The end of Sentinel-1B?

The situation “does not look very good” for the Sentinel-1B satellite of the EU’s Copernicus Earth observation programme, confirmed European Space Agency (ESA) Director General Josef Aschbacher and Simonetta Cheli, head of ESA’s Earth observation programmes, at the end of the institution’s Council meeting on Thursday 17 March.

Official update from ESA

This remark came shortly after an official update on the ESA and Copernicus websites on 25 February, saying “Following the previous news on the Sentinel-1B anomaly that occurred on 23 December 2021, very detailed investigations related to the satellite power system’s affected unit are still on-going.

The anomaly is related to a 28V power regulated bus that supplies power to the SAR electronics subsystem. The reactivation of both the main and redundant power regulators of this 28V bus have not been successful so far.

Whereas good progress has been made on the investigation of 18 identified possible failure scenarios linked to the affected power unit, at this stage the root cause of the anomaly has not been clearly identified. Satellite system level analyses are conducted in parallel, with the aim to perform new recovery attempts of the unit.

The satellite remains under control, the thermal control system works properly, regular orbit control manoeuvres are routinely performed.

Sentinel-1 users should assume a long-term unavailability of data provision (several months). It is however too early to consider a permanent unavailability of Sentinel-1B.”

Option to move Sentinel-1C launch forward

In January, ESA considered moving up the launch of the new SAR satellite, Sentinel-1C, to compensate for the potential loss of Sentinel-1B. The mission currently is scheduled for launch in the middle of 2023 although the satellite itself would be ready for launch after a flight acceptance review scheduled for as early as October 2022.

Cheli confirmed that Sentinel-1C would be ready for launch in October but said that ESA had not yet decided if the launch could be moved up. “We are assessing, in the current situation, options with Arianespace for launch. We are looking at the earliest options because we want to support the users.”

War in Ukraine getting in the way

A problem for any effort to move up the Sentinel-1C launch is the Russian decision to halt Soyuz launches from French Guiana, requiring five European missions that planned to fly on that rocket there to look for alternative vehicles. That would include the Vega C, the rocket currently planned to launch Sentinel-1C. The Vega C also faces concerns about access to a Ukrainian-built engine for its upper stage, leading ESA to examine options to replace it with an alternative that could affect future launches.

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