dedicated instruments. By adapting the existing
Mars Express design to the Venus environment and reusing most subsystems the
spacecraft was built in just above three years. This is by far the fastest ESA
science mission ever built. The scientific instruments are based on selected
instruments designed for Mars Express and Rosetta with two completely new
instruments added. The spacecraft and the payload are performing very well and
the instruments are producing data of astonishing quality.
This talk will summarise the scientific questions about Venus and describe the
mission and the first results.