Aeolus, ESA's wind watcher


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07 November 2005

It is easy to measure wind speed and direction at one place on the ground, but what are the winds like at different heights over the entire Earth? A remarkable new European satellite, called Aeolus, will soon provide the answer.

Usually known simply as “Aeolus”, the mission is named after the god in Greek legend who was appointed “keeper of the winds”. Scheduled for launch in 2008, the spacecraft will spend three years staring down at the Earth and measuring the winds that sweep around our planet.

Aeolus with laser beam

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ESA’s wind watcher will carry one large instrument (ALADIN) that will probe all levels of the atmosphere to a height of 30 km. ALADIN consists of a powerful laser and a large telescope linked to a very sensitive receiver. The laser sends short pulses of intense light into the atmosphere. This light is scattered by molecules of gas, dust particles and water droplets.

Some of the backscattered light is collected by the spacecraft’s telescope and sent to the onboard receiver. By analysing the signal, it is possible to calculate the speed and direction of the moving air at different heights in the atmosphere.

The future is now: Lasers. Copyright: ESA.

Many measurements have to be averaged in order to achieve accurate wind observations. For every 700 laser pulses, one wind profile will be obtained. Data stored on board Aeolus will be transmitted every 90 minutes to a ground station in Svalbard, Norway. This flood of information will not only help improve weather forecasts, but also contribute to long-term climate research.

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