Tech to help tame descent of rockets

Watching a giant rocket blast off and roar heavenward is an unforgettable experience for most people. But for those located far from the launchpad and under the path of trajectory, rockets are a source of concern as debris might fall to the ground.

Chinese engineers have begun developing a technology that will help minimize hazards for those below a carrier rocket's trajectory and also enable rockets to be reused, according to project leaders at the China Academy of Launch Vehicle Technology, the country's major carrier rocket maker.

During China's latest rocket launch on Friday from Xichang Satellite Launch Center in Sichuan province, researchers from the academy conducted the country's first successful controlled-descent test of a major part of the rocket, He Wei, a senior rocket scientist, said on Sunday.

They installed a set of devices known as grid fins－foldable, adjustable heat-resistant wings－between the first and second stage of a Long March 2C liquid-propelled carrier rocket.

After the 23-meter-tall first stage burned up its fuel and separated from the second stage, the grid fins were unfolded and began to steer the first stage as it fell back from the edge of space through the Earth's atmosphere, He said.

The scientist said that thanks to the grid fins, debris from the first stage returned to a designated area in Guizhou province, adding that the test showed that China has become the second nation after the United States to possess controlled-descent technology for carrier rockets.

Cui Zhaoyun, deputy chief designer of the Long March 2C, said Friday's test was a challenge for researchers of the grid fin because compared with small rockets, it is more difficult to fulfill controlled reentry of large models like the Long March 2C.

Xing Qiang, founder of Micro-Rocket Union, a nonprofit space research organization in Beijing, said that grid fin technology has been widely adopted on carrier rockets and weapons such as ballistic missiles for a long time. But before Friday's test, it had only been used by the US' SpaceX for controlled descents.

SpaceX engineers use grid fins, together with other apparatus, to make their Falcon 9 series rockets reusable.

"Compared with traditional fins on rockets, grid fins feature better aerodynamic efficiency and allow the rocket's debris to conduct controlled descents," he said. "The type used by the Long March 2C rockets is very difficult to design and is a true test of designers' know-how in aerodynamics and rocket structure."

As China has become one of the biggest users of carrier rockets, finding solutions to the safety hazards caused by an uncontrolled fall of rocket debris is being prioritized on researchers' agendas.

Currently, people in potential rocket debris areas are evacuated to safe places during each launch mission.