The FY-3E Solar SSIM, part of the payload of the Fengyun-3E satellite, was launched with the Long March-4C carrier rocket on July 5, 2021 from the Jiuquan Satellite Launch Center, and started working on Aug 31.

SSIM is designed to obtain high-precision and fine-spectrum irradiance data in the ultraviolet-visible-shortwave infrared band of the extraterrestrial sun, and to monitor the relevancy of minute changes of the solar spectrum to the earth, including the structure of its atmosphere, its surface temperature, natural weather and climate change.

From the solar spectrum information obtained by the FY-3E SSIM, the Fraunhofer lines, a set of spectral absorption lines named after the German physicist Joseph von Fraunhofer, can be clearly observed with all their intricate details.

It’ll be of great scientific significance for Observation and research of the solar spectrum. The solar radiation is the most important external energy source to the earth. It determines the thermal structure and composition of the earth’s atmosphere. 99% of all solar energy is concentrated in the ultraviolet-visible-infrared band. Radiation in the ultraviolet band can change the distribution of molecules in the atmosphere, causing chain chemical reactions, especially affecting the formation of ozone in the stratosphere, and providing the main heat source in the middle atmosphere. Radiation in Visible and near-infrared band can reach the lower atmosphere and even the earth's surface, causing a rise in the temperature.