Long March 10

Long March 10, also known as the “Next Generation crewed launch vehicle” , and previously and unofficially as the “921 rocket” or the "Long March 5G" (a development of the Long March 5), is a Chinese super-heavy carrier rocket for crewed lunar missions that is currently under development. The nickname "921" refers to the founding date of China's human spaceflight program. In 2022, the first flight was targeted for 2027. By 2024, the first flight's target was moved up to 2025–26.In April 2024, it was announced that program development was complete.

The standard Long March 10 will be capable of lifting 70 tonnes into low Earth orbit (LEO) and 27 tonnes into trans-lunar injection trajectories.

There are also plans for a variant, the Long March 10A, which is designed primarily for future low Earth orbit crew and cargo transport to the Chinese Space Station. It will be partially reusable and capable of lifting at least 14 tonnes into LEO.

Overview
The Long March 10 is a human-rated super heavy launch vehicle designed to launch China's Mengzhou crewed lunar spacecraft and its future Lanyue crewed lunar lander, as part of its crewed space program, codenamed Project 921. Its notional debut was at the 12th China International Aviation & Aerospace Exhibition in November 2018, where it was announced that the China Academy of Launch Vehicle Technology (CALT) is developing a vehicle with a lunar orbit capacity of up to 30 tons, meeting the requirements for crewed lunar exploration. Documents and presentations in subsequent years depicted modified Long March 5 configurations known as CZ-5DY (pinyin abbreviation for 'Deng Yue' 登月 or lunar landing), CZ-5G, and CZ-5H.

In February 2023, at the "30 Years of China's Manned Spaceflight" exhibition held at the National Museum of China, a model of the next-generation crew launch vehicle was labeled as "Long March 10." An article later published by China Aerospace Science and Technology Corporation also used the term "Long March 10" to refer to the rocket.

Standard Configuration
The standard variant of the vehicle consists of two boosters, first, second and third stage cores, escape tower, and fairing. The first-stage core and the two boosters each have a diameter of 5.0 meters and are equipped with 7 YF-100K engines (for a total of 21 operational engines at liftoff). The second-stage core has a diameter of 5.0 meters and is equipped with 2 YF-100M engines. The third-stage core has a diameter of 5.0 meters and is equipped with 3 YF-75E engines. The vehicle's total length is approximately 90 meters, with a liftoff weight of 2,187 tons. The diameter of its core stage is the same as that of the Long March 5, but its height is about one-third taller.

The rocket has a payload capacity of 70 tonnes to low Earth orbit and at least 27 tonnes to a trans-lunar injection trajectory. The proposed crewed lunar mission would use two Long March 10s; the crewed spacecraft and the lunar landing stack would launch separately and subsequently rendezvous in lunar orbit, prior to a crewed lunar landing attempt. The development of the rocket along with relatively detailed specifications were announced at the 2020 China Space Conference.

Long March 10A variant
The Long March 10A is a single stick variant with only 2 stages; it has 7 YF-100K engines on the first stage and a single YF-100M engine on the second stage, This variant is designed for low Earth orbit crew and cargo flights; it is part of the Chinese space program's plan to increase lift capacity, explore reusability, and phase out hypergolic fuels for its carrier fleet. The 10A will have a capability to low Earth orbit of at least 14 tonnes when the first stage is recovered and at least 18 tonnes when used in a completely expendable arrangement; it will use kerosene as fuel and liquid oxygen as the oxidizer. The rocket's first stage will have restartable engines and grid fins to enable reuse after stage recovery. First stage landing and recovery will employ "tethered landing devices" in lieu of landing legs; this tethered system involves the deployment of "hooks" by the stage which would be caught by a tensioned wire system on the ground.

Precursor design
An old proposal from 1992 for China's "project 921" envisioned the adoption of a modular design for a new generation of human-rated launch vehicles that would allow various payload combinations ranging from 11 tons to 70 tons to low Earth orbit. One such combination would have allowed China to pursue its own crewed lunar exploration program, including lunar orbit, circumlunar, and lunar landing missions. This proposal was not adopted. However, elements of this old proposal appear to have survived in the current Long March 10 designs.

Proposal and development



 * 2017
 * China Aerospace Science and Technology Corporation (CASC) initiated preliminary research on the next-generation crew launch vehicle.
 * CASC completes the first test run of the first-stage engine, YF-100K.
 * 2018
 * Jun–Jul, CASC completes three test-runs of the second stage engine, YF-100M
 * Nov, a model of the next-generation crew launch vehicle made its first appearance at the 12th Zhuhai Airshow.
 * 2019
 * Sep, CASC announced the successful development of the first 5-meter diameter conical bottom structure storage tank, achieving a 15% weight reduction.
 * Oct, a project named "5-meter Diameter Module of the Next-Generation Crew Launch Vehicle – Overall Technology and Engineering Application" successfully passed the acceptance review organized by the CMSA.
 * Nov, CASC announced the successful development of a 5-meter liquid oxygen-kerosene storage tank.
 * 2020
 * Oct, full-scale structural prototype of the thrust transfer structure, which parallel-mounts seven new liquid oxygen-kerosene engines on the first stage had been manufactured and completed static load testing.
 * 2022
 * Jun 14, CASC conducts the first long-duration ignition test of the third-stage engine, YF-75E.
 * July 28, CASC conducts static and dynamic test of multiple engines in parallel
 * July 29, CASC conducts high-altitude, high-thrust long-duration test of the YF-75E third-stage engine.
 * Sep–Oct, CASC completes three test runs (650 seconds in total) of the second-stage engine, YF-100M, using a large-sized titanium alloy nozzle extension concept. The engine passed the 105% high-altitude and high mixture ratio assessments and met the overall requirements.
 * Oct, CASC announced that the cumulative test duration of the YF-75E third-stage engine had exceeded 10,000 seconds.
 * Nov 26, CASC completes the first two ignition test runs of the YF-100K first-stage engine, achieving breakthroughs in key technologies such as high-pressure staged combustion with two ignitions, low-pressure start-up, and continuous thrust variation for reusable engines
 * Nov–Dec, CASC conducted four consecutive test runs (a total of 2,100 seconds) of the YF-100K first-stage engine, with each engine working more than 8 times the mission duration.
 * 2023
 * Feb 24, an exhibition held at the National Museum of China showed the next-generation crew launch vehicle was officially named "Long March 10".
 * March 29, the first eight-piece accumulator successfully passed the cryogenic shock and 1.4 MPa pressure tests. This component is used in the core stage's oxygen delivery system for the Long March 10.
 * May 19, CASC successfully completes grid fin deployment test for the next-generation crew launch vehicle. This test, conducted at the conceptual verification stage, verified the correctness of the grid fin design. The grid fin is an aerodynamic control mechanism for rockets, often referred to as the "small wings" of the rocket. When deployed, it helps maintain the rocket's stability during descent and enables precise landing of the booster stage.
 * May 28, CASC conducted the sixth test run of the YF-100K first-stage engine, with a cumulative test duration of 3,300 seconds, setting a new record for single-engine testing of a Chinese engine in the hundred-ton class.
 * May 29, CMSA commences the lunar landing phase (Phase 4) of the Chinese Lunar Exploration Program, with the Long March 10 being developed as the main vehicle for the program.
 * June 12, CASC completed the eighth test run of the YF-100K first-stage engine, with a cumulative test duration of 4,400 seconds, once again breaking the record for single-engine testing of a Chinese rocket engine in the hundred-ton class.
 * 2024
 * April 24, Lin Xiqiang, deputy director of China Manned Space Agency (CMSA), stated that the development of various articles necessary for China's lunar missions such as the Long March 10 carrier rocket have been completed; he added that mechanical and thermal products for the Mengzhou, Lanyue, and possibly for the carrier rocket as well have also been completed and that the needed rocket engines are undergoing hot fire tests. Furthermore, the crewed lunar exploration launch site for the Long March 10 is currently under construction near the existing coastal Wenchang spaceport in Hainan province.
 * June 14, A successful test on Long March 10's sub-level propulsion system was conducted, marking the first large-scale ground test at a system wide level. During the test, three YF-100K first-stage engines started as expected, operated stably, and shut down on time, with all parameters testing normal; the three engines generated a combined thrust of 382 tonnes for several minutes. Compatibility between the sub-level boost delivery system and the engine, the propellant refueling process, the multi-engine parallel transmission of force, and environmental characteristics were fully verified through technical testing, the China Academy of Launch Vehicle Technology (CALT) reported. Simultaneously, construction activities on Long March 10's launch facilities at Wenchang Satellite Launch Center were confirmed to be underway by satellite imagery.