Miniature devices shed light on satellite interference

The Northern Lights occur when electrically charged solar winds collide with plasma clouds at altitudes of 80–500km. Turbulent conditions found within plasma clouds during the Northern Lights can reflect or completely block radio signals being sent to and from satellites.

Tore André Bekkeng, the Oslo University research fellow responsible for developing the electronics and producing the algorithms, told The Engineer: ‘The instrumentation we have developed uses four miniaturised cylindrical probes to measure electron density within plasma clouds.’

The device — dubbed ‘m-NLP’ — measures electron density at a rate of 7kHz so that scientists can get a closer look at what is happening within the plasma cloud.

‘It is an improvement on previous instrumentation, because it gives the absolute electron density at 1m spatial resolution, compared with… the kilometre scale,’ said Bekkeng. ‘By having measurements of absolute electron density down to metre scale, we can for the first time see the smallest thinkable structures in the ionosphere, which is the height region where the Northern Lights occur.

‘The reason why we want to investigate these structures is that if you have a structure that is half the size of the wavelength of the radio signal you are transmitting, you will experience backscattering and scintillation of the received signal,’ said Bekkeng. ‘For GPS this will result in reduced accuracy, and during solar storms the users can experience no GPS lock in high-latitude areas. It also affects radio communication in polar areas, which can affect trans-polar flights.’

The 2003 Halloween Storms were so severe that air-traffic controllers had to re-route aircraft flying over the poles. ‘The aircraft authorities had to divert all flights that were above 65°N further south because they couldn’t get radio communication with the planes,’ said Bekkeng.

The new device that has been developed through Oslo University’s STAR project will be attached to 20 of 50 CubeSat satellites that Bekkeng said are set to be launched in 2014 from Russia as part of the QB50 space project.

The miniature satellites are 10 x 10 x 10cm and weigh 1kg each so that they can be launched on one rocket into a polar orbit 320km above the Earth.

The satellites will lose speed during their orbit due to air resistance and will continuously degrade over their three- to-eight-week service period, before eventually falling into the atmosphere and combusting.

NASA plans to use the new instrumentation in a rocket launch in Alaska.