It’s difficult to keep track of the unique and interesting innovations that pop up in our world day after day. Much is made about the pull of gravity, but what would it feel like to have a situation where objects are totally ‘weightless’ on the earth’s surface, just floating mid-air?
Special electromagnetic components called magnetic torquer rods are being used by the South African National Space Agency (SANSA) to orient satellites in low-earth orbit, with the help of Gaetan Laurent, a student of Aerospace Engineering at the French Air Force Academy, who had recently interned with the Agency.
In respect of this project, Laurent worked with Danie Gouws (SANSA’s Applied Science and Technology Manager), and Abdullah Sardiwalla (SANSA Electronics Technician).
A magnetic torquer rod (also known as torquer rod or torquers) is a long ferromagnetic rod with many windings of electroconductive wire wrapped around a coil. As electrical current flows through the wire, the coil induces a magnetic field which interacts with Earth’s own magnetic field called the geomagnetic field. The two fields can act together to control the rotation of satellites in different directions in space. Magnetic torquer rods are commonly used as attitude control system(ACS) actuators for micro satellites, small satellites and geostationary satellites.
In his speech, Gouws stated, “Because they depend on Earth’s magnetic field to generate torque, magnetic torquer rods are limited to use in satellites with an altitude lower than 2000km”.
According to the Agency, Laurent placed a strong, rare earth magnet inside a small model of a satellite, and the satellite model below a strong electromagnet. Using a magnetic sensor that could detect how far away the satellite model was from the electromagnet, he could switch the electromagnet on and off at a very high rate, depending on the distance of the model satellite from the electromagnet. This was borne out of SANSA’s need to conduct an experiment to demonstrate the concept of weightlessness.
In the course of the experiment, an electric circuit was designed to supply power to the electromagnet. This was to enable the magnetic sensor to detect any satellite models that were coming close to it and ultimately switch off the electromagnet.
“An external magnetic torquer rod, when activated, interacts with the small magnet on the model satellite to stabilise a spinning levitated satellite, and demonstrate the ability of a torque rod to change the orientation of the model satellite”, Gouws added, further elaborating on Laurent’s experiment.
It is unclear where this ongoing project would ultimately lead to, but ambition is one of the first few steps on the road to innovation, and in trying to replicate the weightlessness in space on earth, SANSA is showing how ambitious it really is.