[Northern lights (with Table
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The aurora is not only beautiful to look at, there is also a lot of research going on. The scientists are among other things trying to find out why there are auroras, how often there are strong auroras and so on. I will try to explain how some of the research is done.
The particles that make auroras possible don't reach the ground, they are stopped by the Earth's atmosphere. This makes it difficult to study those particles. If you want to study the behaviour of the particles you have to send instruments to make measurements in the higher atmosphere.
The instruments sent into space with a rocket or satellite are called payload.
Sounding rockets are used for accurate measurements of selected auroras. They can reach heights of approximately 1000 kilometres and make measurements for about 10 minutes. A lot of sounding rockets for aurora research have been launched from Esrange 40 kilometres east of Kiruna.
The picture shows how a sounding rocket is launched to make measurements in space.
More about rockets
If you want to reach areas far away from the Earth or measure for a longer period of time you use satellites. Due to such projects being very expensive and demanding it is common that many countries cooperate when it comes to satellites. The advantage of cooperation is that each country does not need as much money and or as many people working on the satellite.
How is a satellite project carried out?
Some Swedish satellites
In space, data from the different instruments are translated into radio signals that are transmitted to a receiver on Earth, where they are recorded on magnetic tapes. In most cases the ground station can only reach the satellite during a period of its orbit, therefore the data is often stored in memory banks on the satellite until the next contact with Earth.
The picture shows why the ground-based station only can reach the satellite during a period of its orbit.
If everything goes well now the most interesting part of the project starts for the scientists, to analyse the data. It is often possible for more than one explanation to correspond to the data. If you for example measure a lot of electrons for a short moment you don't know if the satellite flew through an area of electrons or if it was a very short electron burst.
Measurements from the ground are also very important. Ground measurements have some advantages compared to measurements in space: all the measurements can be performed at the same location (the rocket or satellite is constantly moving), and it is possible to repair the instruments if they break down.
More about ground measurements