A major anomaly on the Sentinel-1B satellite occurred in the early morning (UTC) of 23 December 2021, causing it to stop generating data. Teams of specialists immediately investigated and took action to bring the satellite back to life.
Solving the Sentinel-1B anomaly
Specific actions were taken over several days to implement an onboard configuration change that would prevent the re-occurrence of the anomaly, that could result in satellite safety risks. These actions included simulations and system validation activities on the ground, before upload to the satellite.
During the initial investigation it was announced that the satellite unavailability period would potentially last up to 2 weeks.
On 7 January 2022, the resuming of the operations was carefully prepared including the on-board configuration changes preventing the anomaly to occur again.
However, during the preparation of the recovery operations, it became clear that the initial anomaly was a consequence of a potential serious problem related to a unit of the power system of the Sentinel-1B satellite. The operations performed over the last days did not allow to reactivate so far a power supply function required for the radar operations.
Further investigations to identify and remedy the root cause will be performed over the next days.
Strong efforts have been and are still being deployed by the ESA and industry teams to analyse the issue and try to reactivate the satellite operations. Apart from a specific issue related to a power subsystem unit, the satellite is under control, the thermal control is properly working and the regular orbit control manoeuvres are routinely performed. Updated information will be published on the Sentinel Online news.
Sentinel-1A monitors natural hazards
The Copernicus Sentinel-1 observation scenario supports the systematic coverage of Copernicus Services areas of interest, of European land and coastal waters, of global tectonic/volcanic areas, as well as of other areas worldwide for various applications. The observation plan also includes a regular mapping of all land areas worldwide.
To ensure the continuation of important missions, like monitoring natural hazards, specific actions were performed to make available Sentinel-1A imagery (from regular observations part of the baseline plan) in the frame of the call 854 from the International Charter Space and Major Disasters on 7 January 2022. This call is related to volcanic eruption in the Galapagos Islands.
Additionally, Sentinel-1A observations are planned over ocean and coastal waters to support the monitoring of the tropical cyclone Tiffany (South Pacific Ocean, near Australia). The Sentinel-1A spacecraft is in a stable state, operating in Nominal Mission Mode (NMM). The Flight Operations Segment (FOS) ensuring the monitoring, control and commanding of the satellites is operating nominally. Orbit control manoeuvres are performed once a week.
Even though Sentinel-1A is now the only of the two Sentinel radar observation mission that remains operational, it also experienced a minor anomaly. A mission update notification on 26 December 2021 said: “Copernicus Sentinel-1A was unavailable between 24/12/2021 19:32 UTC and 25/12/2021 12:08 UTC, due to an onboard software anomaly. No SAR data were acquired during this period. Data acquisitions taking place indicatively within 2 hours before this period may have been affected.”
It seems that this issue was just a minor hiccup, that was quickly resolved.
Sentinel-1 data and its users
By 6 January 2022, a total of 563,773 users have self-registered on the Sentinels Open Access data Hub; 37,7 million Sentinel-1 product download have been made by users, representing 46 PB of data. 7.45 million Sentinel-1 products are available on-line for download, representing 12 PB of data.
Sentinel-1C and 1D
When launched in 2014 and 2016 the Sentinel-1 Synthetic Aperture Radar (SAR) satellites had an expected lifespan of about 7 years. Sentinel-1A is almost at that expected mission duration, but Sentinel-1B has only been operational for just over 5 years.
The successors to these two SAR satellites are in the process of being built.
Sentinel-1C is the third of the Sentinel-1 radar satellite series and will ensure data continuity for the many services offered by the EU’s Copernicus programme. The Sentinel-1C satellite, equipped with a C-band radar, will provide radar images of the entire Earth’s surface as part of the Copernicus programme funded by the European Union and the European Space Agency (ESA). Thales Alenia Space is prime contractor for Sentinel-1C and its twin Sentinel-1 D. Airbus Defence and Space is responsible for both radars.
Next step in the acceptance test sequence of the SAR instrument (complete antenna with the antenna electronic subsystem built by Airbus Portsmouth, UK) is a functional and performance test campaign, planned to run until end of October 2020. Finally the antenna’s radio frequency characteristics will be checked before the instrument is shipped to Thales Alenia Space for platform integration. Copernicus Sentinel-1C is set for launch in 2023.