Earth in the third dimension

The German satellite TanDEM-X was launched into orbit on a mission to map more accurately to be made available on the surface of the Earth.

The satellite will fly with radar technology with the same platform, called TerraSAR-X launched in 2007.

Both measured variations in the height of the globe with an accuracy of better than two meters.

Its digital elevation model will have several uses, from helping military aircraft to fly in ultra low height to show where rescue workers were worse the damage caused by an earthquake.

"Our goal is to generate a model to a resolution and quality as there is today," he told the BBC Dr Varka Helfritz, the company's processing of satellite images Infoterra GmbH.

"It will be a truly global product, not a patchwork of data sets that have been put together," he adds.

The Tandem-X was placed in a polar orbit a bit steeper than that occupied by the TerraSAR-X, about 514 kilometers above the planet.

"It's the first time that two satellites have been placed in a formation so close," said Brigadier General Thomas Reiter, a former astronaut and now a member of the executive board of the German Aerospace Center (DLR).

"Their orbits closer to the minimum distance of about 200 meters, which, as one imagines, will be a huge challenge for mission controllers."

Earth Changes

The pair of radar works constantly bouncing microwave pulses on the surface of the planet.

Because we keep track of how long it takes the signal to make the journey back, the instruments can measure variations in height.

The compact "ball" orbit satellites will provide a "stereo vision" allowing them to operate in interferometric mode, which acts as a satellite transmitter / receiver and the other as a second receiver.

To draw the level of detail-X TanDEM all 150 million square kilometers of Earth's land surface, will require three years.

Radar observations already have very extensive applications in military camps, civil and scientific.

Recent examples include Eyjafjallajoekull eruption in Iceland and the oil spill in the Gulf of Mexico. In the first event, the vision of microwave TerraSAR-X was able to look through the plume of ash, which allowed scientists to analyze the status of the volcano.

And on the stroke of the Gulf of Mexico, the satellite has to follow the progression of the layer of oil day and night by the way the radar signals are reflected in the contaminated water.

This is possible because the spread of oil tends to flatten the sea surface and this effect can be detected from space.

More Apps

Now, the improved data that will emerge from the mission TanDEM may extend the range of applications of radar technology.

For example, mobile operators can use the elevation model to identify the best places where they can locate their antennas.

The German Space Agency owns the hardware, services and consortium of European space projects, EADS Astrium, the company built and GbmH Infoterra has exclusive rights to market data.