Martin Endemann

ALADIN airborne demonstrator: a Doppler Wind Lidar to prepare ESA´s ADM-Aeolus Explorer Mission

The Atmospheric Dynamics/Aeolus mission is the 4th Earth Explorer mission of the Earth Observation Explorer Programme of the European Space Agency (ESA). Its objective is to measure vertical tropospheric profiles of horizontal wind speed components. These global observations of wind profiles from space will improve the quality of weather forecasts and advance our understanding of atmospheric dynamics and climate processes. The 1.3-ton, 1.4-kW Aeolus spacecraft uses an incoherent Doppler Wind lidar (ALADIN) to measure wind speed. It uses a tripled-frequency Nd:YAG laser emitting ultraviolet pulses at a repetition rate of 100 Hz, during a measurement period of 7 sec repeated every 28 sec. The return signal is detected with a double interferometric receiver composed of a Fizeau interferometer to detect the Mie signal scattered by aerosols and a double-edge Fabry-Perot interferometer to detect the Rayleigh signal scattered by atmospheric molecules. A custom-made accumulation CCD is used to detect and integrate the return photons over several laser pulses. The spacecraft has recently passed the CDR level and launch is planned for 2008. An airborne version of the ALADIN instrument has been made with equipment developed during the pre-development phase of the mission. An interferometric receiver with a high-level of representativity to the space receiver and a laser transmitter breadboard have been refurbished and complemented with a telescope, a co-alignment mechanism and custom control and processing electronics to produce the first airborne, direct-detection Doppler Wind lidar worldwide. The lidar was functionally tested in flight in October 2005 and will be used in ground and airborne campaigns in 2006 and 2007 to prepare the exploitation of the Aeolus space mission.

Atmospheric dynamics mission: Aeolus

The Atmospheric Dynamics Mission (ADM-Aeolus) represents the second Earth Explorer core mission within ESAs Living Planet Programme. Following launch in 2007 the spacecraft would be injected into a sun-synchronous, polar orbit and provide global observations of atmospheric wind profiles throughout the troposphere and the lower part of the stratosphere. Due to its excellent sampling capabilities, combined with a systematic processing and dissemination of key data products in near-real-time (i.e., within 3 hours after sensing) Aeolus would enable major advances in operational short- and medium-range weather forecast systems. The ALADIN payload on board Aeolus is a direct detection Doppler Lidar system, equipped with a pulse laser operating in the ultraviolet) and a dual-channel receiver system. The spectrometer assembly would allow independent recording of the Mie (aerosol) and Rayleigh (molecular) components of the atmospheric backscatter signal, covering an overall height range from ground up to approximately 25 km. The Aeolus mission concept foresees systematic processing and dissemination of various data products over the envisaged mission lifetime of three years. This includes both the generation and delivery of Level 1B data (calibrated Doppler wind observations) to meteorological service centers in near-real-time and the off-line distribution of higher level products, serving a variety of scientific applications

Michelson Interferometer for Passive Atmospheric Sounding (MIPAS): design overview and current development status

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a high-resolution Fourier-Transform spectrometer which is being developed as one of the ESA payload instruments to be flown on-board the Envisat environmental satellite. MIPAS will be used to measure concentration profiles of atmospheric constituents on a global scale over a period of several years. The first MIPAS instrument model will undergo integration and test during early 1997, prior to which the individual subsystems will be fully tested and characterized. This paper summarizes the critical instrument and subsystem requirements and gives an overview of the MIPAS design to meet those requirements.

Michelson interferometer for passive atmospheric sounding for ENVISAT-1

MIPAS, the Michelson Interferometer for Passive Atmospheric Sounding, is a high-resolution Fourier-Transform spectrometer designed to measure concentration profiles of atmospheric constituents on a global scale. It will observe the atmospheric emissions from the Earth horizon (limb) throughout the mid infrared region (685 - 2410 cm-1, 14.6 - 4.15 micrometers ), which will allow the simultaneous measurement of more than 20 atmospheric trace gases, including the complete NOy-family and several CFCs. MIPAS will provide global data coverage, including in particular the polar regions, where the stratospheric chemistry is currently exhibiting alarming changes.

The ADM-Aeolus mission

The Atmospheric Dynamics Mission ADM-Aeolus will make direct measurements of global wind-fields. The aim is to provide global observations of wind profiles with a vertical resolution that will satisfy the requirements of the World Meteorological Organization. The only payload is the Atmospheric Laser Doppler Instrument (ALADIN), a direct detection Doppler lidar operating in the UV. It will determine the wind velocity component normal to the satellite velocity vector. These wind profile measurements will be assimilated into numerical forecasting models to improve the quality of the global three-dimensional wind fields. To make full use of the data, the global wind profile data must be made available to the weather prediction centers in near real time. EADS-Astrium (UK and France) and their subcontractors develop Aeolus and ALADIN. Most subsystems have been completed, and the assembly of the Flight Model is well under way, and proceeding to a launch envisaged in late 2008. Details of ALADIN and several of its subsystems are reported in various papers of this conference.

Manufacturing of an airborne demonstrator of ALADIN: the direct detection Doppler wind lidar for ADM-Aeolus

Due for launch in 2008, the Atmospheric Dynamics Mission (ADM-Aeolus) has been selected as ESAs second Earth Explorer Core Missions within its Living Planet Programme. Its payload aims at providing measurements of atmospheric wind profiles with global coverage. The key element of ADM-Aeolus is the Atmospheric LAser Doppler Lidar INstrument (ALADIN), a Direct Detection Doppler Lidar in the ultra-violet spectral region operating on aerosol and molecular backscatter signals in parallel. The ALADIN instrument belongs to a completely new class of active optical earth-observation payloads with limited power requirements and high reliability over a three-year lifetime. It will be the first European Lidar in space. Technological challenges have been addressed in an early stage by a pre-development programme that consisted of designing, manufacturing and testing a functional representative model of the receiver of ALADIN (the Pre-Development Model, PDM), and a breadboard of the transmitter. The pre-development programme has been successfully completed and both receivers and transmitter are being refurbished in an airborne configuration. The ALADIN airborne instrument demonstrator (A2D) will be used for ground and airborne campaigns prior to the launch of the satellite. This paper presents the main characteristics of the airborne instrument and the goals of the campaigns.

The ENVISAT Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)

MIPAS, the Michelson Interferometer for Passive Atmospherice Sounding, is a high-resolution Fourier-transform spectrometer designed to measure concentration profiles of atmospheric constituents on a global scale. It will observe the atmospheric emissions from the Earth horizon (limb) throughout the mid infrared region (685-2410 cm/sup -1/, 14.6-4.15 /spl mu/m), which will allow the simultaneous measurement of more than 20 atmospheric trace gases, including the complete NOy-family and several CFCs. MIPAS will provide global data coverage, including in particular the polar regions, where the stratospheric chemistry is currently exhibiting alarming changes.

ATLID: the first preoperational ATmospheric LIDar for the European polar platform

Results of a study dealing with the conceptual design of a spaceborne atmospheric lidar instrument (ATLID) are presented. ATLID is designed to operate on the Polar Platform, a future earth-observation satellite. ATLID yields data on the height, strength, and depolarization properties of scattering layers (i.e., clouds, planetary boundary layer) in the lower atmosphere.

ALADIN: the first european lidar in space

The Atmospheric LAser Doppler INstrument (ALADIN) is the payload of the ESA’s ADMAEOLUS mission, which aims at measuring wind profiles as required by the climatology and meteorology users. ALADIN belongs to a new class of Earth Observation payloads and will be the first European Lidar in space. The instrument comprises a diode-pumped high energy Nd:YAG laser and a direct detection receiver operating on aerosol and molecular backscatter signals in parallel. In addition to the Proto- Flight Model (PFM)., two instrument models are developed: a Pre-development Model (PDM) and an Opto-Structure-Thermal Model (OSTM). The flight instrument design and the industrial team has been finalised and the major equipment are now under development. This paper describes the instrument design and performance as well as the development and verification approach. The main results obtained during the PDM programme are also reported. The ALADIN instrument is developed under prime contractorship from EADS Astrium SAS with a consortium of thirty European companies.

ALADIN TxA — A spaceborne UV laser

ALADIN TxA is the Transmitter-laser Assembly for the Aeolus wind lidar satellite. It is a frequency tripled, single mode Nd:YAG laser with 50 Hz PRF and a three year lifetime. The design and the development program are presented.