4 Final Report - Emits - ESA

4 Final
Report
for the reception of payload telemetry and (2) the mission is focused on frequent revisit for systematic
observations and real time instantaneous access emergency management.
4.6.2.1 Command and Control
Geo-Oculus will allow permanent contact with the Mission Control System. One main advantage is
that commanding the satellite is possible at any time, without having to wait for a ground station
contact. On the other hand, the Mission Control System will receive a permanent flow of
Housekeeping telemetry, during day and night. Hence, a reasonable schedule for operating the
spacecraft should be established in order to minimise the operations cost.
4.6.2.2 Flight Dynamics
As a baseline for the Geo-Oculus orbit determination the spread spectrum ranging method using a S-
Band repeaters and S-Band Ground Stations has been selected. The stations will have to include the
necessary ranging equipment, and the Flight Dynamics System will have to process the ranging
information from the stations in order to perform high accurate orbit restitution.
4.6.2.3 Mission Planning
Efficiency of mission planning operations is essential to gain the full benefit of the satellite agility. As
far as the routine (or background) mission is concerned, the baseline observation schedule can be
established well in advance and loaded on-board the satellite at given times. However, actual
meteorological conditions must also be taken into account in order to minimise the likelihood of cloudy
scenes and thus useless observations.
For the emergency monitoring mission(s), reactivity is at stake. This means that, as soon as a catastrophic
event requiring fast scheduling of an observation occurs, it shall be possible to superimpose
an emergency observation to the nominal plan. As for the routine missions, the emergency observations
shall also take into account the meteorological conditions during the mission planning stage.
From a mission planning point of view, simple conflicts management rules can be implemented, which
allow for giving priority to emergency observations over routine ones in an automatic manner.
Additional conflict management strategies are needed to dissolve possible resource conflicts between
different emergency monitoring missions, which may coexist within the same period of time. For
handling these situations it will be useful to dynamically assign priority levels to the different
emergency events.
Strategy baselines on the implementation of emergency observation requests into the schedule have
already been given in [RD 3], including scenarios for combining routine and emergency observations.
The straight forward approach to avoid congestion is to allocate only a given percentage of
observation capabilities to routine observations, so that in total, enough resources will be available to
include both routine and emergency observations.
As can be seen from the above considerations, one major issue in the context of the on-demand
scheduling of emergency observations is staffing, unless the whole process could be automated. If not
the case, personnel will need to be available both on PDGS and FOS side to take into account and
schedule unforeseen requests. For solving this issue, an intermediate approach like for Sentinel-3 Fire
Monitoring mission can be adopted, i.e. working during normal working hours only (8/24 5/7) outside
periods of natural disasters, and working round the clock during periods when such events are the
most likely to occur (e.g. April to October for the fire season in Southern Europe).
Doc. No: GOC-ASG-RP-002 Page 4-81
Issue: 2
Date: 13.05.2009 Astrium GmbH