Commercial constellations of small satellites for Earth remote sensing

In the development of Earth remote sensing (ERS) over the last decade, small spacecraft constellations owned by private companies have played a leading role. The analysis of these constellations carried out in this study allowed one to identify trends in their development for the coming years and possibilities for data collection and processing. Since 2011, a many-fold increase in the number and size of commercial constellations has been observed. It is expected that by the end of 2025 the number of constellations will have reached 81, which is almost 12 times greater than in 2015. The number of multispectral optical imaging satellites is growing at the highest rate. The largest number of new constellations will be involved in thermal infrared imaging and hyperspectral optical imaging. In the number and size of constellations, the leading countries are the USA and China, and the leading companies are Planet Labs (USA) and Chang Guang Satellite Technology (China). Although the number of countries developing their own small-satellite constellations is steadily increasing, the constellations of the leading countries are growing at a higher rate. Two thirds of the multispectral optical imaging constellations are designed to collect data with a spatial resolution greater than 1 m, while three companies collect data with a 30 cm resolution. The number of radar satellites is increasing, while the number of constellations is almost unchanged. Most of the radar satellites work in the X-band with a resolution up to 50 cm, while ICEYE (Finland/USA) and Umbra-SAR (USA) offer radar data with a 25 cm resolution. The use of very low orbits to improve the quality of imagery is under active development. Investments into extraterrestrial imaging to track space objects in near-Earth orbits to prevent possible threats to satellite constellations are increasing. The introduction of onboard data processing facilities and successful experiments on laser communication between satellites open avenues for obtaining targeted ERS information in near-real time. The use of GNSS signals for ERS purposes has become widespread, thus resulting in constellations of dozens of small commercial weather satellites.