Monitoring land surface temperature from space -constellr HiVE - new perspectives for environmental monitoring
Authors: Spengler Daniel , Ibrahim Elsy , Chamberland Nicolas , Pregel Hoderlein Ariadna , Berhin Jonas , Zhang Tianran , Taymans Matthieu 
Published: March 2024

The importance of thermal remote sensing satellite data has become increasingly recognised for environmental monitoring in the recent years. Specifically, in providing valuable information on the earth&#8217;s land surfaces and plant canopies, which can be used to diagnose water stress and drought conditions. Thermal data, with its unique capacity to capture temperature variations, brings an unexplored added value for understanding processes. Thermal imaging also provides much-needed information on soil moisture status in regions where data are scarce. The use of thermal remote sensing data has been widely recognized as a contributor to large-scale environmental monitoring. It has enabled getting more insights from a variety of resource management domains, including agriculture, forestry, geological resources, water resources, cryosphere, atmosphere, and analytics for climate change.Unfortunately, current thermal satellite data are either only available in very high to high temporal resolution or in low spatial resolution (>1,000m) respectively from geostationary or sun-synchronous satellites, which have a low temporal resolution and moderate spatial resolution of 30-100m. Such data are therefore only of limited suitability when regular monitoring of small-scale environmental factors is required.constellr develops a constellation of new state-of-the-art satellites covering the visible, near infrared, and thermal infrared parts of the spectrum at high-resolution, planned for launch by the end of 2024. The HiVE (High-precision Versatile Ecosphere monitoring mission) constellation comprises micro-satellites in the 100 kg class, orbits in a sun-synchronous plane at an altitude of 550 kilometers. With a remarkable 1-day global temporal resolution (5 sat from 2026), 30 meters spatial resolution, and up to 1.5 K absolute temperature accuracy, HiVE is uniquely equipped with a cryo-cooled&#160; thermal detector to provide accurate and timely data for environmental monitoring. Leveraging its proprietary data, imagery from public missions, and strong remote-sensing expertise for data fusion, harmonization, and analytics, constellr offers timely and highly scalable solutions.&#160;To ensure the interoperability of HiVE data with existing and upcoming thermal satellite missions,&#160;constellr has developed a proprietary LST retrieval algorithm. Based on Top of Atmosphere (TOA) radiance and atmospheric condition, emissivity and temperature estimations are performed. This enables capturing the vegetation dynamic related to specific vegetation types and growth stages. To further reinforce its monitoring capacity constellr leverages existing thermal infrared sensors and performs a spatial and spectral harmonization of the data to provide a consolidated LST product at 30m resolution (LST30).&#160;For the HiVE satellites we will present the mission concept, status, and planned validation activities. Furthermore, the added value of high resolution LST data at 30m will be presented with diverse use cases.