Swarm (spacecraft)

Swarm (English for Swarm ) is the name of a satellite mission of ESA. The launch took place on 22 November 2013. The mission is part of the Earth Explorer mission program.

There are three identical satellites will work together with a mass of 500 kg each. They orbit the earth relatively close to the earth in the ionosphere, on polar orbits at altitudes of 450-550 km. Together they are the strength, orientation and temporal variation of the geomagnetic field measured. From the results of predictions about the long-term development of the magnetic field to be derived. All three satellites were transported together by a rocket into space. The project will thus continue the successful CHAMP project.

The satellites were built by a German -British team of EADS Astrium in Friedrichshafen. The components supply companies in Europe, for example, builds RUAG Space the GPS receiver.

The cost of the construction of the satellites are about 86 million euros, the total cost of the mission about 200 million euros.

Scientific payload

The satellites each carry seven instruments for the implementation of the project, these are:

• The Vector Field Magnetometer ( VFM ), the main scientific instrument of the SWARM mission. It is measured with higher accuracy than previous missions like Ørsted, CHAMP and SAC -C was possible, the vector components of the geomagnetic field;
• The Absolute Scalar Magnetometer (ASC ), this is primarily used for calibration of VFM;
• The Electric Field instrument (EFI), equipped with sensors for the measurement of ion incident angle and speed;
• The accelerometer (ACC), for determining the acceleration of the satellite, which is not caused by gravity, such as air resistance, and the solar wind;
• The Laser Range Reflector ( LRR), this reflected laser beams from a measuring station on the earth's surface and allows accurate distance measurement;
• The star tracker system ( STR ), this provides highly accurate position data of the satellites and
• The GNSS receiver ( GPSR ), this provides independent real-time information on the location and time of the satellite.

Data Products

The Swarm mission will provide the following data products for the magnetic field, the electric field and the ionosphere as well as for the orbit and air drag (air resistance). A distinction is made between Level -1b and Level 2 products. Level -1b data are the calibrated time series of individual satellites, while Level -2 data products from the Level 1b data derived, in part using the combined satellite measurements ( constellation ).

• Level 1b: magnetic field strength
• Magnetic field vector

• Comprehensive inversion ( modeling of all magnetic field components )
• Nuclear magnetic field
• Crustal magnetic field
• Electrical conductivity of the mantle

• Level 1b: electric field vector (EFI)
• Plasma density
• Plasma temperature
• Ion drift velocity ( vector)

• Magnetospheric field ( ring current )
• Ionosphärenfeld (SQ)
• Radial and field-parallel currents ( FAC)
• Plasma Bubble Index ( IBI)
• Total Electron Content ( TEC )
• Electric field at the equator (EDF )

• Level 1b: Air - drag- vector ( ACC)
• Position, time stamp (Medium Orbit Determination - MOD)

• Euler angles
• Calibration of the accelerometer
• Precise orbit determination (Precise Orbit Determination - POD)
• Air density and winds in the thermosphere

Project office in Germany

The Swarm project office is located at the German Research Centre for Geosciences, GFZ, in Potsdam in cooperation with the DLR. It is preparing to launch satellites to evaluate the mission before - as well as the use of the Swarm results in various geosciences. The coordinator of the German project office is Lühr Hermann, one of the pioneers of the Swarm mission. The specific aim is the best ever survey of the geomagnetic field in order to increase our knowledge about the processes in the Earth's interior and in the near-Earth space.