Absolute Scalar Magnetometer (ASM) Vector Field Magnetometer (VFM) Star Tracker (STR) Electric Field Instrument (EFI) GPS Receiver (GPSR) Accelerometer (ACC).

All the three Swarm satellite are equipped with a set of six instruments:

• Absolute Scalar Magnetometer (ASM)
• Vector Field Magnetometer (VFM)
• Star Tracker (STR)
• Electric Field Instrument (EFI)
• GPS Receiver (GPSR)
• Accelerometer (ACC)

At the tip of 4 meter boom  a scalar helium magnetometer for highly accurate field strength determination is located. The Optical bench consists of three star cameras and  vector magnetometer.  The star cameras measure the orientation of the satellite up to one thousand^th of a degree. For gravitational field measurements, a three-axis accelerometer is mounted in the center of gravity of the satellite. This position ensures that the measuring device is not disturbed by the orbit dynamics, but only measures the forces acting on the spacecraft, e.g. Air resistance and light pressure. The measurement of air density and wind also makes the accelerometer possible. The ionosphere is investigated by the electric field instrument. The ion dispenser is its core and will measure the direction and velocity of the incoming ions. Of these sizes, the ion drift, the surrounding electric field, the ion type and temperature can be derived. Two additional Langmuir probes measure the electron density and temperature. A GPS receiver allows precise orbit determination. A laser retroreflector is used on the underside to check the position data. With its help, the distance from the ground can be measured very precisely. The magnetometer load of the 3-axis stabilized spacecraft is directed backwards during flight. The slim shape of the satellite with a small cross-section in the direction of flight allows a long mission time in a low flight altitude.

Detailed information on the Swarm instrument availability

• Instrument unavailability