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Instrument for fast measurement of the solar wind

Czech instrument for russian satellite Spektr-R

Project duration: ongoing since 2005

Project manager: Prof. Jana Šafránková

The BMSW instrument was designed and built at the Faculty of Mathemathics and Physics at Charles University in Prague by professor Němeček, professor Šafránková and assistant professor Přech, as a part of the plasma complex for the Russian astrophysical satellite Spektr-R (Radioastron). The satellite was successfully launched from Baikonur on 18th July 2011 into the elliptic orbit, which is suitable for measurements of processes in the solar wind. Every 8.5 days, the Spektr-R spacecraft approaches Earth to 10 000 km, while the farthest point from the Earth reaches 390 000 km, roughly the distance of the Moon.

While electric and magnetic fields in space are commonly measured in the order of kHz or MHz, the technical obstacles limited the measurements of solar wind parameters to several seconds, fractions of Hz. For determining the parameters of the solar wind, it is necessary to find out, how many particles are moving in a given direction and their velocity. It is important to speed up the measurement, because around 1 Hz the processes involved in dissipation of the solar wind energy change completely. Although it is possible to describe the slower processes by a magneto-hydrodynamic modeling, faster processes require a full kinetic description of moving particles.

The method used by a BMSW device is based on a simultaneous measurement of solar wind ion flux by six Faraday cups fixed to solar panels of the spacecraft, hence oriented approximately but permanently in the solar wind direction. Three of the detectors, which are diverted from the Sun – Earth line, determine the direction in which particles move. The other three detectors measure their density and temperature. The parameters are determined by two methods. In the first case, the instrument measures with frequency of 2 Hz the full ion distribution. Assuming that this distribution is Maxwellian, it is possible to speed up the measurement time down to 32 ms, which is about hundred times faster than provides any other instrument currently in orbit.

Department of Surface and Plasma Science, Faculty of Mathematics and Physics Charles University in Prague

The scientific research group of space physics is oriented  to experimental investigations of the space environment, the Sun-Earth relationships and predictions of space weather conditions. Members of the group participate in a development of space plasma instruments, processing and interpretation of data collected during many international projects and are involved in a laboratory research as well. Design and development of scientific instruments for international projects is predominantly focused on studies of plasma parameters, charged particles and wave processes, development of diagnostic methods and sensors for these studies. Laboratory simulations of processes in the solar wind and Earth’s magnetosphere are extended to investigations of the Moon and Mercury environment.

What would you name as main benefits?

“With high time resolution data, we are able to perform the space plasma research in conditions known as plasma kinetic scale. Such conditions have not been achieved by any previous spacecraft and they were known only theoretically. The unprecedented resolution enables us to determine the structure of interplanetary shocks, the Sun influence of our planet, eg. puts under risk the terrestrial powerline networks or satellites in orbit.”