Farnborough, U.K. — On 27th June, the ESA Industrial Policy
Committee unanimously approved the Aeolus mission with Astrium
as the proposed contractor for the initial programme. The
Aeolus spacecraft, with a mass of about 1 tonne and an expected
lifetime of 3 years, is scheduled for launch in October 2007.

Aeolus, named after the mortal appointed by the Greek gods to be
keeper of winds, is ESA’s second Earth Explorer Core mission.
Aeolus will carry only one instrument, the Atmospheric Laser
Doppler Lidar Instrument (ALADIN), which will provide global
observations of wind with a vertical resolution that will satisfy
the requirements of the World Meteorological Association in both
climate research and operational weather forecasting. At present,
accurate global wind profiles are not available and are therefore
a major deficiency in the Global Observing System.

Aeolus will be placed in a Sun-synchronous orbit at an altitude
of 400 km, enabling it to collect information from anywhere on
the planet. The Aladin lidar (laser detection and radar)
instrument will create a wind profile showing the relative
strength and direction of winds at different altitudes.

Astrium has already been awarded the pre-development contract
for ALADIN. Development of the instrument will continue and the
integrated pre-development model is scheduled for delivery in
the Autumn of 2003.

ALADIN will be the first spaceborne wind lidar offering global
coverage. Measurements are taken every 0.1 second and then
averaged over 7-second periods (during which time the satellite
will have travelled 50km) to obtain wind profiles for altitudes
from 0 to 30 kilometers.

The ALADIN instrument is based on the Direct Detection Doppler
Wind Lidar concept, which operates in the near UV band (355
nanometres) and uses a telescope for both emission and
reception. It is an active instrument which fires laser pulses
towards the atmosphere and measures the Doppler shift of the
return signal, backscattered at different levels in the
atmosphere. It combines a fringe-imaging receiver (analyzing
aerosol and cloud backscatter) and a double-edge receiver
(analyzing molecular backscatter) in a single instrument. The
two scattering mechanisms have different spectral properties
and wavelength dependencies.

The Aeolus core team is led by Astrium Ltd as prime contractor
and includes Astrium SAS with prime responsibility for the
ALADIN instrument. Astrium GmBh is responsible for the platform
electrical architecture and subsystems while SAAB Ericson Space
AB supplies the spacecraft computer.

ASTRIUM is a joint venture owned 75% by EADS, European
Aeronautic Defence and Space Company and 25% by BAE SYSTEMS.
In 2001 Astrium had a turnover of 1.9 billion Euros with
8,400 employees in France, Germany, United Kingdom and Spain.
Astrium is currently refocusing on its satellite business
activities covering civil and military telecommunications and
Earth observation, science and navigation programmes, avionics
and equipments.