=> Update : ESA is progressing fast. All lands overflown by Sentinel-2B were available in PEPS on November 12th, thanks to EDRS relay satellites.The Sentinel-2 mission, made of two twin satellites S2A and S2B, has been stated "operational" since beginning of October, even if each satellite was only observing on one orbit out of two everywhere except in Europe and Africa. As a result, the 5 days revisit was only available in these two continents.  But in the new Sentinel-2 mission status report, ESA announced this very good piece of news :

Sentinel-2A and -2B are together acquiring Europe, Africa and Greenland with 5 days revisit. The rest of the World is revisited every 10 days jointly by the two satellites. Full systematic 5-day revisit everywhere will be reached once EDRS downlink becomes available operationally, assumed during December 2017 for both S2A and S2B.

The "EDRS downlink" uses a laser terminal on board S2A and S2B, that sends data to a

the EDRS-A spacecraft in GEO transmitting high-rate data on laser beam technology between LEO spacecraft and Earth (image credit: ESA)
geostationary satellite of the European Data Relay Satellites constellations (EDRS), which is then retransmitted to a ground station. I let you imagine the pointing accuracy necessary to point a laser to a satellite at 36000 km distance. This is achieved thanks to a system provided by the German aerospace agency DLR. (For memory, such a transmission was done at CNES  for the first time on SPOT4 using the PASTEL-SILEX communication system, but it was only for a successful demonstration and was not used operationally). S2B should start first, and the ramp up phase has started ! S2A communication system had an anomaly (not detailed by ESA), which seems to have been overcome lately. A great thanks to ESA and DLR for allowing us to get these long awaited data. It will be a very nice Christmas present for all users outside Africa and Europe, who  will benefit from a doubled likelihood to get cloud free observations. Our  MAJA L2A processor for  cloud detection and atmospheric correction, which uses multi-temporal information will also benefit from this increased repetitivity. MAJA L2A products are available from Theia land data center. 

Laisser un commentaire

Votre adresse e-mail ne sera pas publiée. Les champs obligatoires sont indiqués avec *

Ce site utilise Akismet pour réduire les indésirables. En savoir plus sur comment les données de vos commentaires sont utilisées.