China this month succeeded in using landing legs to set a first-stage rocket booster down vertically on land. It follows last month's feat of catching a booster with a net at sea. With China unveiling different recovery methods one after another after U.S. SpaceX, the race for reusable launch vehicles is accelerating.
Zhuque-3 Yao-2, developed by Chinese private space company LandSpace, lifted off on the 19th and placed its second stage into the planned orbit. The separated first-stage booster then returned to the launch site and landed vertically with landing legs deployed under the fuselage. It was the first time China recovered a reusable first stage on land using this method.
Park Chang-su, Director General of the Korea Aerospace Research Institute (KARI) Next-Generation Launch Vehicle Program, said, "In that it succeeded in first-stage recovery, you can see it as having passed the first step toward reuse," and added, "Judging by the landing technology itself, it has secured technology almost identical to SpaceX's Falcon 9."
◇ Light rocket vs. simple facilities… different trade-offs by recovery method
The key to a reusable rocket is recovering the costly first-stage booster. China's Zhuque-3 this time used a method in which the rocket stands directly on its legs. As the booster returns to the ground, it reignites its engine to slow down and deploys legs under the fuselage just before touchdown. SpaceX's Falcon 9 also uses this method.
The advantage of the legs-first method is that it does not require complex capture facilities on the ground. On the other hand, because the rocket must carry landing legs and supporting structures, the launch vehicle becomes heavier and, as a result, must carry fewer satellites or payload by the amount of added weight.
Ahn Jae-myung, a professor of aerospace engineering at KAIST, said, "With the landing-leg method, the legs bear large loads, so the structure must be well designed, and the launch vehicle's weight increases by the weight of the legs," adding, "Instead, on the receiving side, you only need to prepare the landing ground well, so operational burden is relatively low."
The "net capture method" China showcased in last month's Long March-10B test shifts the weight burden outside the rocket. When the booster descends over a sea platform, large cables and a net-like structure catch it.
Park, the Director General, said, "By eliminating the landing legs, you can make the rocket lighter and carry that much more satellites or cargo," adding, "There is also the advantage that the net can move and absorb certain position errors. Instead, you must install and operate a large capture structure at sea."
SpaceX Starship's so-called "chopsticks" method starts from the same idea. When the first-stage Super Heavy booster returns to the launch site, giant mechanical arms installed on both sides of the launch tower grab the booster in midair like chopsticks. Separate landing legs are not needed, but the booster, which is tens of meters tall, must be brought very precisely to a fixed position on the launch tower.
Asked which of the three methods is the hardest, Park, the Director General, picked the Starship method. Park explained, "With the Starship method, a large structure must catch the booster after it arrives exactly at a fixed position, so the technical difficulty is quite high."
Park added, "In the long term, sending the launch vehicle straight back to the original launch site is advantageous in terms of expense and launch cadence," noting, "If you recover at sea, you have to move the rocket back to land and you can also be affected by weather."
◇ China begins chasing SpaceX… Korea is only now at the demonstration stage
Professor Ahn said China's latest success is meaningful progress, but it is too soon to say it has caught up with SpaceX. For reusable launch vehicles, the goal is not just to safely catch a rocket once; you must inspect the recovered booster, relaunch it, and repeat the process multiple times to prove safety and economics. SpaceX has already built experience over years by repeatedly recovering Falcon 9 first stages and launching them again.
Professor Ahn said, "SpaceX began succeeding in reusable launch vehicle recovery roughly 10 years ago, in 2015," adding, "China is only now starting to build reliability in reusable technology, and succeeding once in recovery and performing it repeatedly without mistakes are worlds apart." However, unlike SpaceX, which pioneered the path, China already has other success cases to reference, so the chase could proceed faster.
Meanwhile, Korea is pursuing development of reusable launch vehicle technology but is still in the early stages. Park, the Director General, said, "We are currently developing a scaled-down demonstrator and preparing for flight tests," adding, "Around 2033, we will begin testing the main launch vehicle, and by 2035 we aim to secure reusable technology."
Professor Ahn stressed that for Korea, it is more important to first improve the launch vehicle's own performance than to develop landing gear. To bring a rocket back, you must carry additional fuel and equipment for return, so you need sufficient performance margin from the start.
Ahn said, "To use it as a reusable launch vehicle, it must be a high-performance launcher from the outset," adding, "Efforts to reduce launch vehicle weight and improve engine performance—basic improvements to launch vehicle performance—must come first."