LSTM (Land Surface Temperature Monitoring) is a mission, set to join the Copernicus Sentinel system in 2028. It will provide high-resolution land surface temperature data to support sustainable agriculture.

The mission’s primary objective is to monitor evapotranspiration (ET) at the level of individual fields – optimised for European agriculture, but globally applicable. Capturing fine-scale variations in land surface temperature (LST) will enable more precise estimates of water productivity in agricultural settings and improve drought forecasting to help combat land degradation.

Figure 1: LSTM satellites operating in low-Earth polar orbit
 

The two LSTM satellites will operate in a low-Earth polar orbit, each revisiting the same location every four days, and together providing coverage every two days.

They will generate thermal maps of the Earth's surface and evapotranspiration rates every 1 to 2 days—with a resolution 400 times finer than than currently available for such short revisit time.

The mission’s two satellites have an expected operational lifetime of 7.5 years.
 

How it works: The LSTM Instrument

The LSTM satellite instrument operates across 11 spectral channels extending from visible to infrared wavelengths.

Six of the 11 channels operate in the solar spectrum (457.5 nm to 1.655 µm), while five operate in  thermal infrared (8.51 to 12.235 µm).

It scans the Earth's surface using a rotating mirror to cover the target  observation area. A full scanning cycle takes 5.58 seconds.

The mirror captures the light from the Earth and redirect it towards the optical system which images  the signal on three sensors, each dedicated to specific wavelength ranges (visible, short-wave infrared  and thermal infrared). The optical instrument split the signal into different channels thanks to an  arrangement of dichroic beam splitters and narrow band filters, while reducing unwanted reflections  (aka ghost images).

The 3 detectors are accommodated within their own focal planes called:

• Ambient Focal Bench (AOB) for VNIR-0, VNIR-1, and VNIR-2 channels;
• Passive Optical Bench (POB) for VNIR-3, SWIR-1, and SWIR-2 channels;
• Cold Optical Bench (COB) for thermal infrared channels TIR-1 to TIR-5.

Figure 2: Field of view of the LSTM instrument and related spectral bands. [Credits: ESA]

 

Applications:

Water on Earth is unevenly distributed between saltwater and freshwater sources.  Around 97% is saltwater, found mainly in oceans, while just 3% is freshwater, most  of which is stored in icecaps and found in groundwater.

Freshwater Source Breakdown:

• Icecaps and Glaciers: 68.7%
• Groundwater: 30.1%
• Surface Water: 0.3%
• Other sources: 0.9%

Surface Water Distribution:

• Lakes: 87%
• Swamps: 11%
• Rivers: 2%

Groundwater provides nearly 99% of the world’s unfrozen freshwater. It accounts  for a third of total global water use, supplies domestic water to almost half the  world’s population, and supports nearly half of all global irrigation.

In the EU, groundwater supplies 65% of drinking water and 25% of irrigation water.  However, it is under pressure from over-extraction and climate change, and once  polluted, is difficult to clean.  
 

Figure 3: LSTM observation map
 

Key Insights: Agriculture & Water Stress

• Agriculture is the world’s largest consumer of freshwater—and will remain so.
• There is 60% less freshwater available globally than 50 years ago.
• Sustainable agriculture is crucial for global food security.
• Freshwater availability is increasingly threatened by climate change and human activity.

Evapotranspiration (ET)—the combined process of water evaporating from soil  and moisture released from plants (transpiration)—is a key factor in both crop and  water management. Effective monitoring and understanding of ET are vital to  support sustainable farming practices and environmental stewardship.  
 

The Benefits of Monitoring ET

• Early stress detection: identifying crops not getting enough water.
• Monitors crop growth: tracking plant development and health.
• Optimisation of farming practices: improving irrigation and cultivation methods.
• Enhanced predictions: providing more accurate yield forecasts.
• Efficient seed production planning: helping manage seed supply.
• Improved fertilisation strategies: boosts efficiency of nutrient use.
• Early plant health diagnosis: prompt detection of disease and nutritional deficiencies.
• Actionable field-level data: enabling decisions for precision agriculture (agronomy).
• Timely pest detection: identifies infestations for early intervention.
• Identifies field performance: highlighting underperforming fields for targeted action.
• Crop prioritisation: directing farming resources where needed most.
• Improved input management: optimising how seeds, fertiliser and resources are sourced and supplied.
• Supporting sustainability: promoting responsible use of water and resources.
• Better crop-soil matching: aligning crop choice with soil type.
• Strengthening food security: improving agricultural resilience to changing conditions.
• Improving water productivity: making agricultural water use more efficient.