The Post-2000 Strategy: The ESA Earth Explorer Missions

    Christopher J. Readings
    Head, Earth Sciences Division,
    The European Space Research and Technology Centre (ESTEC),
    Noordwijk, The Netherlands


    The European Space Agency is currently in the process of defining a
    long term strategy for its Earth Observation Programme. This envisages
    two dual lines of missions, namely the Earth Explorer and Earth Watch
    Missions, the first of which would be launched in the post 2000
    time-frame i.e. beyond ERS-1/2, ENVISAT, METOP and Meteosat Second
    Generation (MSG). The Earth Explorers will basically be research or
    pre-operational missions while the Earth Watch Missions focus on long
    term operational requirements. This presentation focusses on the
    former.

    Following extensive consultations with the research community nine
    candidate Earth Explorer Missions have been identified, namely an
    Atmospheric Dynamics Mission, an Atmospheric Chemistry Mission, an
    Earth Radiation Mission, a Gravity Field and Steady State Ocean
    Circulation Mission, a Land Surface Processes and Interactions Mission,
    a Magnetometery Mission, a Precipitation Mission, a Stratospheric
    Profiling Mission and a Topographic Mission. For each of these a
    Reports for Assessment has been prepared and presented at  a
    Consultative Workshop held in May 1996 in Granada, Spain.

    During this Workshop the nine candidate Earth Explorer missions were
    presented to the Earth Observation scientific community, providing
    scientists with an opportunity to resolve queries and to comment
    generally on the nine missions prior to their peer review. Following
    this the nine missions were subject to a peer review which was carried
    out under the auspices of the Earth Science Advisory Committee (ESAC).
    Its recommendations were as follows:

         ?    All nine of the candidate Earth Explorer missions were endorsed
    as being of high scientific importance.

         ?    Four of the candidate missions were recommended for Phase A
    study, namely the Atmospheric Dynamics Mission, the  Gravity Field and
    Steady State Ocean Circulation Mission, the Land Surface Processes and
    Interactions Mission and the Earth Radiation Mission.

         ?    In addition specific recommendations made for all nine
    missions.

    The recommendations were endorsed by the Programme Board for Earth
    Observation at its meeting in September and, subject to available
    financing, plans for to implement these recommendations are in hand. In
    parallel the detailed research objectives for the Earth Explorer
    missions are being formulated.

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry