Data Driven Ground Station Usage Optimisation on the ESA Gaia Mission (or how to get more with less)

摘要

The use of the ESA Deep Space Ground Stations for the Gaia Satellite (scheduled for launch in 2012) can be optimised through mission analysis; the on-station time required to downlink data collected during an observing period is a function of the volume of science data to be downlinked (limited by onboard Mass Memory size, and driven by the area of the sky being observed) and the telemetry rate used during the pass. The volume of science data is deterministic given an initial point in the (known) galactic scanning law and a representative galaxy model. Gaia uses a novel Phased Array Antenna; six different telemetry rates are selectable up to 8.718 Mbps. The maximum viable telemetry rate can be determined from the spacecraft distance, the Phased Array Antenna and the Ground Station Antenna gain variations as a function of elevation. With this information the time required from the Deep Space Ground Stations can be efficiently planned in advance according to actual need rather than a simple fixed schedule. Using this data driven scheduling it is then possible to optimize the usage of the Ground Station time available to the mission to achieve higher data recovery rates.