SpaceX’s Falcon 9, which sent two US astronauts to the International Space Station on the first commercial flight on May 30, wasn’t the only recent milestone in space. China’s 28 year old “golden rocket,” made in Shanghai, also made headlines the next day.

The Long March-2D carrier rocket, developed by the Shanghai Academy of Spaceflight Technology, sent two Satellites into space from the Jiuquan Satellite Launch Center in northwest China’s Gansu Province on May 31.

The Satellites, Gaofen-9 and HEAD-4, were successfully placed in orbit.

As an optical remote sensing satellite, Gaofen-9 is capable of providing photographs with a resolution of about 1 meter. It will be used in land surveys, urban planning, road network design and crop yield estimates, as well as disaster relief. It can also serve projects under China’s Belt and Road Initiative.

The other satellite, the HEAD-4, was developed by Beijing-based HEAD Aerospace Technology Co. It can carry out on-orbit information collection from ships, aircraft and Internet of Things sensors.

Though the mission may have attracted a bit less attention than the SpaceX launch, it marked the 47th successful launch of the rocket, which was initially developed in 1992. It was also the 333rd flight of the Long March carrier rocket series.

More than one-third of the missions were conducted with rockets developed by the Shanghai academy, an arm of the China Aerospace Science and Technology Corp.

China used the Long March-1 rocket to launch its first satellite, Dongfanghong-1, into low Earth orbit in April 1970, becoming the fifth nation to achieve independent launch capability.

The Long March-2D, designed and built by the academy, is propelled by liquid propellants and has a liftoff thrust of 300 metric tons. It is capable of sending a 1.2-ton spacecraft into sun-synchronous orbit at an altitude of 700 kilometres.

The rocket is called the “golden rocket” and the “ever-victorious general” because it has sent 91 satellites into planned orbits without failure since its first mission in August 1992.

Engineers have continuously improved the rocket to increase reliability, according to Hong Gang, chief designer of the rocket.

“Before each mission, the design of the rocket is adjusted and improved according to the quality, interface and orbit of the satellites,” he said.

The rocket’s launch team of about 70 young engineers has also been well-trained, Hong said. Some three recruits are assigned to take part in each mission to gain experience and perpetuate the team’s solidarity and skills.

During the latest mission, the team managed to further shorten the launch process to 13 workdays from about 20 days previously.

To catch up on schedules delayed by the novel coronavirus outbreak, the first and second stages of the rocket, along with satellites and fairing structures that reduce drag, were transferred to the launch site within a day instead of the usual two.

The launch team has also devised bespoke maintenance plans for the launch site to make up for operations suspended during the COVID-19 outbreak. Every cable and block were inspected for the site’s first mission in 2020.

To maintain the rocket’s condition in the cold, windy desert conditions at the launch center, the team designed a special insulating layer to maintain humidity and temperature of the rockets. It drops off immediately after takeoff to reduce weight.

To expand the rocket’s commercial applications, designers have reserved enough space for multiple satellites to be launched together. The docking interface of the satellites has also been standardized and simplified.

“We used to mainly focus on the development and reliability of a carrier rocket, but now also consider its economic viability,” said Tan Xuejun, Chief Commander of the Rocket.

“That makes the rocket more competitive in the international commercial launch market.”

The rocket initially attracted attention from abroad in December 2012, after it sent a Turkish satellite into precise orbit. It then defeated rival rockets developed by Russia and Japan to win its first foreign bid.

Since then, the rocket has served clients from Venezuela, the Netherlands, Argentina, Ecuador, Denmark and Saudi Arabia.

In February, a Long March-2D rocket sent four new-technology experimental satellites into planned orbit from the Xichang Satellite Launch Center in southwest China’s Sichuan Province. The satellites are mainly used for the new Earth observation experiments.

In December 2018, the rocket sent six atmospheric environment research satellites and a test Communication Satellite into Orbit from Jiuquan.

“It was not an easy task to send the seven ‘passengers’ into the space simultaneously,” Tan said. “Those satellites belonged to five companies in three nations, with two separating methods and four interface types.”

Though the rocket has been developed for nearly three decades, Tan said it will continue to play a key role in China’s Long March rocket series.

Also on May 31, the Long March-11 carrier rocket, the newest member in the family, sent two satellites into orbit from the Xichang launch centre.

The Long March-11, developed by the China Academy of Launch Vehicle Technology, is the only rocket among China’s Long March series that uses solid propellants.

“It doesn’t mean the old models will be phased out soon,” Tan said. “The new rockets still need to accumulate experience and reliability through more missions. The old and new types of rockets will coexist for a period into the future.”

Author: Yang Jian