ALIS a multi-eyed voyeur in a plasma universe

The Northern Lights are a visible result of physical processes in inner space. By studying the optical signal from the Northern Lights and similar phenomena, we can gain new knowledge about the physics behind them. In the long run such pure research may be of great importance for applications in our future supply of energy and for future space travel.

A dissertation at Umeå University, Sweden, by researcher Urban Brändström at The Swedish Institute of Space Physics, focuses on the construction and operation of a new land-based metering system, ALIS, designed for optic studies of the Northern Lights and other weak light phenomena. ALIS now consists of six unmanned metering stations placed in a net of squares of about 50 km on a side. Each station is equipped with a light-sensitive CCD camera and a filter wheel with narrow-band filters. It is therefore possible to carry out studies of the different “colors” in the phenomenon observed. Since the stations’ fields of vision overlap, it is also possible to glean information about altitude.

ALIS performed the first unequivocal observations of artificial light emissions at high latitudes. They were generated by a powerful radio transmitter at the EISCAT facility in Tromsø, and they were observed simultaneously by several ALIS stations. This made it possible to obtain altitude profiles for the first time. Experiments of this type thus offer exciting potential for enhanced understanding of the physics of inner space.

Recently ALIS performed observations of a meteor trail in which a preliminary study offers certain evidence that water has been observed in the meteor. ALIS has also been used for studies of Polar Stratospheric Clouds, which are seen as having a close connection to the deterioration of the ozone layer.