In 2014, the first Sentinel-1 satellite was launched. Over the past decade, the Sentinel-1 constellation has been widely used for tracking sea ice, monitoring land subsidence, responding to floods and earthquakes, performing InSAR deformation analysis, and supporting ocean remote sensing. Many remote sensing and GIS researchers have even relied on its data for their theses.

However, satellites have finite operational lives. Sentinel-1B was retired earlier due to a power supply failure, and Sentinel-1A will also end its mission this month. Fortunately, Sentinel-1D, launched last year, completed its in-orbit commissioning in May 2026 and now forms a dual-satellite constellation with Sentinel-1C, temporarily easing the application pressure. Still, the demand for next-generation capabilities is urgent.

A Major Deal at the Berlin Air Show

On June 10, at the ILA Berlin Air Show, the European Space Agency (ESA) formally signed a contract with Thales Alenia Space to develop two next-generation satellites for the Copernicus programme: Sentinel-1 NG (Next Generation). The initial contract is valued at approximately €700 million, with the total project cost expected to reach $1.15 billion.

Fourfold Resolution, Extended to Polar Regions

According to available information, the NG version will feature a new SAR instrument with a 13.6 m × 0.94 m active phased-array antenna, coupled with multi-channel acquisition electronics. Geometric resolution is expected to improve from 5 m × 20 m to 5 m × 5 m, with wider swath coverage and denser revisit times. An enhanced quad-pol mode will strengthen land monitoring, and a new sea-ice observation mode will extend coverage to polar regions.

Sentinel-1 NG will continue to support operational Copernicus services in environmental protection, climate monitoring, emergency management, and maritime surveillance, covering ocean and sea-ice dynamics, land-surface change, rapid disaster assessment, deformation tracking, and deforestation monitoring.

A Decade-Long Wait

For GIS practitioners, the future free and open radar basemaps and InSAR products will offer improved resolution and revisit frequency. Does that mean new data for your thesis? Don't get too excited just yet. According to current plans, the first launch may be postponed to around 2034, meaning the operational Sentinel-1C and -1D will have to endure for nearly another decade. (If you are a freshman now, you might have a chance by the time you finish your PhD.)

Chinese SAR Satellites: A Viable Alternative

If you are working in this field but current Sentinel data cannot meet your needs, it is worth looking at Chinese SAR satellites, which have developed along a distinct path.

The most direct counterpart to Sentinel-1 is the Gaofen-3 series. GF-3-01, launched in 2016, was China's first C-band fully polarimetric SAR satellite. GF-3-02 and GF-3-03 followed in 2021 and 2022, and the three-satellite constellation now achieves a global average revisit interval of about 4.8 hours. With a maximum resolution of 1 metre and over 12 imaging modes, it serves both land and ocean applications, including oil-spill monitoring, typhoon tracking, and disaster response. In C-band strip-map mode, the fine strip resolution reaches 5 metres – comparable to the NG target – while the spotlight mode offers even higher resolution.

For InSAR deformation monitoring, the LuTan-1 (LT-1) twin satellites are a more tailored option. Launched in 2022, LT-1A and LT-1B form China's first L-band differential interferometric SAR constellation, achieving 3-metre resolution, up to 400 km swath width, and a 4-day revisit interval after constellation operation, dedicated to observing surface subsidence, earthquakes, and landslides.

Another distinct approach is the Ludi Tancha-4-01 (LT-4-01), launched in 2023. It is the world's first geosynchronous-orbit SAR satellite, operating in L-band, reducing revisit times from days (low-Earth orbit) to hours for the same area, with swath widths reaching thousands of kilometres, primarily designed for rapid disaster prevention and response.

Summary

In any case, the signing of Sentinel-1 NG is good news for the remote sensing and GIS community, as it promises more free and open globally standardised products under the Copernicus framework. Nevertheless, Chinese satellites should not be overlooked. Gaofen-3, LuTan-1, and Ludi Tancha-4 each have their strengths in resolution, revisit, and band combinations, and they are by no means inferior. For remote sensing and GIS professionals, the data options for research, operational monitoring, and other scenarios are growing ever more diverse.

What SAR satellite data are you currently using? Feel free to share in the comments.