ESA announces end of Sentinel-1B mission

Satellite has not provided data since late last year. Operations to remove Sentinel-1B from orbit are already underway, but the satellite is not due to leave orbit until 2023.

The Sentinel-1B satellite has been officially deemed inoperable and its mission terminated. The announcement, made this Wednesday by the European Commission and the European Space Agency (ESA), comes after several attempts to resolve an anomaly detected in the satellite’s power system. Sentinel-1B has not provided data since December 23, 2021.

After confirming in January that a power supply problem was at the root of the loss of data transmission and that the first attempts to resolve the malfunction had failed, ESA would try again the following month. At that time, the Agency assured that there were no problems with “the control system”, but warned that data might not be available for a long period of time.

ESA eventually concluded, following a thorough analysis of this malfunction, that it would be impossible to recover the blockage in the C-SAR Antenna Power Supply unit (CAPS), which is responsible for supplying power to the radar’s electronic subsystem. Having been unable to reactivate the main power regulators, despite several attempts since late last year, ESA eventually considered the Sentinel-1B’s capability lost.

Sentinel-1B, launched on April 25, 2016, was part of the Sentinel-1 series, the first in a total of six, that ESA continues to develop for the European Union’s Earth observation program, Copernicus. This first series now includes only Sentinel-1A, launched two years earlier (2014) and which, like Sentinel-1B, carries on board the SAR radar sensor (synthetic aperture radar) allowing data collection with applications in sectors as diverse as maritime surveillance, subsidence, and infrastructure monitoring or agriculture.

“Sentinel-1A remains in orbit in very good condition, continuing to provide high-quality radar imagery for various applications,” says Simonetta Cheli, ESA’s Director of Earth Observation Programs.


What’s next? 

The preparation phase for removing the satellite from orbit is already underway and is expected to last until the end of March 2023. This process requires a detailed study in the fields of satellite engineering, mission analysis and flight operations, reads the executive summary on the anomaly, made available by ESA.

To cope with the service disruptions caused by this breakdown, the ESA wants to accelerate “the launch of Sentinel-1C,” which is expected to take place in the second quarter of 2023, largely due to the “success of the first flight of VEGA-C,” which took place at the European spaceport in Kourou on July 13.

Although it is not possible to start the removal of Sentinel-1B from orbit while Sentinel-1A operational activities are underway and the launch of Sentinel-1C is being prepared, the process is already in the preparation phase and, according to the executive summary, will start sometime between July and September 2023, and could last “several months.”

The removal from the orbit of this satellite will also reflect the “joint commitment of the European Union and the ESA” to a “clean and responsible space, using the EU’s Space Surveillance and Tracking capabilities”, points out Paraskevi Papantoniou, Director General of the Defence Industry and Space (DG DEFIS), quoted in the same statement.

Until then, “the Copernicus Program will try to meet its needs by optimizing the acquisitions made with Sentinel-1 and by using satellites from other space agencies or service providers,” explains Carolina Sá, responsible for Earth Observation projects at the Portuguese Space Agency, which is also the national delegate for the ESA’s Earth Observation Program and the European Commission’s Copernicus Program.

For now, due to the unavailability of Sentinel-1B data, the revisit capacity of Sentinels with SAR technology is reduced from 7 days to 14 days. “For some applications, such as infrastructure monitoring, the revisit time of only 14 days may not have as much impact, but in other situations such as operational navigation services where data is used for ice detection and route definition, the impact will be more significant,” explains Carolina Sá, which is why the Copernicus program is trying to make up for the absence of data through partnerships or data acquisition from other missions.

Sentinel-1B showed its first image on April 28, 2016, a few days after its launch, capturing an area 250 km wide, which included the Norwegian archipelago of Svalbard.

Portugal Space
3 of August, 2022