The European Space Agency (ESA) has awarded a contract to Thales Alenia Space, a joint venture between Thales (67%) and Leonardo (33%), to perform the mission consolidation study of the SIRIUS mission (Space Based Infra-Red Imager for Urban Sustainability), in the frame of the Scout missions, part of ESA's Earth Observation FutureEO programme. The SIRIUS mission aims to observe European cities from space using thermal infrared (TIR) data products, which allow the measurement of the temperature of objects from a distance. The objective is to understand how Urban Heat Islands modify the local climate. Urban Heat Islands are areas in cities where higher temperatures are recorded than in the surrounding rural areas, as a result of heat accumulation on impermeable surfaces, sparse vegetation, and human activity. 

Fostering urban sustainability In a global context marked by climate change and the accelerated growth of cities, urgent challenges arise for urban resilience and environmental sustainability. Of the 8.2 billion people currently inhabiting the planet, more than half live in urban environments, and this figure is expected to rise to 6.5 billion by 2050, reaching two-thirds of the population. Rapid urban expansion can exacerbate existing vulnerabilities and generate new threats to health, the environment, and well-being, especially when it occurs without adequate planning. 

One of the most problematic consequences of accelerated urbanization is the increase in Urban Heat Islands. Generally, cities register higher temperatures than rural areas, especially at night, when the difference can be as much as 12°C. This phenomenon, intensified by the effects of climate change, not only impacts physical health and psychological well-being but also influences daily habits and economic dynamics. Additionally, it can lead to a significant increase in morbidity and mortality rates, as well as a notable rise in energy consumption in urban areas. 

Having accurate information about surface temperature in urban environments through heat maps obtained frequently and sustained over time is key to understanding the phenomenon of Urban Heat Islands. This data becomes an essential tool for guiding decisions in urban planning and the development of effective climate policies. 

Scout missions are intended as an agile, fast and low-cost approach to prove new concepts in Earth observation, with a scientific research focus. Their total value is limited to 35 million euros, including launch, and their development must be completed within a maximum period of 3 years, from the start of implementation to flight acceptance. 

The SIRIUS mission is designed to provide night-time observations of several European cities on a daily basis for a period of three or more years, with a native resolution of 64 meters, perfectly suited to the needs of Urban Heat Islands monitoring. Its rapid development, high resolution, scalable and cost-effective approach relies on the Smart-TIRI instrument developed by Thales Alenia Space. This miniaturized thermal infrared imaging instrument uses an innovative microbolometer-based detection solution, which avoids the need for expensive cooling systems. A prototype of the Smart-TIRI instrument was developed within the framework of the MORERA (Monitoring System for Efficient Irrigation and Agricultural Performance) project with outstanding results.

Besides being responsible for the development of the Smart-TIRI instrument, Thales Alenia Space in Spain is the prime contractor of the SIRIUS mission and leads a consortium of various partners, including the University of Valencia (Spain), whose professor José Antonio Sobrino acts as the scientific lead of the project, playing a crucial role in defining and refining the scientific objectives of the mission and addressing priority scientific questions. Also participating are Kongsberg Nano Avionics (Lithuania), responsible for the small satellite platform based on their flight-proven Nano Avionics MP42H model and its Flight Operations Segment; Thales Alenia Space in France, which will perform mission analysis, support the development of the end-to-end simulator and carry out image quality activities; and the National Institute for Aerospace Technology, INTA (Spain), responsible for the definition of the end-to-end performance simulator.