Environmental satellite ENVISAT successful

Valuable data on the Earth's atmosphere for over five years

The European environmental satellite ENVISAT has collected data on the state of the Earth system for five years. © ESA
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The environmental satellite ENVISAT celebrates its anniversary: ​​for five years it has been orbiting the earth at a height of 800 kilometers, gathering information about the state of oceans, landmasses, glaciers and the atmosphere. So far, ENVISAT has sent around 500 terabytes of data to earth, providing the basis for more than 1, 300 research projects.

In its first five years, the environmental satellite ENVISAT, operated by the European Space Agency (ESA), has collected a volume of data roughly equivalent to a tower of DVDs at the height of the Cologne Cathedral. The data is processed into over 50 different information products. Of the ten scientific instruments on board, two even come from Germany: the interferometer MIPAS (Michelson Interferometer for Passive Atmospheric Spounding) and the atmospheric sensor SCIAMACHY (Scanning Imaging Spectrometer for Atmospheric Chartography).

"Atmosphere Spy" in action

For example, SCIAMACHY compares direct sunlight with sunlight weakened by the atmosphere. Because the gases contained in the air leave characteristic "fingerprints" in the spectrum. This allows researchers to draw accurate conclusions about the concentration of air pollutants. In addition to nitrogen dioxide, SCIAMACHY was able to measure more than a dozen other trace gases in the Earth's atmosphere globally. This allowed German scientists to create the world's first maps of the greenhouse gases carbon dioxide and methane.

Recently, a German-American team of scientists found that SCIAMACHY data in some areas of the US showed a reduction in nitrogen dioxide emissions by up to 35 percent compared to 1999 levels. The reason for the decrease in nitrogen dioxide concentration is the newly installed exhaust gas control systems at three large power plants. The scientists' investigation shows how successful measures can be to clean power plant exhaust gases. In areas of the US, where the air is polluted with nitrogen oxides, especially by road, the researchers, however, could not find any improvements.

Rainforests emit methane

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Another surprise was data from SCIAMACHY, which showed an unusually high concentration of methane over the tropical rainforests. All current model calculations had predicted significantly lower values. Methane together with carbon dioxide is one of the most important greenhouse gases. So far, scientists have assumed that the rainforests have a purely positive effect on the share of greenhouse gases, as they store carbon dioxide. The reason for the high methane concentration could only be a hitherto unknown biological process in which the gas was produced by rainforest plants. Scientists from the Max Planck Institute for Nuclear Physics in Heidelberg discovered the unknown process in laboratory measurements.

The future is also taken care of

There are already six other scientific satellites in the ESA "Living Planet" program. Some instrument concepts of ENVISAT are also to be realized within the framework of the GMES (Global Monitoring for Environment and Security) program. GMES is a joint initiative of the European Commission and the European Space Agency ESA for Global Monitoring for Environment and Security.

(DLR, 03.04.2007 - AHE)