German radar satellites fly tight space waltz

Jonathan Amos - Two German radar satellites are now flying in tight formation as they prepare to make the most detailed ever 3D map of the Earth's entire surface.

TanDEM-X and TerraSAR-X have moved to within 350m of each other as they sweep around the planet at 7km/s.

The pair will soon begin an intense observation campaign that will pin down the variation in height across the globe to an accuracy of better than two metres.

This digital elevation model (DEM) will be put to myriad uses - everything from improving the safety of aircraft navigation to understanding better which areas of ground are most at risk during a flood.

TerraSAR-X was launched in 2007. TanDEM-X was put in space in June, since when it has been brought closer and closer to its more established sibling.

The very close proximity manoeuvres were conducted step-by-step over the course of the past week.

"It's tricky and I must confess we've all been a bit nervous," Manfred Zink, from the German space agency (DLR), told BBC News.

Continue reading the main story

“Start Quote

All the people doing science around the Earth, be it geology, hydrology, whatever - for them, topography of the terrain is a key input”

End Quote Dr Manfred Zink Project manager for the TanDEM-X ground segment

The orbits flown by the satellites are ever so slightly offset, which means they trace paths across the sky that look like the strands of a double helix. This should ensure they never bump into each other.

via BBC News - German radar satellites fly tight space waltz.