Introduction
Europe’s radar constellation has reached a pivotal point as the newest satellite joins the fleet in full‑scale service. This development not only solidifies a decade‑long investment in synthetic‑aperture radar (SAR) technology but also expands the range of data available for climate, disaster‑response and security applications worldwide.
Sentinel‑1D goes live: A milestone for Europe's radar mission
The Copernicus Sentinel‑1D spacecraft, launched in November of last year, has now completed its demanding in‑orbit commissioning and entered full operational status. With all four Sentinel‑1 assets active, the flagship radar program achieves a historic benchmark that reflects more than a decade of European ambition in Earth observation.
When the first satellite, Sentinel‑1A, lifted off in 2014, it inaugurated not just a single mission but the entire Copernicus framework—the EU’s dedicated Earth‑monitoring component.
Its reliable performance proved that Europe could consistently supply high‑quality observations for a suite of Copernicus services and beyond.
The original architecture envisioned a twin‑satellite constellation positioned 180° apart for optimal global coverage, leading to the 2016 launch of Sentinel‑1B alongside its predecessor.
After a technical fault forced Sentinel‑1B into safe mode in August 2022, the program rebounded with the 2024 launch of Sentinel‑1C, restoring the pair, and followed up a year later with Sentinel‑1D.
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Acquired on April 13, 2014, at 23:57 GMT (14 April at 01:57 CEST) by Sentinel-1A, this image shows a transect over the northern part of the Antarctica Peninsula. It was acquired in the satellite's 'strip map' mode with a swath width of 80 km and in dual polarization. The colors indicate how the land, ice and water reflect the radar signal differently. Credit: European Space Agency -
This image from Sentinel-1A's radar shows the metropolitan area of Portugal's capital, Lisbon. Flowing in from the upper-right corner is the Tagus River. The river flows west through Portugal, emptying into the Atlantic Ocean at Lisbon. Its estuary—visible at the centre of the image—is a natural reserve and Ramsar Wetland of International Importance. With extensive mudflats, saltmarshes, reedbeds and human-made salt pans, the area is important for around 16 species of wintering or staging waterbirds, numerous species of breeding birds, and the European otter. Activities outside of the reserve include fishing, shellfish collecting and agriculture, as we can see by the geometric shapes of agricultural plots. Lisbon's city centre sits on the northern shore of the Tagus River, and is visible by the bright radar reflections from buildings and other structures. We can also see the reflections from the suspension bridge that connects Lisbon to Almada on the southern shore. Further east, though not as clear, is the Vasco da Gama Bridge, the longest in Europe, at 17.2 km. Credit: Copernicus data/ESA (2014) -
Sentinel-1 radar data show ground displacement of the San Francisco Bay Area. Hot spots are clearly observed, including the Hayward fault running north–south of the central-right side of the image. Subsidence of the newly reclaimed land in the San Rafael Bay on the left is also visible, while an uplift of land is visible in the lower right, possibly a result of a recovering groundwater level after a four-year long drought that ended in autumn 2015. Credit: Contains modified Copernicus Sentinel data (2015–16) / ESA SEOM INSARAP study / PPO.labs / Norut / NGU
The mission supplies high‑resolution SAR imagery that penetrates clouds and operates day and night. Researchers, policymakers and emergency managers rely on this data to track natural hazards, sea‑ice dynamics, ground deformation and forest loss across the globe.
Equally impressive is the longevity of the record: the fleet is on track to deliver nearly twenty years of uninterrupted radar observations, reinforcing Europe’s leadership in climate‑change monitoring and providing a robust foundation for long‑term scientific studies.
Beyond data acquisition, Sentinel‑1C and Sentinel‑1D introduce a pioneering separation system designed to mitigate orbital debris, underscoring ESA’s and the European Commission’s dedication to sustainable space operations.
With the first‑generation constellation now fully commissioned, ESA and the European Commission are already looking ahead.
ESA’s Sentinel‑1 Mission Manager, Nuno Miranda, remarked, “Sentinel‑1 began as a trailblazer. With the successful commissioning of Sentinel‑1D, it now stands as a cornerstone—reflecting Europe’s achievements while serving as a launchpad for what comes next.”
He added, “For several years we have been advancing a follow‑on mission—Sentinel‑1 Next Generation—intended to guarantee continuity of measurements well into the mid‑2030s and beyond. These future satellites will provide enhanced performance and new capabilities, building on the legacy of their predecessors while addressing emerging scientific and societal needs.”
Key concepts
Remote sensing Artificial satellites Space debrisProvided by European Space Agency
Conclusion
The activation of Sentinel‑1D completes a four‑satellite radar constellation that delivers continuous, all‑weather Earth monitoring. This milestone not only expands the volume and reliability of SAR data but also demonstrates Europe’s commitment to sustainable space practices and long‑term climate stewardship. As the Next Generation platform prepares for launch, the legacy of Sentinel‑1 will continue to underpin critical environmental insights for decades to come.
Source credit: Phys.org
Image credits:
- Image 1 - credit: Phys.org
- Image 2 - credit: Phys.org
- Image 3: Sentinel-1D was launched on Europe’s heavy-lift rocket Ariane 6 on flight designated VA265. Credit: ESA-CNES-ARIANESPACE/Optique vidéo du CSG–P. Piron - credit: Phys.org
- Image 4: Acquired on April 13, 2014, at 23:57 GMT (14 April at 01:57 CEST) by Sentinel-1A, this image shows a transect over the northern part of the Antarctica Peninsula. It was acquired in the satellite's 'strip map' mode with a swath width of 80 km and in dual polarization. The colors indicate how the land, ice and water reflect the radar signal differently. Credit: European Space Agency - credit: Phys.org
- Image 5: This image from Sentinel-1A's radar shows the metropolitan area of Portugal's capital, Lisbon. Flowing in from the upper-right corner is the Tagus River. The river flows west through Portugal, emptying into the Atlantic Ocean at Lisbon. Its estuary—visible at the centre of the image—is a natural reserve and Ramsar Wetland of International Importance. With extensive mudflats, saltmarshes, reedbeds and human-made salt pans, the area is important for around 16 species of wintering or staging waterbirds, numerous species of breeding birds, and the European otter. Activities outside of the reserve include fishing, shellfish collecting and agriculture, as we can see by the geometric shapes of agricultural plots. Lisbon's city centre sits on the northern shore of the Tagus River, and is visible by the bright radar reflections from buildings and other structures. We can also see the reflections from the suspension bridge that connects Lisbon to Almada on the southern shore. Further east, though not as clear, is the Vasco da Gama Bridge, the longest in Europe, at 17.2 km. Credit: Copernicus data/ESA (2014) - credit: Phys.org
- Image 6: Sentinel-1 radar data show ground displacement of the San Francisco Bay Area. Hot spots are clearly observed, including the Hayward fault running north–south of the central-right side of the image. Subsidence of the newly reclaimed land in the San Rafael Bay on the left is also visible, while an uplift of land is visible in the lower right, possibly a result of a recovering groundwater level after a four-year long drought that ended in autumn 2015. Credit: Contains modified Copernicus Sentinel data (2015–16) / ESA SEOM INSARAP study / PPO.labs / Norut / NGU - credit: Phys.org
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