The European Space Agency’s Swarm project consists of three identical satellites launched from Plesetsk in Russia on 22 November 2013. The hope is that Swarm will provide the best picture ever of the Earth’s magnetic field and how it changes over time and if there are unexpected disturbances in it.

Swarm-satellites. (Cred: ESA/AOES Medialab)

IRF in Uppsala contributes one instrument on each of the three satellites to measure the electrical potential of the satellites, which can change quickly, especially in areas with aurora.

The instrument, a so-called Langmuir probe, neutralizes the “noise” generated by the aurora (Northern and Southern Lights) and measures the electron density, electron temperature and satellite potential of the satellite.

IRF’s Langmuir probes are part of the EFI (Electric Field Instrument) located on the front of each satellite, measuring high density plasma density, operation and acceleration to characterize the electric field around the Earth. The core of this instrument is two thermal ion imaging devices developed by a team at the University of Calgary (Canada), with the aim of being the first to show the three-dimensional distribution of the ions.

The imagers and the Langmuir probe are integrated into Swarm’s Electric Field Instrument by COM DEV in Canada.

Swarm consists of a “swarm” of three satellites. Two of them fly in parallel orbits which at the beginning of the mission are at an altitude of 460 kilometres, while the third flies in its own orbit at an altitude of just over 500 kilometres. All three satellites are identical, just under ten meters long and carry the same instruments.

More information:
Stephan Buchert, Researcher, IRF Uppsala, scb@irfu.se
Mats André, Professor, IRF Uppsala, ma@irfu.se
Jan-Erik Wahlund, Associate Professor, IRF Uppsala, jwe@irfu.se


Created by Annelie Klint Nilsson at

Last modified by Annelie Klint Nilsson at