Among the various types of sounding instruments carried by meteorological satellites, microwave thermometers are one of the most successful payloads and have become standard on polar-orbiting meteorological satellites launched by China, Europe and the United States. According to the assessment of the European Centre for Medium-Range Numerical Weather Forecasting (ECMWF), the global vertical temperature and humidity profile information obtained by satellite microwave sounding is the most valuable information for reducing errors in numerical forecast models, ranked by contribution, exceeding the assimilation effect of any other sounding information including traditional sounders.

Atmospheric sounding by satellite-based microwave remote sensing can work both during the day and night, and is not affected by weather, has the ability to penetrate clouds and rain areas, and can obtain three-dimensional atmospheric temperature and humidity and cloud and rain structure to achieve all-weather earth observation. All these reflect the advantages of microwave remote sensing, so that it plays a unique role in the field of space-based weather detection, but in the past, the microwave detectors carried on polar-orbiting satellites, there are also obvious weaknesses, that is, the revisit time to a place is long, not easy to capture the complete information of some multivariate weather systems. For this reason, by redesigning the microwave instruments loaded on large satellites, and transforming them into relatively simple payloads to be installed on small satellites to carry out high spatial and temporal resolution detection by forming a constellation of multiple stars, it becomes an ideal choice.

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