Improving satellite communications through space forecasting

Space might be silent, but it is not the serene place many imagine, especially in the upper levels of the Earth's atmosphere.

Radio waves, including those used by satellite systems, can be distorted by the ionosphere, which is a part of the Earth's upper atmosphere.

These effects can cause errors in satellite data communications and positioning errors in satellite navigation systems such as GPS and Galileo.

''The ionosphere is a region of the upper atmosphere that is partially composed of ionised gases that are called plasma,'' says Professor Matthew Angling, new Research Chair in Space Environment and Radio Engineering of Defence Science and Technology Laboratory, at the University of Birmingham.

''Below a certain frequency, radio waves launched from the Earth, can be reflected by the ionosphere and return to the ground; it is this effect that allowed inter-continental transmissions like the first radio telegraph.

The appointment is part of  Defence Science and Technology Laboratory and the Royal Academy of Engineering's efforts to help make these satellite systems and other terrestrial radio systems more reliable.

Professor Angling is working to develop more accurate models of the ionosphere in order to better predict its effects on radio waves.

''At higher frequencies, radio signals can pass through the ionosphere from space to the ground or vice versa. In either case, the free electrons in the plasma affect the propagation of the radio wave and can introduce signal delay and distortion.''

The ionosphere, which extends approximately from an altitude of 90km to 1,600km, is highly dynamic. The ionisation is largely produced by solar radiation, but its detailed structure is also influenced by the Earth's magnetic field and by the solar wind.

Under normal solar conditions, the ionosphere can vary enough to cause significant problems to high precision applications such as surveying and off-shore drilling. However, under extreme conditions, the ionospheric disturbance may be great enough to cause problems to commercial satnav systems.

Professor Angling will create more reliable, physics-based, data assimilation ionospheric models that will allow ionospheric forecasts to be made over hundreds of square kilometres and over longer periods of time.

He says, ''Being able to accurately forecast the behaviour of the ionosphere even three to six hours ahead will be a significant improvement in current capability. It would give operators of affected systems enough time to quantify the disruption and to adjust their systems to minimise the effects.''

To collect measurements for his forecasting and modelling work, Professor Angling is also developing new instrumentation - a new type of small, low cost satellite to be launched in a cubesat.