SpaceX's "Starship" was successfully tested for the fourth time, where is the ga

SpaceX's Starship completes its fourth test flight, meeting its objectives, and the heavy-lift rocket once again becomes the focus of global attention.

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Successful Fourth Test Flight of SpaceX's Starship

At 20:50 last night, SpaceX's Starship successfully launched from its base in Texas, USA, marking its fourth flight test.

Live footage showed that one of the engines failed to ignite normally during the launch, but thanks to the redundancy of three engines designed into the Starship, it still maintained normal flight.

Subsequently, the Starship separated from the booster as planned. Seven minutes after liftoff, the Super Heavy booster splashed down in the Gulf of Mexico, and SpaceX CEO Elon Musk announced the successful soft landing of the Starship booster. Meanwhile, the second stage of the rocket continued to fly in space. The live broadcast displayed "waiting for signal identification" for a long period after 12 minutes.

Nearly 40 minutes after the launch, the live broadcast signal resumed, and the Starship re-entered the atmosphere. During the flight, some parts of the Starship and the live broadcast camera were severely damaged due to high temperatures. Subsequently, it was observed that the altitude of the Starship continued to decrease, and it ultimately splashed down in the Indian Ocean.

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Last night's test flight was the first time in the history of SpaceX's super rocket "Starship" that all missions were completed. SpaceX founder Musk announced that the "Starship" successfully made a soft landing in the ocean, congratulating the SpaceX team on their tremendous achievement.In Musk's vision, the "Starship" is the vehicle that will take humans to Mars, which is also the core goal of his founding of SpaceX. Thanks to its rapid development momentum, SpaceX's valuation is soaring. At the end of May this year, media reports cited sources as saying that Musk's SpaceX has begun discussing the sale of existing shares, with the company's valuation potentially reaching 200 billion US dollars (approximately 145 billion yuan).

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Breakthroughs in Heavy-Lift Launch Vehicles

Starship is the largest and most powerful launch vehicle in the world to date. According to SpaceX, the Starship is equipped with multiple "Raptor" engines, with a total height of about 120 meters and a diameter of about 9 meters. The rocket consists of two parts: the first stage booster "Superheavy" and the second stage spacecraft "Starship."

The successful launch of Starship holds revolutionary significance for the history of human spaceflight, as it is capable of delivering over 100 tons of cargo into orbit in one go. Starship is also a fully reusable rocket, which will significantly reduce the cost of space activities and help Musk achieve his "Mars dream."

As planned, Starship can perform long-term flight missions between Earth and the Moon, and also serve as a cargo ship and manned spacecraft for Mars missions. The rocket is planned to replace most of the Falcon 9, Falcon Heavy launch vehicles, and Dragon spacecraft missions.

In fact, in recent years, with the rise of the lunar exploration boom, heavy-lift rockets necessary for manned lunar landings and deep space exploration have been receiving increasing attention.

Heavy-lift launch vehicles refer to rockets capable of launching satellites and manned spacecraft of different types into low, medium, and high Earth orbits. According to Baidu Baike, the takeoff thrust of a heavy rocket reaches 3,500 tons, with a low Earth orbit payload capacity of 100 tons; geostationary orbit payload capacity of 18 tons; lunar orbit payload capacity of 32 tons; and Martian and Venusian orbit payload capacity of 28 tons.Internationally, the definition of heavy-lift launch vehicles varies. For instance, according to the definition on the NASA website, heavy-lift launch vehicles typically refer to rockets with a large payload capacity, such as the Saturn V rocket, which can deliver over 100 tons of payload into low Earth orbit. Additionally, Wu Yanhua, the deputy director of the China National Space Administration, mentioned that China's heavy-lift launch vehicles are in the stage of deepening research and development, as well as key technology breakthroughs, with a low Earth orbit capability ranging from 50 to 150 tons.

China is developing a heavy-lift launch vehicle with a diameter of 10.6 meters and a height of approximately 110 meters, capable of carrying over 150 tons to low Earth orbit. This indicates that China's heavy-lift launch vehicles are designed on a large scale with significant payload capacity.

Following the successful launch of China's Long March 5 series of large launch vehicles, there has been considerable international interest in "China's heavy rocket project for deep space exploration." The Long March launch vehicle program began in the 1960s, with the capability to launch satellites of various types and manned spacecraft into low, medium, and high Earth orbits, as well as unmanned deep space exploration capabilities. The low Earth orbit (LEO) payload capacity reaches 25 tons, the sun-synchronous orbit (SSO) payload capacity reaches 15 tons, and the geostationary transfer orbit (GTO) payload capacity reaches 14 tons, with a launch success rate of 96.7% for Long March rockets.

The "Space" website in the United States stated that the most powerful rocket in China's current low Earth orbit payload capacity is the Long March 5 series, with a payload capacity of 25 tons. Reports suggest that since 2018, China has proposed the Long March 9 heavy rocket with a low Earth orbit payload capacity of up to 140 tons, expected to make its maiden flight around 2028. Foreign media also speculate that the core stage of the Long March 9 heavy rocket will have a diameter of 10 meters, a height exceeding 103 meters, and a liftoff thrust of over 4,000 tons. Additionally, it will adopt reusable rocket technology to reduce launch costs. The Long March 9 heavy-lift launch vehicle is expected to achieve its first flight around 2030.

Currently, there are four common heavy-lift launch vehicles in service internationally:

- The "Delta IV" rocket — a product of the U.S. low-cost rocket research program at the beginning of this century, it is a medium large-thrust rocket with a low Earth orbit payload capacity of 11 to 25 tons. The first stage uses liquid hydrogen and liquid oxygen as fuel. Launched at the beginning of this century, this rocket became popular due to its low cost and reliable performance.

- The "Atlas V" rocket — produced by the United Launch Alliance, it has a low Earth orbit payload capacity of about 19 tons and a geostationary transfer orbit payload capacity of about 9 tons. Due to the use of Russian-made engines, the U.S. Congress has legislated a ban on the future use of the "Atlas V" rocket by U.S. agencies, which is also the reason for the company's development of the "Vulcan" rocket.

- The "Ariane 5" rocket — a large-thrust launch vehicle produced in Europe, with its first test launch in 1996 and commercial launches starting in 1999. The rocket can deliver 20 tons of payload to low Earth orbit and 10 tons of payload to geostationary transfer orbit.

- The "Angara 5" rocket — a large launch vehicle from Russia, with its first successful launch in 2014. The rocket has a low Earth orbit payload capacity of nearly 25 tons and a geostationary transfer orbit payload capacity of over 7 tons.The Future Development Trends of Launch Vehicles

Launch capability is the most important parameter of a launch vehicle, referring to the maximum mass of payload that the rocket can carry to a certain orbit, characterizing the sum of kinetic and potential energy that the rocket can provide to the payload.

There are significant differences between Chinese and American launch vehicles in terms of technology, thrust, and application.

In terms of thrust and launch capability, American launch vehicles have historically reached very high levels. For example, the "Saturn V" rocket used in the 1969 Apollo moon landing mission had a thrust of 3,408 tons, with a launch capability of 45 tons to lunar orbit and 118 tons to low Earth orbit, making it the largest rocket in the world to date. In addition, America's SLS (Space Launch System) rocket is considered one of the most powerful launch vehicles globally, with a low Earth orbit payload capacity of 70 tons and a translunar transfer orbit capacity of 27 tons.

In comparison, although China's Long March series of rockets also has strong launch capabilities, there is still a gap in maximum thrust and launch capabilities. For instance, the Long March-5B rocket has a low Earth orbit launch capability of 22 tons, while the Long March-9 rocket is expected to reach a thrust of 4,000 tons, which will make it the most powerful launch vehicle in China to date.

In the field of commercial launch vehicles, SpaceX in the United States is leading in terms of launch frequency and technological innovation. In 2018, there were a total of 29 rocket launches in the United States, with SpaceX accounting for 70% of them. SpaceX's "Starship" rocket is a new generation of reusable heavy-lift launch vehicle, with an overall length of about 120 meters and a diameter of about 9 meters, consisting of two parts: the first stage is the "Super Heavy" booster, about 70 meters long, and the second stage is the reusable "Starship" body, about 50 meters long.

China's commercial launch vehicle market is also developing rapidly, but it still faces challenges in terms of cost and recycling. Although China's Long March series of rockets has surpassed the United States in the number of launches, it still needs to improve in terms of competitiveness and cost-effectiveness.Currently, there is an issue with insufficient payload capacity in China's rockets. The Long March 5 rocket, which has the largest payload capacity in the country (with a near-earth orbit payload of 25 tons), is outperformed by the Falcon Heavy rocket, which has a payload capacity of 63.8 tons. The payload capacity of China's private rockets is relatively weak, indicating a significant room for improvement for private rocket companies in the future.

In terms of launch costs, China's carrier rockets still have a considerable gap compared to advanced medium to large liquid carrier rockets from abroad. According to the analysis in "Analysis and Enlightenment of Domestic and International Carrier Rocket Launch Service Prices," the low-orbit launch costs for SpaceX's Falcon 9H and Falcon 9 are 0.95 and 1.8 thousand USD/kg, respectively. There is also room for price increases in the launch services of Russian and European rockets. China's future rocket launches are also continuously developing in the direction of increasing the number of reuse times and reducing launch costs.

At present, China has built four major space launch centers: Jiuquan, Taiyuan, Xichang, and Wenchang. Each is strategically located and has its own characteristics, jointly supporting China's space launch missions. By the end of 2023, Hainan Wenchang will see the completion of China's first commercial space launch center—the Hainan International Commercial Space Launch Center. It is planned to achieve regular launches by 2024 and will become China's fifth space launch center, further enhancing the launch capabilities of China's civil and commercial carrier rockets.

The Hainan International Commercial Space Launch Center is designed with two workstations, planned for 16 launches per year. Workstation 1 is for launching the Long March 8 rocket, and Workstation 2 is for launching more than a dozen types of rockets from nine manufacturers.

Achieving the reuse of carrier rockets is an important measure to reduce costs and will become one of the core characteristics of the next generation of carrier rockets. Taking the Falcon 9 as an example, as the number of reuse times increases, the launch cost gradually decreases and tends to flatten. After 18 reuses, the launch cost is close to one-third of the cost of a single-use carrier rocket.

Currently, there are three methods for recovering the rocket body: parachute recovery, vertical return, and winged flyback. Each recovery method has its own characteristics, and the choice of which method to use should be based on the technical and developmental situation of one's own carrier rocket, as well as the mission requirements, to make the most suitable choice.Represented by the Chinese private rocket company Blue Arrow Aerospace, the launch cost of the Zhuque-2 rocket is also continuously being optimized and improved, with the potential to catch up with and surpass the world's advanced level in the future.