By Feng Hua, People’s Daily
China’s first solar exploration satellite named Xihe was sent into space aboard the country’s Long March-2D carrier rocket from the Taiyuan Satellite Launch Center in north China’s Shanxi province on Oct. 14.
The satellite is expected to fill in the gap in high-quality observation data on the source regions of solar eruptions by conducting the world’s first space exploration of solar Hα spectral imaging.
The sun-probing science and technology experiment satellite, whose main scientific payload is a solar space telescope, weighs 508 kg and has a designed lifespan of three years. It will operate in a sun-synchronous orbit at an altitude of 517 km and with an inclination of 98 degrees, which allows it to go over Earth’s North and South Poles and carry out 24-hour continuous observation of the sun.
The solar Hα spectral line is one of the most useful spectral lines for the study of the responses of the photosphere and chromosphere to solar activities.
Through data analysis of the spectral line, scientists can get information about physical changes in the sun during solar eruptions, such as its atmospheric temperature and velocity, and study the dynamic processes and physical mechanisms of solar eruptions.
With the rapid development of aerospace technology, more than 70 satellites have been sent into space globally for solar observation since the 1960s. They have focused on observational studies of sunspots, solar flares, and coronal mass ejections.
“Exploring and studying solar activities and coming up with countermeasures can reduce or avoid their adverse impact on the Earth,” said Zhao Jian, director of the Earth Observation System and Data Center of the China National Space Administration (CNSA), who believes it absolutely necessary for China, a major country in aerospace, to carry out solar exploration in time.
The country has formulated two solar exploration projects, which were named after Xihe, the sun goddess in charge of time and calendar in ancient Chinese mythology who has been well known as the mother of the sun, and Kuafu, a giant in Chinese mythology who chased after the sun, according to Zhao, who said the projects represent China’s solutions and contributions to solar exploration.
While the recently launched satellite Xihe represents China’s first step toward solar exploration, the Kuafu mission is designed to develop and launch another solar observation satellite—the Advanced Space-Based Solar Observatory. As part of the space-science pilot project of the Chinese Academy of Sciences (CAS), the Kuafu mission is scheduled to be launched in 2022.
The successful launch of Xihe marks China’s official entry into the era of solar exploration, Zhao said, adding that the satellite bears great significance as it will conduct the world’s first space exploration of solar Hα spectral imaging and involve new methods and new technologies for astronomical velocity measurement and navigation based on spectral information.
Solar exploration has become a hotspot of global space exploration missions. China ranks second in the world in terms of the number of published research papers on solar observation, but all the satellite-generated data used by Chinese scientists came from foreign spacecraft, according to Zhao.