Artist rendering of the Landsat 9 satellite over Earth.
Image courtesy of NASA/Ross K. Walter
One of the key benefits of Earth Observation (EO) is the principle of data continuity – this is having uninterrupted, consistent, long-term datasets available over large areas. This is critical for a variety of reasons, such as understanding what is happening on the Earth, under the ocean and in the atmosphere; monitoring the climate and forecasting the future; providing machine learning and AI with training data to enable them to learn; and providing baseline data for decision making and supporting disaster monitoring.
However, this cherished principle of data continuity is easy to lose: if something goes wrong with a satellite and it stops collecting data then continuity starts to be lost, or if old satellites are not effectively replaced, again data continuity can be lost. Therefore, it is heartening to have two announcements in recent weeks highlighting progress on the next missions for two of the world’s key EO datasets, namely Landsat and Sentinel-1.
Landsat-10
Landsat-10 will be the latest in a line of satellites, which were first launched in July 1971, providing over 50 years of dataset continuity, although the spatial resolution and spectral bands have been enhanced over time.
The new Landsat-10 satellite, which is a joint NASA/USGS mission, is forecast to be launched in 2031 and is expected to deliver the next step change for the dataset. The spatial resolution for the new mission will be in the range of 10 to 20 metres depending on mode, against the current 30 metres; and it will offer 26 spectral bands – including 21 in the Visible and Shortwave Infrared range and 5 in the thermal-infrared range – an increase on the 11 bands currently collected by Landsat-8 and -9. The 26 spectral bands will cover the existing 11 ‘heritage’ bands to maintain data continuity, alongside five complementary bands aligned with European Space Agency’s (ESA) Sentinel-2 satellite, and 10 new bands.
The Southwest Research Institute’s (SRI) work on the mission was highlighted in a recent article as they are working on the electronics, flight software, and control technology to regulate the instrument’s temperature and position the camera’s mirrors. The electronics include systems to compress captured data before it is transmitted back to Earth, no easy task when it is estimated that Landsat-10 will process approximately 1.8 gigabits of compressed data each second. SRI have completed the preliminary design review and are currently building a prototype unit; in addition, they are also developing operational and interface simulators to mimic payload behaviour to help understand the data available to scientific campaigns.
It is exciting to see how the design and build of Landsat 10 is coming along, and although five years until launch seems a long time, in the space sector this can pass quickly, and it will be interesting to see progress in the coming years.
Sentinel-1 Next Generation
In a similar vein, it has been recently announced that ESA has awarded Thales Alenia Space the contract for the development of two Sentinel-1 Next Generation satellites. Sentinel-1 is a synthetic aperture radar (SAR) that operates as a twin constellation. Originally, Sentinel-1A was launched in April 2013 and its twin Sentinel-1B in April 2016. The follow-on missions of Sentinel-1C and Sentinel-1D were launched in December 2024 and November 2025, respectively. The first of the Sentinel-1NG satellites is forecast to launch in 2034.
Similarly, to Landsat-10, the Sentinel-1NG satellites will be a step change for the instrument. It is expected to offer improved spatial resolution reaching 5 m by 5 m compared to the current 5 m by 20 m. The satellites’ C-band SAR will have a large, active, phased-array planar antenna measuring 13.6 m x 0.94 m and according to Thales Alenia Space this will enable image resolution to be improved up to four times compared to existing satellites and provide a larger observation area with coverage expected to be extended into the polar regions.
This new contract should, hopefully, continue the Sentinel-1 radar dataset providing capability for environmental change monitoring, supporting disaster response and evidence-based decision-making.
Conclusion
Data continuity is critical for scientists, researchers and companies using data, and it is encouraging to see major space agencies progressing with the planning and development needed to continue their uninterrupted datasets.
