The technical term for rotating a satellite in space on its own axis is ‘attitude control’. There are several approaches to this and Bremen’s ZARM Technik AG has become a ‘hidden champion’ in the industry with its attitude control system.
The 146-metre high ‘Fallturm’ drop tower in Bremen’s Technology Park rises up into the sky like a giant white needle. Over the past 30 years it has become a symbol of Bremen’s aspirations as an emerging science hub. At the base of the slender tower is a two-storey building. This is the home of ZARM – the Center of Applied Space Technology and Microgravity. Or rather, this is where three organisations are based under the roof of ZARM. These are the University of Bremen’s Institute of Science, the ZARM Fallturm operating company, which makes the drop tower available for research in zero gravity conditions, and ZARM Technik AG, which is actually not that closely linked to the drop tower, but is all about space technology.
Since 1997, ZARM Technik AG has become a specialist for satellite attitude control in low Earth orbit. “In Europe, we are part of practically every tender. And even in Japan and the US, some of the biggest aerospace companies like the NASA Jet Propulsion Laboratory and Northrop Grumman are customers of ours,” says Holger Oelze, CEO of ZARM Technik AG.
Satellite attitude control in low Earth orbit
But what exactly is it that these specialists in Bremen are doing so well? They have perfected the magnetic torquer, a device used to rotate satellites on their own axis. The magnetic torquer does not have any movable parts – it is essentially just an electromagnet.
In zero gravity, a magnet automatically aligns with the Earth’s magnetic field like the needle of a compass and the magnetic torquer uses this principle for its purposes. ZARM’s specialists skilfully control the electromagnet in a satellite to align it with the Earth’s magnetic field, essentially using the magnetic field as an anchor for rotation manoeuvres.
A rotation can take up to several minutes. The torque generated by the magnetic torquer is very low, but in the vacuum and zero gravity of space, it is enough to move several tonnes of equipment.