After the second launch of the "Starship" rocket, there was an explosion after the first-stage separation and the second-stage loss of contact. The US manned moon landing program was highly unlikely to send people to the moon as planned.
The second launch of Starship was originally scheduled for November 17th, but the launch time was postponed to 18th due to a problem with a grille rudder of the rocket, which required replacement of the driver. As the largest rocket of mankind at present, the second launch of Starship still attracts the attention of the whole world. Although it did not fully achieve the expected goal, the flight time was longer, and the first and second stages were successfully separated. Compared with the first flight, there were more technical progress and achievements.
A somewhat different "starship"
In April this year, "Starship" ushered in its first flight test, but after liftoff, it was found that many engines in the first stage were not working normally. After liftoff for 2 minutes and 30 seconds, the attitude of the rocket became unstable and began to rotate, and finally it disintegrated and exploded, and the launch failed.
Later, SpaceX announced the cause of the failure, saying that after the launch of the "Starship", several engines failed, lost altitude and began to rotate, and issued instructions to the spacecraft to terminate the flight. SpaceX said that the "Starship" has set up a self-destruction mechanism in the event of an accident to prevent the rocket from falling freely and threatening the safety of human beings on the ground.
It is said that the engine failed because the leaked propellant at the back end of the overweight booster caught fire and finally cut off the connection with the main flight computer. This led to the loss of signal of most booster engines, and eventually led to the interruption of the "Starship" control system.
Afterwards, SpaceX implemented leakage mitigation measures and improved the testing of engine and booster hardware. In addition, SpaceX upgraded the existing fire extinguishing system of overweight booster to reduce the risk of engine fire in the future.
Starship is a heavy-duty launch vehicle developed by SpaceX, which adopts reusable design. The rocket consists of two parts: the take-off stage is called "Super Heavy Booster", and 33 Raptor liquid oxygen methane engines are installed in parallel, of which 13 are built in to change the thrust direction, with a maximum thrust of about 7,600 tons; The second stage is actually a spaceship with six engines (including three vacuum Raptor engines and three sea-level Raptor engines). The maximum carrying capacity of Starship in low earth orbit is 250 tons, and it is 150 tons in recoverable state.
Get up from where you fell. In response to the failure of the first flight, Musk said in September that SpaceX has made more than 1,000 modifications to the Starship since its first flight in April. The most important change is the interstage thermal separation method, that is, the second-stage spacecraft of the Starship ignites the engine when it has not been separated from the first-stage overweight booster. Musk said, "Thermal separation has the advantage of loading into orbit, and conservatively speaking, the carrying capacity has increased by about 10%."
Musk said that when the engine of the "Starship" second-stage spacecraft was ignited, a few engines of the overweight booster were still working. This can prevent the vehicle from losing thrust in the traditional stage separation process when the first stage engine is turned off first.
In order to improve the carrying capacity, most rockets adopt multi-stage design. Separation between rockets is one of the key technologies of launch vehicles, and whether it can be successfully separated directly affects the success or failure of the mission. At present, there are two separation forms of interstage separation: cold separation and thermal separation. Thermal separation means that the rocket at the back stage is pushed away by the high-temperature gas jet from the rocket engine at the front stage, and the engine at the front stage is already ignited when the connector is unlocked; The cold separation uses the separation energy installed on the separation body to provide separation energy, and the engine of the first stage rocket will not ignite until the first and second stages of rockets are separated.
The two separation methods have their own advantages and disadvantages. The thermal separation method does not need to accelerate the engine twice, which reduces the dead weight problem and improves the carrying capacity to some extent. But there are also some problems in thermal separation, which need to be paid attention to when using this technology. For example, the "Starship" stage will be directly hit by the flame during thermal separation, and the time must be controlled well, otherwise it may affect the reuse of the arrow body. Secondly, thermal separation is fast, and if there are design problems or unexpected factors, it may lead to accidental damage of the rocket.
Judging from the live video of this launch, the thermal separation technology was successful, and all 33 engines in the first stage were ignited, but it exploded shortly after thermal separation. The second stage was about to run out of time machine when the propellant was about to run out, and then the telemetry signal was lost. Although the second launch did not meet expectations, it took longer than the first flight, which verified more technologies.
The United States may not be able to send a man to the moon on time.
The second launch of Starship failed to fully meet expectations. Although this is an acceptable setback under SpaceX’s "rapid iteration" and "flying instead of testing" rocket development mode, these setbacks are likely to drag down the US manned moon landing plan and its own company’s space program.
In August this year, NASA officials said that if the research and development progress of key systems can’t keep up, the "Al themis 3" manned moon landing program may not include the astronauts’ landing on the moon. Jim Fry, an official of NASA’s Exploration System Development Task Department, told the media that if key equipment such as the manned lunar landing system developed by SpaceX (that is, the moon landing version of "Starship") is not in place in time, "we may finally perform it once (with the plan). Different tasks."
NASA Director Bill Carney once said, I ask such a question every day: How is SpaceX progressing? All the managers told me that they were achieving all the milestones.
In 2019, the U.S. government announced the new moon landing plan of "Al themis", and has completed the mission of "Al themis 1" orbiting the moon. NASA plans to carry out the manned mission of "Al themis 2" around the moon in November next year.
In the American moon landing plan, SLS rocket+Orion spacecraft+moon landing version of "Starship" are the three most critical parts, which are indispensable. Although the development progress of the first two is protracted and costly, the research and development have been completed, and everything went well for the first test flight. According to the plan, only one manned test flight around the moon needs to be completed in 2024, and the conditions for landing on the moon are met.
In the new moon landing plan of Al themis, the moon landing version of "Starship" will carry astronauts away from the "portal" lunar space station to carry out the moon landing mission. After landing on the lunar surface to complete the mission, the "Starship" took off again to dock with the lunar portal, sent the astronauts to the "portal" space station, and returned to Earth after a rest in the "Orion" spacecraft. After the second launch, "Starship" will have to carry out many verification flights, including a series of major test challenges, such as recovery of launch pad, rapid reuse launch, on-orbit refueling, unmanned lunar landing demonstration, etc. It is said that it may take at least ten flight tests and success before it can meet the conditions for landing on the moon. Now, the "Starship" has become the X factor for the United States to return to the moon in 2026.
It is worth mentioning that one month after the first flight of Starship failed, on May 19th, NASA announced that it had signed an additional contract with Blue Origin Company to develop a second manned lunar lander, which will make its first manned flight as part of the mission of Al themis 5. Blue Origin’s lunar lander is smaller than the moon landing version of Starship, with a payload of only 20 tons. The lander uses a combination of liquid hydrogen and liquid oxygen propellant as fuel, and plans to carry out its fifth mission in 2029. Some analysts believe that because NASA saw the progress of the Starship delayed and there were some technical uncertainties, it decided to choose a "spare tire" for the moon landing version of the Starship, and the blue origin company’s plan was "spare tire".
William Gersten Mayer, vice president of SpaceX in charge of construction and flight reliability and a former senior employee of NASA, once said that if the delay continues, eventually, we will lose our leading position and we will see China land on the moon before us.
In July this year, the China Manned Space Engineering Office issued the "Announcement on Collecting the Scientific Load Plan for the Manned Lunar Exploration Project", pointing out that the mission of the manned lunar exploration project in China has been launched, and it is planned to carry out unmanned lunar landing in advance and realize the first landing of China people on the moon by 2030.
China’s initial plan for manned landing on the moon is to use two launch vehicles to send the lunar lander and manned spacecraft to the Earth-Moon transfer orbit respectively, and the spacecraft and lander will rendezvous and dock in the orbit around the moon, and the astronauts will enter the lunar lander from the spacecraft. After that, the lunar lander will descend and land in the predetermined area of the lunar surface, and the astronauts will land on the moon to carry out scientific investigation and sample collection. After completing the established mission, the astronauts will ascend to orbit around the moon on the lander and rendezvous and dock with the spacecraft, and return to Earth on the spacecraft with samples.
It is reported that China has fully deployed and carried out various research and construction work, and researchers are developing the Long March 10 carrier rocket, a new generation of manned spacecraft, a lunar lander, a lunar landing suit, a manned lunar rover and other equipment. The take-off weight of the Long March 10 is about 2,187 tons, the take-off thrust is about 2,678 tons, and the carrying capacity of the Earth-Moon transfer orbit is not less than 27 tons. It is expected that it will have the first flight conditions in 2027, and the new generation manned spacecraft test ship will successfully make its first flight in May 2020. The lunar lander under study weighs about 26 tons and consists of a lunar module and a propulsion module. It can deliver two astronauts to the lunar surface and is mainly responsible for lowering the astronauts from the orbit around the moon to land on the lunar surface and returning to the orbit around the moon. At the same time, the lunar lander also has the ability of autonomous control flight.
The United States was once the first country in the world to successfully land a man on the moon. It hopes to win the top spot again in the lunar exploration boom in the new century, and now the pressure is coming.
