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About Envisat

Envisat logo

Envisat was ESA's successor to ERS. Launched on 1 March 2002 on an Ariane-5 rocket from Europe's spaceport in French Guiana, Envisat was the largest Earth observation spacecraft ever built with 10 instruments aboard and at eight tonnes was the largest civilian Earth observation mission ever launched.

More advanced imaging radar, radar altimeter and temperature-measuring radiometer instruments extended ERS data sets. This was supplemented by new instruments including a medium-resolution spectrometer sensitive to both land features and ocean colour. Envisat also carried two atmospheric sensors monitoring trace gases.

The Envisat mission ended on 8 April 2012, following the unexpected loss of contact with the satellite.

Envisat Objectives

The main objective of the Envisat programme was to endow Europe with an enhanced capability for remote sensing observation of Earth from space, with the aim of further increasing the capacity of participating states to take part in the studying and monitoring of the Earth and its environment.

The primary objectives of Envisat were:

  • to provide for continuity of the observations started with the ERS satellites, including those obtained from radar-based observations
  • to enhance the ERS mission, notably the ocean and ice mission
  • to extend the range of parameters observed to meet the need of increasing knowledge of the factors determining the environment
  • to make a significant contribution to environmental studies, notably in the area of atmospheric chemistry and ocean studies (including marine biology)

These were coupled with two linked secondary objectives

  • to allow more effective monitoring and management of the Earth's resources
  • to better understand solid Earth processes

The mission intended to continue and improve upon measurements initiated by ERS-1 and ERS-2, and to take into account the requirements related to the global study and monitoring of the environment.

Envisat Instruments

The Advanced Along-Track Scanning Radiometer (AATSR) provided continuity of the ATSR-1 and ATSR-2 data sets of precise Sea Surface Temperature.

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The Advanced Synthetic Aperture Radar (ASAR) was a C-band instrument that provided continuity with the image mode (SAR) and the wave mode of the ERS-1/2 AMI.
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The Global Ozone Monitoring by Occultation of Stars (GOMOS) measured atmospheric constituents by spectral analysis of defined spectral bands.

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The Medium Resolution Imaging Spectrometer (MERIS) was a programmable, medium-spectral resolution, imaging spectrometer operating in the solar reflective spectral range.

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The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) was a Fourier transform spectrometer for the measurement of high-resolution gaseous emission spectra at the Earth's limb.

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The Microwave Radiometer (MWR) measured the integrated atmospheric water vapour column and cloud liquid water content, surface emissivity and soil moisture over land, surface energy budget investigations to support atmospheric studies, and ice characterization.
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The Radar Altimeter 2 (RA-2) determined the two-way delay of the radar echo from the Earth's surface to a very high precision: less than a nanosecond. It also measured the power and the shape of the reflected radar pulse.

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The Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) was an imaging spectrometer whose primary mission objective was to perform global measurements of trace gases in the troposphere and in the stratosphere.
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What is the non-scientific instrument payload?

The Laser Retro Reflector (LRR) was a passive device used as a reflector by ground-based SLR stations using high-power pulsed lasers.

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The Doppler Orbitography and Radio-positioning Integrated by Satellite (DORIS) was a microwave tracking system utilised to determine the precise location of the Envisat satellite.
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