After ERS-1 and ERS-2, Envisat-1 is ESA's next Earth-observation spacecraft, launch of which is currently planned for July 1999. There will be ten instruments on board providing a wide range of measurements in such areas as atmospheric chemistry, ocean/ice studies and solid Earth.
Steady progress is being made on the development of the payload instruments and the Polar Platform for the Envisat-1 mission. The Polar Platform structural model recently arrived at ESTEC, where it is undergoing a complete mechanical qualification and verification programme in the various test facilities. This impressive spacecraft is 10 m high, 2.3 m wide and weighs around 8 tons. The structural model uses a carbon-fibre-reinforced- plastic structure built by CASA (Spain) and panels provided by NFT (Norway). It has been assembled by the Polar Platform Prime Contractor MMS-B in Bristol (UK).
The structural model is currently undergoing modal survey testing, which will be followed by deployment shock tests and acoustic tests. In October, it will be installed on ESTEC's newly-developed Hydra (hydraulic vibration) test facility for vibration testing. The Hydra has been built specifically for testing large satellites compatible with the Ariane-5 launcher.
For these tests, the flight-representative structure will be equipped with mass dummies of electronics boxes and mechanical models of several instruments, in particular the ASAR (Advanced Synthetic-Aperture Radar) antenna. The test programme is planned to be completed by the end of the year.
In parallel with this activity, the proto-flight model of the Polar Platform Service Module is under final assembly in MMS-T in Toulouse (France), while the engineering model of the complex payload equipment bay is in final acceptance testing in Dornier (Germany).
ESA EOQ 52