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Agriculture and Space: What Capabilities Can Satellites Bring?
23 Oct 2024
Satellites enable the digital capture of vast and diverse agricultural data, which are essential for modern farming. By providing a comprehensive view of Earth's surface, satellites contribute invaluable information on crop health, soil moisture, and vegetation. These data are critical for monitoring growth stages, detecting early signs of stress, and optimising the use of resources such as water and fertilisers.
The Group on Earth Observations Global Agricultural Monitoring Initiative (GEOGLAM) has defined a set of Essential Agricultural Variables, which help to provide insight and actionable information on the state, change and forecast for agricultural productivity.
Observations made by ESA’s Earth Explorer missions and data accessible through the Third Party Mission (TPM) programme provide significant capability to observe these variables.
What kind of data do satellites contribute?
Normalised Differential Vegetation Index (NDVI)
NDVI is calculated from the visible and near-infrared light reflected by vegetation. Healthy, green vegetation absorbs most visible light, and reflects a large portion of the near-infrared light. Unhealthy or sparse vegetation reflects more visible light and less near-infrared light.
Measurements of these reflected values can be used to calculate an index to assess whether the area being observed contains green vegetation. This index can be a useful tool to estimate crop yields and pasture health.
Essential Agricultural Variables: Leaf Area Index, Fractional Cover
Mathematically, NDVI is calculated as:
NDVI = (NIR — VIS)/(NIR + VIS)
NIR = reflection of near-infrared light
VIS = reflection of visible light
Calculations of NDVI result in an index that ranges from -1 to +1. The range of values can be interpreted in terms of vegetation health.
| NDVI Value | Explanation |
| -1 | Since water absorbs more visible and infrared light than it reflects, negative values are generally associated with water bodies. |
| 0 | A value of zero suggests no green vegetation. For example barren land, rock, sand, snow, or urban environments where there is no significant vegetation present. |
| +1 | An NDVI positive value indicates higher possible density of green leaves. While NDVI rarely reaches +1, values close to this figure usually represent dense green foliage. |
Observations for the calculation of NDVI have been collected by a number of missions from which ESA makes the data available, including PROBA-V, SPOT, and WorldView-3.
ESA developed the PROBA-V (Project for On-Board Autonomy - Vegetation) mission to continue the SPOT Vegetation instrument (VGT), which had flown on two successive missions, operating continuously since 1998, and tasked with mapping land cover and vegetation growth across the entire planet.
VGT was first flown on larger satellites (3000 kg SPOT-4 and SPOT-5), while PROBA-V was a much smaller spacecraft (150 kg).
PROBA-V operated from 2013 to 2021, and was downsized even further with the 2023 launch of the 16 kg PROBA-V Companion Cubesat (PV-CC).
VGT is a medium-resolution spectro-radiometer that measures light from different parts of the spectrum to analyse vegetation and soil conditions. Vegetation has a 100 m resolution in four bands in the visible near-infrared (VNIR) and short-wave infrared (SWIR) ranges (blue, red, near infrared, SWIR).
Historical NDVI products from PROBA-V are available within the Level-3 synthesis datasets, which are available in 100 m, 333 m and 1 km spatial resolutions, and on a daily (S1), 5-daily (S5), or decadal (S10) repeat cycle.
NDVI is available in two dataset types: top of atmosphere (TOA) and top of canopy (TOC). TOA data includes atmospheric effects, while TOC is further processed to remove these effects and hence provides more accurate vegetation measurements. PROBA-V Level-3 data are CEOS Analysis Ready Data (CEOS-ARD) compliant, making them easier to analyse.
Users can also access data via ESA’s Third Party Mission programme, including SPOT and WorldView-3.
The SPOT series of missions provide finer resolution (6 m multispectral), multispectral imaging capabilities suitable for applications offering panchromatic and multispectral bands (blue, green, red, and near-infrared (NIR)). WorldView-3 (1.2-3.5 m multispectral) adds an additional near infrared band (blue, green, red, NIR, 8 SWIR), providing improved capabilities allowing for detailed vegetation and soil analysis.
ESA Third Party Missions: SPOT-6, SPOT-7, WorldView-3
The main application driving the development of the PROBA-V mission was to bridge the gap between the SPOT Vegetation missions and Copernicus Sentinel-3. Sentinel-3 carries the Ocean and Land Colour Imager (OLCI), which images in 21 bands across VNIR and SWIR, at a resolution of 300 m. In addition, the Copernicus Sentinel-2 mission carries the Multi-Spectral Imager (MSI), which images in 13 bands across the VNIR to SWIR range, with a maximum of 10 m resolution. Both instruments offer NDVI products, and more information can be found on Sentinel Online (Sentinel-2, Sentinel-3, Sentinel-3 SYNERGY Applications).
Soil Moisture
Soil moisture is a key agricultural parameter, and changes in soil moisture have a significant impact on agricultural productivity. On the macro scale, observations can help improve awareness of flood and drought conditions. It is also key to developing more accurate yield projections by understanding soil conditions.
For agronomists and producers, soil moisture is a critical parameter in determining the timing and projected yield of a crop helping inform decisions at sowing time. For soil science, evaporation rates, surface runoff, infiltration and percolation are dependent on the level of moisture in the soil.
Essential Agricultural Variables: Surface Soil Moisture, Root Zone Soil Moisture
Satellites measure soil moisture through microwave radiometers and Synthetic Aperture Radar (SAR) sensors. The Soil Moisture and Ocean Salinity (SMOS) mission carries the MIRAS instrument (Microwave Imaging Radiometer using Aperture Synthesis). MIRAS is a passive microwave 2D interferometric radiometer, which measures in L-Band (frequency 1.4 GHz / wavelength 21 cm), sensing faint microwave emissions from Earth's surface to map levels of soil moisture, alongside other geophysical variables such as freeze-thaw soil state.
| Product | Description |
| SMOS baseline science products | Level-2 soil moisture datasets are part of the operational baseline products of the SMOS mission. |
| SMOS Near-Real Time (NRT) products | This includes the Level-2 soil moisture product generated using a Neural Network algorithm (in netCDF format), distributed by the SMOS ground segment in near-realtime (within 3-4 hours from sensing). |
| SMOS Soil Freeze and Thaw State | The SMOS Level-3 Freeze and Thaw (F/T) product provides daily information on the soil state in the northern hemisphere based on SMOS observations and associated ancillary data. |
SMOS Mission | SMOS Instrument (MIRAS)
ESA Heritage missions Envisat, ERS-1 and ERS-2 each carried SAR instruments as well. The data from these missions can support change and time-series analyses.
ERS-1 and ERS-2 operated from 1991 to 2000 and 1995 to 2011 respectively, while Envisat operated from 2002 to 2012. Combined with data from SMOS (launched in 2009 and operational as of 2024), this provides over 30 years of soil moisture data.
In addition, the Copernicus Sentinel-1 mission carries a C-band SAR instrument (5.405 GHz), which also offers soil moisture products. More information about Sentinel-1 data can be found on Sentinel Online.
Why does Agriculture Matter?
Agriculture sits at the nexus of humankind’s needs, desires, trade, tension with the environment, and the changing climate. It is increasingly under pressure to meet the growing demand for food as the global population continues to rise, and the global diet continues to evolve.
The world’s population has recently surpassed 8 billion, and the United Nations median projection predicts it will continue to grow, exceeding 10 billion by the 2060s. This growth is putting strain on global agricultural systems.
Changes in the climate are impacting production and increasing its variability, forcing adaptation to meet current needs and assure sustainability. The challenge is ultimately that of balancing increased productivity with sustainable practices. Observations from space have an important role to play in addressing this challenge - supporting food security, providing systematic, sustained, and objective observations.
How Can We Take the Next Step?
PROBA-V User Segment and Mission Exploitation Platform
The PROBA-V user segment is operated by VITO, where a number of PROBA-V products can be accessed. This is complemented by the PROBA-V Mission Exploitation Platform (MEP), providing visualisation and a number of related datasets and derived products. The MEP data offering includes the complete archive from SPOT-VGT, PROBA-V and derived parameters, as well as selected high-resolution products.
ESA Agricultural Virtual Lab
ESA’s Agriculture Virtual Laboratory (AVL) enables researchers to access, share, visualise, process and validate agricultural data sets. Algorithms and workflows developed within the virtual laboratory may be published and shared, enabling collaboration within the community.
The AVL includes a Jupyter Notebook, a visualisation tool, an interface to the Thematic Processing subsystem, and an overview of data and algorithms. The Thematic Processing Subsystem offers an engine for numerous common workflows and tools for agriculture research using a number of tools including Sen2Agri, Sen4CAP, SNAP, gdal, and Orfeo.
Archive and Tasking with ESA Third Party Missions
Image credit: © Maxar Technologies. All rights reserved.
ESA's TPM programme provides access to a portfolio of non-ESA satellite missions. Data from the TPM programme is generally available for free to the scientific, educational, and other non-commercial users with an accepted proposal. Both full archive and tasking access to SPOT-6, SPOT-7, and WorldView-3 is available via this programme.
- SPOT-6 to 7 full archive and tasking
- WorldView-3 full archive and tasking
- WorldView-3 Sample Data
- Explore sample data products from Third Party Missions
SeNtinel Applications Platform (SNAP)
The Sentinel Application Platform (SNAP) is a common architecture for all Sentinel toolboxes, including for SMOS and PROBA-V. The toolboxes consist of a rich set of visualisation, analysis and processing tools for the exploitation of the collected data.
CREODIAS for Land and Agriculture Monitoring Data
CREODIAS provides commercial services for the Copernicus Data Space Ecosystem. The platform provides immediate access to satellite data and services.
The tool enables users to prototype and build their own value-added services and products, providing big-data enabled OpenStack cloud services for data processing, based on a large repository of Earth observation data. This includes a number of datasets, which support agricultural monitoring enabling the calculation of NDVI. It also includes data from SMOS.
CREODIAS for Land and Agriculture Monitoring Data
Learn more about the ESA Agriculture Science Cluster