The central computer also communicates with the central computer of the PLM via the same bus.įigure 2: The Envisat Service Module being readied for shock testing in the ESTEC facilities (image credit: ESA) It controls the SM equipment via a standard onboard data-handling bus. The propulsion module on top of the cone contains four tanks, which hold over 300 kg of hydrazine.Ī single central computer containing both command and control and AOCS functions performs on-board data management. Once deployed, the array is rotated to point continuously towards the sun using a solar-array drive mechanism, which is attached to the base of the central cone.
The SM includes eight batteries, and the solar array. A box-shaped metallic structure, with aluminum honeycomb panels, supports the electronic equipment and surrounds the central cone.
The SM is built around a CFRP (Carbon Fiber Reinforced Plastic) cone as the primary structure, with a launcher interface at one end and the propulsion module at the other. The PPF has been developed and integrated by EADS Astrium Ltd. Service Module: The SM is derived from the SPOT Mk-II bus design. The PPF itself comprises: 10) 11) 12)ġ) The service module ( SM) providing the standard satellite support functionsĢ) The payload module ( PLM), providing accommodation and supporting subsystems (data handling, power, communications) to the payload complement. The development of the payload instruments for Envisat started after the split of POEM-1 into Envisat and MetOp at the Ministerial ESA council meeting in December 1993.įigure 1: Artist's rendition of the deployed EnviSat spacecraft (image credit: ESA)Ĭonfiguration: The EnviSat satellite comprises the PPF bus and the payload complement. This allows the EnviSat mission to focus on environmental issues that are more research-oriented with a package of essentially preoperational instruments. The key element of the split scenario is the transfer of the meteorological instrument package onto a separate platform with a morning orbit devoted primarily to operational meteorology and climate monitoring. The updated POEM program of 1992/93 considers a split scenario of two dedicated missions called EnviSat (Environmental Satellite) and MetOp (Meteorology Operational Programme). This scenario was followed in 1991 by the POEM-1 mission (a single satellite mission) which fulfilled both environmental and meteorological mission objectives. The objectives of the M-series were dedicated studies in meteorology/atmosphere/ocean/ice/environment, while the N-Series was considered for the study of land resources/atmosphere/environment.
The first series was planned with a Morning Orbit (M), the second series with an (After) Noon Orbit (N). 5) 6) 7) 8) 9)īackground: Originally, two parallel and staggered mission series were proposed in the POEM program. The EnviSat program of ESA is a renamed successor program to the original POEM (Polar Orbit Earth-Observation Missions) utilizing the Polar Platform (PPF). Major disciplines covered: meteorology, climatology, environment, atmospheric chemistry, vegetation, hydrology, land use, ocean and ice processes. Contribution to the understanding of the structure and dynamics of the Earth's crust and interior. Continuation and improvement of the services provided to the worldwide operational meteorological community. Monitoring and management of the Earth's resources, both renewable and nonrenewable. The overall objectives are: studying and monitoring the Earth's environment on various scales, from local through regional to global. EnviSat is an Earth observation mission of ESA (European Space Agency).