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Envisat gives the Earth a check-up

17 Jun 2002

Dramatic high-resolution pictures give detailed information about changes in the Earth's climate and environment.

Envisat, the largest and most sophisticated Earth observation satellite ever built, has beamed back its first dramatic pictures of the Earth.

Launched only a month ago by the European Space Agency, Envisat uses a medium-resolution imaging spectrometer (MERIS) to assess environmental and climate change by monitoring the atmosphere, oceans, land and ice.

Its first pictures reveal a huge phytoplankton patch produced by the 'upwelling' mechanism along the coast of West Africa. Changes in climate affect the intensity of the upwelling with important consequences for marine ecosystems, fisheries and the local economy.

Envisat was also launched just in time to witness the break-up of the Larsen B ice shelf in Antarctica. The collapse of the 3250 km2 ice shelf is the latest dramatic event in a region of Antarctica that has experienced unprecedented warming in the last 50 years.

MERIS is an imaging spectrometer that measures the solar radiation reflected by the Earth, at a ground spatial resolution of 300 m, in 15 visible and near infrared spectral bands that are programmable in width and position. It can image the whole globe in just three days.

Envisat weighs 8000 kg and is as big as a bus. It is orbiting in an Earth polar orbit at 800 km altitude and is an automatic space observatory with ten highly sophisticated instruments observing the Earth.

These include: a laser retroreflector to support-to-satellite ranging and altitude calibration; a Michelson interferometer for passive atmospheric sounding; and a scanning imaging absorption spectrometer for atmospheric chartography.

Further information and high-resolution Envisat images are available on the ESA web portal at http://www.esa.int/envisat.

Project information is available on the dedicated Envisat website http://envisat.esa.int.

Nadya Anscombe is editor of Optics.org and Opto & Laser Europe magazine.

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