UCL Department of Space and Climate Physics


Broadband Energisation and Auroral Development Satellites (BEADS)

Joint Scientific Space Mission Chinese Academy of Science (CAS) – European Space Agency (ESA)


6 August 2018

The Broadband Energisation and Auroral Development Satellites (BEADS) mission will comprise a wellinstrumented two spacecraft mission designed to provide science closure on two key physics questions in space plasma physics, to: discover the plasma instability responsible for the detonation of the magnetospheric substorm and its magnetospheric driver and, quantify the loss of radiation belt electron precipitation into the upper atmosphere. The mission is low-cost, low-risk, uses an easily accessible orbit and involves a simple operational concept. The specific and compelling science goals targeted by BEADS cannot be addressed by any other current or planned space mission.

Primary Science Goal

BEADS will discover the key physical processes behind explosive energy release in the near-Earth space environment, which characterise magnetospheric substorm onset. To address this, BEADS will use a unique combination of multi-satellite auroral imaging and broad energy range electron measurements to unravel the spatial and temporal behaviour of this explosive energy release mechanism. Determining the partitioning of energy between electromagnetic waves and precipitating auroral particles is of critical importance in substorm onset to distinguish between competing substorm onset models. BEADS is designed specifically to study these relationships in detail for the first time. The BEADS primary science objective builds upon recent discoveries from the NASA THEMIS mission of the discovery of repeatable auroral fluctuations along the substorm onset arc. These oscillations signal the action of a plasma instability operating in near-Earth space at the start of the substorm, but the nature of the plasma instability remains poorly understood. Over the past thirty years, single point measurements have advanced our understanding of the plasma physics responsible for driving the aurora. However, in order to distinguish spatial and temporal effects, essential during dynamic times such as substorm onset, multi-point measurements are absolutely vital. BEADS will provide the first two-point diagnosis of magnetotail instability, its dynamical evolution, and the dominant auroral acceleration mechanisms from a combination of auroral displays, magnetic field behaviour, and the variation of electron fluxes with energy. On average, BEADS will sample the first critical minute of ~90 substorm onsets.