Cluster: A Challenging Mission To Plan

Ian M. Palmer, Mario Merri, Colin. R. Haddow
mmerri@esoc.esa.de
ESA / ESOC

Abstract:
The Cluster mission is aimed at a study of small scale structures that
are believed to be fundamental in determining the behavior of key 
interaction processes of cosmic plasma. The mission will be controlled
from the European Space Operations Centre (ESOC). ESOC is also in charge
of the commanding of the eleven scientific payloads on-board the four
Cluster spacecraft after negotiation with the Cluster Principal
Investigators (PI). To coordinate and consolidate the requests for
scientific observations of the Cluster scientific community, the
Joint Science Operation Centre (JSOC) has been established in the UK.
The process of planning the Cluster operations involves several
iterations between ESOC and JSOC.

The Cluster Mission Planning System (CMPS) is an off-line system that
allows the ESOC mission operations staff to plan in advance the
Cluster operations. Initially, the CMPS supports the ESOC operations
stuff in the process of negotiations with JSOC. This allows potentially
conflicting inputs from the PIs and the necessary spacecraft operations
to be identified and corrected. After the resolution of all planning
conflicts, the CMPS can schedule on-board and on-ground operations
with the aim of maximising the scientific mission return. This has to
be done within the constraints imposed by Cluster orbits (e.g. eclipses,
distance from the Earth), the on-board system (e.g. data storage, power
availability) and the on-ground system (e.g. ground station visibility,
availability). The final output of the CMPS is the generation of
maschine and man readable schedules to command the four spacecrafts
and the two ESA ground stations.

The Clauster challenge to mission planning is the coordination of
simultaneous operations an four spacecrafts and on three ground
stations (two ESA and one NASA-DSN for the WBD experiment). This
raises special problems that have been successfully addressed by the
CMPS and described in this paper.