Cluster II
21 Sep 2009



Cluster 2 is an ESA mission to study the Earth's magnetosphere and consists of four identical spacecraft orbiting in a tetrahedral formation.


​​​The Cluster satellites

Credit: NASA

RAL Space Involvement
Research with Adaptive Particle Imaging Detectors, Plasma Electron And Current Experiment, UK Cluster Data Centre


Main Objectives
To receive information about how the solar wind affects our planet in three dimensions.

Launch date
16 July 2000

Cluster's Joint Science Operations Centre  

The Cluster satellites orbit the Earth about three times in one week and this is the basic unit for JSOC's operational role, the so-called Planning Period. JSOC creates the overall science plan, called the Master Science Plan (MSP), covering a period of several months. The MSP is reviewed and approved by the Cluster instrument teams with feedback from ESA.

The second part of JSOC's operational role is the generation of a consolidated payload command schedule from the MSP, a process which has several steps. This is a complex event scheduling task, requiring the application of complex instrument-specific rules and constraints to the framework provided by the MSP. RAL has developed EVHA (EVent Handler and Associator), a programming language which allows the easy implementation, update and execution of complex conditional statements. EVHA allows JSOC to efficiently and robustly produce instrument-specific command schedules which are then iterated with the instrument teams.

JSOC actually works eight or more weeks ahead of command execution, which means it is dealing with several Planning Periods at any one time. RAL has developed a GUI to support and control this complex set of operational activities. The process culminates in the production of a consolidated payload command schedule, covering one Planning Period at a time, which is then delivered to ESOC(ESA's European Space Operations Centre).

The third part of JSOC's operational role is the provision of an operational website which supports the instrument science teams and ESA in planning their operations. It also links to related activities in space (for example Double Star) and on the ground (for example EISCAT).

For more information please contact: RAL Space Enquiries