Body text
Satellite constellations to study the magnetosphere
The Earth's magnetosphere is the region of space dominated by the Earth’s magnetic field. It is a highly dynamic environment where plasma energisation and transport processes occur across multiple time and spatial scales.
Plasma particles gain energy through shocks, magnetic reconnection, turbulence, and waves, but the exact mechanisms remain unclear. These processes involve multiscale coupling from the large fluid scales to the small electron scales, which makes them difficult to unravel. Yet, understanding plasma energisation in the Earth’s magnetosphere is key to improve space weather predictions, but also to advance our knowledge of other astrophysical objects.
The Earth’s magnetosphere acts as a natural laboratory where man made satellites study processes at play in other (as yet inaccessible) astrophysical environments.
Previous multi-spacecraft missions had a limited ability to study the coupling between different plasma scales. The four Cluster spacecraft enabled observations at a single spatial scale, while THEMIS provided timing information but was limited to the large fluid-scale dynamics of the magnetosphere.
Resolving multiple scales at the same time requires larger constellations. The Plasma Observatory mission aims to bridge this gap by enabling simultaneous measurements with a constellation of seven spacecraft:
- one mother-craft carrying an advanced suite of instruments and
- six daughter-craft performing complementary measurements with simpler instruments.
The role of BIRA-IASB
Among the mother-craft payload, the four IMS ion detectors aim at measuring ions at a high time resolution. These detectors use high voltages to select the ion energy and arrival direction. IMS requires a fine-tuned control of the high voltages and of the measurement timing sequence, which is the role of the control unit (CU) for which BIRA-IASB is responsible.
The CU is at the interface between the detector and the spacecraft. It is in charge of collecting the measurement and housekeeping data, of transmitting commands to the detector head, of the thermal control of the instrument.
At this stage, the team at BIRA-IASB defines the CU design to optimize IMS performance, while fitting in the constraints of a space borne instrument: a limited mass and energy consumption but a high reliability level.
Plasma Observatory is among the three missions that have been selected for further study out of the initial 27 proposals. The three selected candidates should come up with a complete design in mid-2026. Then, only one mission will be selected for implementation.
