China is developing a parachute system to help control where its rocket boosters land instead of free-falling onto the ground near populated areas.
The China Aerospace Science and Technology Corporation (CASC) is finalising a plan whereby it uses a parachute and a gliding control system on some of its Long March rockets’ boosters and payload fairings, CCTV reported (English translation provided in the video). The parachute will significantly narrow down the falling booster’s landing area from 90 kilometres to 30 kilometres.
With this plan, China could also reuse the boosters for future launches. “We’ll also make the landing area into a landing bed by adding cushion, making it soft as a mattress,” Teng Haishan, deputy chief engineer of the No. 508 Institute of China Academy of Space Technology (CAST), told CCTV. “As a result, the booster will be completely recyclable without any damage.”
The parachute system is designed to be installed on the side boosters of China’s Long March 3B, 3C and 2F rockets. As Jonathan McDowell, an astronomer at the Harvard-Smithsonian Centre for Astrophysics, pointed out, the rocket’s side boosters don’t really go to space — they just barely make it up to 50 kilometres above the surface. “This is more about controlling where they land so that they don’t smash into villages,” he told Gizmodo over the phone. “If you can decrease the uncertainty of where these things are going to land, you can have a reasonable sized evacuation area.”
However, China still has a bigger falling rocket problem with its Long March 5B (which weighs a whopping 21.6 tonnes), which would require a more intricate solution. In November 2022, a Long March 5B core stage fell uncontrollably towards Earth, breaking up over the eastern Pacific Ocean, with debris falling to the southwest of the Mexican coast. During its unpredictable descent, Spain was forced to shut down its airspace.
That was the fourth incident involving an uncontrolled Long March 5B core stage. Two years ago, debris from the inaugural launch of the rocket fell onto the Ivory Coast, causing damage to people’s property. For the rocket’s second flight, the booster fell into the Indian Ocean away from populated areas. And on its third flight in July 2022, it reentered Earth’s atmosphere, with pieces of space junk crashing down onto parts of Indonesia and Philippines.
The Long March 5’s booster does go into orbit to deliver its payload. “Before you even get to the point of having to worry about parachutes, you’ve got to get them out of orbit,” McDowell said. “The rocket stages transmit data for maybe another 10 minutes or something and then they’re dead pieces of metal in orbit, going around and around the Earth until they eventually re-enter weeks later.” So if it would have a parachute on it, it would fly but there’s still no real way to control where it lands.
The solution, McDowell said, is to not let the boosters get to that point. Instead, he suggests that the rocket stage itself doesn’t deliver the payload to orbit, but rather a separate, smaller engine give the payload that final push to its designated spot while the stage falls back to Earth before ever getting into orbit. However, that adds more cost, and risk, to the mission, which is why China may have steered clear from it.
Another way is to perform a controlled reentry by using an engine burn that would steer the rocket towards a remote area, where it can fall freely to the ground without posing a risk to people. Again, that requires extra fuel and a design upgrade that adds more cost.
It’s not just China’s problem, it’s an industry problem as a whole. About 60% of launches to low Earth orbit in 2020 resulted in a rocket body being left in orbit, recent research showed. The study predicted a 10% chance of one or more casualties from falling rocket debris in the next decade.
McDowell is part of a group of experts who recently drafted the Montreal Recommendations on Aviation Safety and Uncontrolled Space Object Reentries, a declaration that calls for preventing uncontrolled reentries.
China taking a small step towards strapping some of its side boosters to parachutes in order to control their re-entry is a start. “China’s attitude to risk is, I think, slowly maturing, or slowly getting more in line with other countries,” McDowell said. “This is another sort of example where they were being cavalier before, and now they’re being a little more careful.”
“It’s good for the people who live within range from Xichang [spaceport], and it’s also good more broadly as a sign that China is developing a more safety conscious culture,” he added.
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