GSC Sentinel-2 PDGS OCD - Emits - ESA

GSC Sentinel-2 PDGS OCD
Issue 1 Revision 2 (draft) - 25.07.2010
GMES-GSEG-EOPG-TN-09-0008
page 92 of 350
In summary, the global downlink capacity offered by a well distributed CGS network to
recover the data on-ground is the major driver impacting Sentinel-2 data timeliness.
As illustrated on Figure 4-8, it was simulated that, starting from the 4-stations CGS network
baselined in [AD-03], the global data availability with NRT-compatible timeliness can be
achieved by adding two complementary stations.
Figure 4-8 Simulated global NRT-compatible data-age on-ground using a CGS network
composed of Kiruna, Svalbard, Maslapomas, Prince-Albert, Matera and Gatineau stations
4.3.10.2 Real-Time Data Timeliness
Based on the mission requirements, the spacecraft design includes the capability to downlink
the payload data in real-time as soon as it is acquired by the instrument. Although primarily
aimed at serving regional data to ground-stations operated outside of the GSC framework,
such capability could be used over a limited number of core stations to achieve data
availability in real-time.
Considering that the nominal data supply rate of the MSI (490Mbps) is comparable to the
downlink rate (520Mbps), transmitting data in real-time would not represent a large overhead
on the overall downlink budget if used seldomly.
For instance, it could be considered that by operating one CGS located over Europe for
acquiring Sentinel-2 direct downlinks during descending passes, real-time data timeliness
could be achieved regionally over Europe. As another benefit, this would allow any LGS
placed under the CGS mask to receive in parallel the Sentinel-2 direct downlinks performed
over that station. Figure 4-9 depicts (in yellow) the complete coverage of all European
countries achievable using one CGS.
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