China’s Long March 8 rocket successful in debut launch

A Long March 8 rocket lifts off from Sunday (U.S. time) from the Wenchang launch base on Hainan Island. Credit: Xinhua

A new Chinese launch vehicle, the Long March 8, has successfully placed five payloads into orbit on its first mission, debuting an expendable booster intended to eventually be outfitted for recovery and reuse.

The Long March 8 rocket took off from the Wenchang satellite launch center on Hainan Island, China’s newest spaceport, at 11:37 p.m. EST Dec. 21 (0437 GMT; 12:37 p.m. Beijing time Dec. 22), Chinese space program officials said.

The medium-lift launcher is the latest in a series of new additions to the Long March rocket family, following the introduction of the Long March 5, Long March 6, and Long March 7 vehicles in recent years.

The Long March 8 is designed to carry a payload of about 9,900 pounds (4.5 metric tons) to a 435-mile-high (700-kilometer) polar sun-synchronous orbit, placing its lift capability between that of the smaller Long March 6 and the more powerful Long March 7. The new rocket fills a gap in Chinese launch capacity between 3 and 4.5 metric tons to sun-synchronous orbit, according to the China Aerospace Science and Technology Corp., or CASC, the primary state-owned contractor for the country’s space program.

The Long March 5 rocket is China’s new heavy-lifter, and the most powerful launcher in the history of the Chinese space program.

The new Long March rockets use non-toxic propellants, with kerosene- and hydrogen-fueled engines to replace the older hydrazine-burning engines used on Long March 2, Long March 3, and Long March 4 rockets.

A Long March 8 rocket lifts off from Sunday (U.S. time) from the Wenchang launch base on Hainan Island. Credit: CASC

China’s new Wenchang launch base on Hainan Island, in the southern part of the country, fronts the South China Sea. Long March rockets launching from Wenchang, such as the Long March 8, drop their spent boosters over the ocean instead of over land.

China’s Long March 8 rocket stands 165 feet (50.3 meters) tall and weighs about 392 tons (356 metric tons) fully fueled for launch, according to the country’s state-run Xinhua news agency.

Two YF-100 engines power the Long March 8’s 11-foot-diameter (3.35-meter) core stage, and a single YF-100 engine is fitted to two 7.4-foot-diameter (2.25-meter) strap-on boosters. The YF-100 engine — also used on Long March 5, Long March 6, and Long March 7 rockets — consumes kerosene and liquid oxygen propellants.

The Long March 8’s cryogenic second stage is driven by two YF-75 engines burning liquid hydrogen and liquid oxygen. The YF-75 engine is also flown on the upper stages of China’s Long March 3 rockets.

Chinese officials approved development of the modular Long March 8 rocket in May 2017, according to CASC. The three-year development cycle — relatively fast for a new rocket in the Long March 8’s class — was expedited by the launcher’s use of engine and booster designs from the Long March 7 and Long March 3 vehicles, CASC said in a statement.

This animation illustrates how engineers plan to land the Long March 8’s core stage and side boosters together. Credit: CASC

The Long March 8 rocket will eventually help China replace its fleet of medium-lift launch vehicles, providing launch services for low Earth orbit satellite constellations and payloads bound for higher altitudes, such as geosynchronous orbit, CASC said.

Chinese engineers have also introduced thrust control technology on the Long March 8 rocket, CASC said, laying a foundation for future augmentations to recover and reuse boosters. Future Long March 8 rockets will be fitted with control fins and legs for vertical landings on an offshore platform, similar to the way SpaceX recovers its Falcon 9 boosters on drone ships.

Engineers plan to land the Long March 8’s core stage and two side boosters as a single integrated unit, using low-thrust propulsion to brake before touchdown.

“Long March 8 will offer a platform for the application of and experiments for recycling, intelligent and automatic technologies,” said Wu Yitian, deputy chief designer of the Long March 8 rocket, in a report published by Xinhua.

The adjustable thrust level in the Long March 8 engines also allows the rocket to throttle down as it passes through the phase of maximum aerodynamic pressure, when it is flying through the dense lower atmosphere at high speed. The adjustment, which is common in U.S. rockets, reduces structural loads on the launcher, Chinese officials said.

On its debut mission, the Long March 8 lifted off with more than a million pounds of thrust and flew south from Hainan Island and jettisoned its first stage and side boosters a few minutes into the flight. The second stage engines injected five payloads into an orbit roughly 310 miles (500 kilometers) above Earth, with an inclination of 97.4 degrees to the equator.

China’s first Long March 8 rocket prepares to roll out to its launch pad before liftoff. Credit: CASC

The Long March 8’s payloads included a top secret Chinese “technology verification satellite” named XJY 7, the largest of the five satellite passengers on-board.

The other payloads included Haisi 1, a 400-pound (180-kilogram) radar Earth-imaging satellite for the Chinese company Spacety, and an experiment-hosting 12U CubeSat named Yuanguang. The Tianqi 8 data relay satellite launched on the Long March 8 rocket to join a fleet of orbiting relay stations designed for Internet of Things services. The Tianqi constellation is owned by Guodian Gaoke, a Beijing-based company.

Another CubeSat — a 6U smallsat named ET-SMART-RSS — was the final payload on the Long March 8 rocket. It was jointly developed by engineers at the Ethiopian Space Science and Technology Institute and Beijing Smart Satellite Space Technology Co. Ltd.

The Chinese-funded, 20-pound (9-kilogram) satellite will provide Earth observation data for users in Ethiopia and China. Ethiopian officials said the partnership will strengthen ties between Ethiopia in “human development” and “technology transfer,” according to China’s Xinhua news agency.

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