ESA considering moving up radar satellite launch after Sentinel-1B malfunction

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WASHINGTON — The European Space Agency is considering accelerating the launch of a new Earth science satellite after an existing one malfunctioned last month and remains out of service.

Sentinel-1B, a radar imaging satellite launched in April 2016, malfunctioned Dec. 23. Shortly after the anomaly, ESA said they expected to take up to two weeks to restore the satellite to service. However, in a Jan. 7, update, officials said the malfunction was caused by a “potential serious problem related to a unit of the power system” on the spacecraft.

Sentinel-1B remains out of service. In a Jan. 14 update, ESA said that efforts to reactivate the power system on the spacecraft were not successful. “All necessary investigations to identify the root cause and possibly fix the issue are on-going,” ESA stated, noting that other systems on the spacecraft were functioning, including the ability to control its orbit.

At a Jan. 18 press conference, ESA Director General Josef Aschbacher said both the main power system for the spacecraft’s antenna and a redundant unit on the spacecraft failed at the same time. “We do not know yet the root cause of it,” he said. “This is quite strange.”

He said efforts continue to try to fix the problem. However, he did not estimate how long it might take to either correct the problem or write off the satellite.

Sentinel-1B was built by Thales Alenia Space, with Airbus Defence and Space providing the C-band synthetic aperture radar (SAR) instrument. It is identical to Sentinel-1A, which launched in April 2014 and remains in service beyond its original seven-year life.

Aschbacher said that SAR imagery that Sentinel-1A and -1B provide are in high demand. Sentinel-1A, for example, provided the first images of what was left of the volcano Hunga Tonga-Hunga Ha’apai after a devastating Jan. 15 eruption that sent a tsunami across the Pacific Ocean. The spacecraft’s radar instrument could see the remnants of the volcano while the area was still cloaked in clouds from the eruption.

“On the one side, it shows how essential Sentinel-1B is, or the Sentinels all together,” he said. “Users are really coming to us now and asking us to find solutions.”

One near-term solution is to buy data from other spacecraft. “We’re looking into compensating the loss of Sentinel-1B data through other data that we buy commercially, particularly from Canada,” he said. Canadian company MDA operates the Radarsat-2 satellite, while the Canadian Space Agency operates the three Radarsat Constellation Mission spacecraft. Aschbacher said another option would be to buy L-band and X-band radar imagery from other satellites.

As part of the overall Copernicus program, which is jointly run by ESA and the European Union, two new radar imaging satellites, Sentinel-1C and -1D, are in development. Sentinel-1C is scheduled to undergo a flight acceptance review in October before a launch currently scheduled for some time in 2023.

Aschbacher and other ESA officials suggested that launch could be moved up if Sentinel-1B cannot be restored. “We’re now looking into launching them as soon as we can,” he said of Sentinel-1C and -1D.

Simonetta Cheli, director of Earth observation at ESA, said that if the investigation into the Sentinel-1B malfunction doesn’t require any design changes to Sentinel-1C, ESA would be ready to launch Sentinel-1C at any time after the October flight acceptance review. “The current launch date is mid-’23 for -1C, so we would look for any opportunity for potentially launching earlier,” she said. “We don’t have an option yet.”

Daniel Neuenschwander, director of space transportation at ESA, said the launch manifest will depend on the date and outcome of the inaugural flight of the Vega-C, currently scheduled for May. “I see an opportunity at the end of ’22,” he said, with some contract modifications required to support an earlier launch.