The Swarm menu to your right provide information concerning the SPPA activities for this mission.
Please refer to Swarm Mission page for a complete overview of what is Swarm.
A brief description of the mission, its operations and main mission highlights is available in the sections below:
Mission and Sensors Description
The primary objective of the Swarm mission is to provide the best survey of the geomagnetic field with multi-point measurements enabling the examination of the magnetic field's temporal evolution to gain new insights into the Earth system, improving the understanding of the planet's interior and climate. The Swarm mission consists of three spacecraft that orbit the Earth in slightly different polar orbits – two fly in a 450-Kilometer orbit and the third in a 530-Kilometer orbit with a different inclination. Each of the spacecraft carries five instruments: a Vector Field Magnetometer, an Absolute Scalar Magnetometer, an Electric Field Instrument, Accelerometers and a Laser Range Reflector.
Absolute Scalar Magnetometer (ASM)
The Absolute Scalar Magnetometer (ASM) measures the magnetic field intensity at the tip of the boom. The ASM is an absolute instrument, i.e. it is not subject to changes of its intrinsic parameters over time. It uses the PPS as the absolute, external reference.
Vector Field Magnetometer (VFM)
The Vector Field Magnetometer (VFM) measures the magnetic field vector at the tip of the optical bench on the boom. The sensor is a 3-axis Compact Spherical Coil (CSC) with a 3-axis Compact Detector Coil (CDC) inside. The instrument operates as a closed-loop system adjusting the compensating CSC currents to maintain a null field at the detector coils within the sphere. The currents in the CSC coils are measured and digitized (by an ADC) and this constitutes the raw measurements of the instrument.
The Star Tracker (STR) is comprised of three Camera Head Units (CHUs) mounted on the innermost end of the optical bench. Nominally, the attitudes of all three heads are provided simultaneously at 1 Hz rate, however one head is regularly blinded by the Sun leaving the attitudes of just two heads. The attitudes of the 2-3 CHU are combined into one attitude, the attitude of the STR Common Reference Frame (CRF). The combination uses the method described in [RD3]. The attitudes of CRF are then interpolated to obtain the CRF and S/C attitudes at required time instants: 50 Hz VFM measurements, 2 Hz EFI measurements and UTC seconds.
Electric Field Instruments
The Electric Field Instrument determines the ion density, the ion drift velocity, and the electric field at the S/C front panel (in-flight). The instrument consists of two components: the Langmuir Probe (LP) and the Thermal Ion Imager (TII).
Through the GPS antenna, the GPS receiver (GPSR) receives the signals from all of the antenna visible GPS satellites. The L1b processing corrects for known effects related to the Swarm instruments and satellite. The external errors e.g. due to the GPS segment are corrected in the orbit determination processing.
Its main objective is to precisely measure non-gravitational perturbing accelerations with temporal and spatial variability. Factors that cause non-gravitational accelerations are air drag, winds, Earth albedo (reflected solar radiation and thermal radiation) and direct solar radiation pressure. The instrument data can provide air density measurements that can be used with magnetometer data to provide new insights into geomagnetic processes.