China launches orbiting solar observatory

A Long March 2D rocket blasts off with China’s Xihe solar research satellite. Credit: CASC

China successfully launched a half-ton scientific research satellite Oct. 14 to study the violent and sudden physical processes behind solar flares, joining 10 other small payloads on a Long March 2D rocket that also tested grid fins to help guide the expendable booster away from populated areas during its fall back to Earth.

The Long March 2D rocket blasted off from the Taiyuan launch base in Shanxi province, located in northern China, at 6:51 a.m. EDT (1051 GMT) on Oct. 14, according to China’s space agency.

The two-stage, liquid-fueled rocket headed south from Taiyuan and placed the 11 satellites into a polar sun-synchronous orbit at an altitude of approximately 323 miles (520 kilometers).

The rocket employed a grid fin control system on its first stage, the first time such a steering mechanism has been used on a Long March 2D launcher. The grid fins extended from the first stage after the booster jettisoned a few minutes after launch.

The system is designed to reduce the size of the booster’s impact area by more than 80%, according to the China Aerospace Science and Technology Corp., the leading state-owned contractor for China’s space program.

China does not recover and reuse its rockets. Launches from China’s inland spaceports drop their spent boosters over Chinese territory, sometimes near populated areas.

The grid fins make the booster impact site “more precise and controllable” and will “greatly improve the safety environment of the landing area,” CASC said in a statement. China previously tested grid fins on other versions of the Long March rocket family.

The primary payload on the launch was the Chinese Hydrogen Alpha Solar Explorer, or CHASE satellite, China’s first science mission dedicated to observing the sun.

Chinese officials announced a new name for the mission, Xihe, after a public call for ideas. Xihe is a goddess the sun in Chinese mythology.

The Xihe mission, which China’s space agency described as a solar research and technology demonstration satellite, carries a solar telescope tuned to monitor the sun in the hydrogen alpha spectrum. Observations in the hydrogen alpha spectral line see the sun in a deep red color, which is suited to study solar flares, revealing details not visible to telescopes operating in other optical bands.

Solar flares, the largest explosive events in our solar system, are giant eruptions from the sun that send radiation into space. The Xihe mission aims to study the mysterious physical processes that drive solar flares, which scientists say are associated with the sudden release of magnetic energy near sunspots.

The Xihe solar telescope will look for changes in temperatures and velocities of material in the solar photosphere and chromosphere — the visible surface of the sun, and the super-heated gaseous layer just above it.

Chinese scientists say the Xihe mission will explore the dynamic trigger mechanisms that drive solar flares and coronal mass ejections, which can impact Earth and generate geomagnetic storms, affecting communications, electrical grids, and satellite operations.

The Xihe spacecraft, along with several of the mission’s secondary payloads, is attached to the payload adapter of its Long March 2D rocket. Credit: CNSA

The satellite weighs about 1,100 pounds, or 500 kilograms, according to Chinese officials. It uses a new ultra-precise pointing platform that applies “maglev technology” that helps isolate the science payload from tiny spacecraft vibrations, according to the China National Space Administration.

Future Chinese satellites could use similar technology for remote sensing, solar system exploration, and astronomy missions, the space agency said in a statement.

The Chinese space agency approved development of the Xihe mission in 2019. Nanjing University leads the science team. The Shanghai Academy of Spaceflight Technology, a government-run enterprise, developed the spacecraft platform.

The Changchun Institute of Optics, Fine Mechanics and Physics, part of the Chinese Academy of Sciences, developed the Xihe mission’s scientific payload. The science instrument consists of a telescope, a grating spectrometer, and scanning mirrors to focus on specific regions on the sun’s disk, a capability enabled by the satellites fine pointing system.

In a statement, Nanjing University said data from the Xihe mission will be released to domestic and international scientists after calibration.

China plans to launch the Advanced Space-based Solar Observatory, or ASO-S, next year. Chinese officials have said they plan to develop a multi-spacecraft three-dimensional solar observatory in the future.

The Long March 2D rocket that deployed China’s Xihe solar research satellite also released 10 smaller payloads into orbit.

Grid fins on the Long March 2D’s first stage. Credit: SAST

The secondary payloads included the SSS 1 and SSS 2A student-built microsatellites from Beihang University and Shanghai Jiao Tong University. The SSS 1 satellite deployed a coiled extension arm after reaching space.

China Great Wall Industry Corp., which arranges launch services for commercial and international satellites on Chinese rockets, said in a statement that it contracted rides to space for the other eight small payloads.

The other rideshare satellites included the HEAD 2E and 2F spacecraft for a Beijing-based company named HEAD Aerospace, which is deploying a fleet of small spacecraft to track ships and aircraft.

The Tianshu 1 spacecraft will test technologies to augment space-based navigation services. Another satellite, named MOTS, will demonstrate use of a VHF Data Exchange System for Shanghai Lizheng Satellite, testing technology that could be used to relay communications from maritime vessels.

Also on-board the launch was the Golden Bauhinia N2 remote sensing satellite from Hong Kong Aerospace Science and Technology Group, which is developing a constellation of small spacecraft to provide near-real-time, all-weather high-resolution images of the Guangdong-Hong Kong-Macau Greater Bay Area.

Another satellite, named MD 1, developed by Shenzhen Aerospace Dongfanghong Satellite Co. Ltd. is designed to study atmospheric density in low Earth orbit.

The QX 1 satellite, developed by the same company, is an experimental pathfinder for a future constellation of weather monitoring smallsats to obtain data on atmospheric temperature, humidity, and air pressure using occultation measurements of satellite navigation signals.

The Tianyuan 1 from Nanjing University was the final satellite on the Long March 2D launch last week. The suitcase-size spacecraft will test a new type of solid thruster and a micro-propulsion system.

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