Starships keep exploding and iterating
2023-11-20
On April 20 this year, the Starship rocket was launched from the Star Port. It is more than 120 meters long and consists of two parts. The lower stage is the super heavy propeller , and the upper stage is the spaceship, which is the starship. The rocket initially climbed all the way up to an altitude of about 39 kilometers, with a top speed of more than 2,000 kilometers per hour.
But that day, and about 3 minutes after launch, the super-heavy thruster did not separate from the spacecraft as expected, and the two continued to be connected together. The aircraft experienced a series of engine failures, dropped in altitude, and rolled in the air... In the end, the starship was destroyed by an explosion 4 minutes after liftoff. It did not enter the Earth's orbit as planned, and the test ended prematurely.
According to the situation described by SpaceX, during the first orbital flight test, leaking propellant from the Super Heavy thruster caught fire, disrupting communication between the thruster and the main computer, causing most of the engines on the thruster to lose control. After the Starship rocket began to roll, the Autonomous Flight Safety System (AFSS) issued a destruction command, but this command did not take effect immediately. Instead, it was unexpectedly delayed for 40 seconds before the spacecraft exploded.
In addition, some facilities at the launch site were damaged during the first orbital test. As the rocket lifted off, the engines on the thrusters blasted a crater out of the launch pad, sending chunks of cement and other debris flying into the surrounding infrastructure.
In response to various problems with the last test launch, SpaceX stated in September this year that it had implemented measures to mitigate leaks, improved hardware testing of engines and thrusters, and improved the reliability of the Autonomous Flight Safety System (AFSS). In addition, SpaceX has also made improvements to the launch pad, including strengthening the launch tower, adding water sprinklers, etc.
In fact, long before it entered orbital testing, the starship prototype had been continuously blown up in various tests, including of course the first orbital test in April this year. SpaceX will analyze the data after each explosion, iterate the equipment, and prepare for the next test.
On February 28, 2020, the Starship prototype numbered SN1 exploded during a pressure test. The test tests the fuel tank's ability to hold extremely cold liquid under high pressure - a critical capability since the Starship's Raptor engines use a combination of liquid methane and liquid oxygen propellants. Engineers injected super-cold liquid nitrogen into the fuel tank. As the pressure increased, the fuel tank burst and the spacecraft disintegrated.
Although the experimental results were unsatisfactory, the team also found that the rupture of the fuel tank occurred near the thrust puck. Therefore, they made the structure of the disc the focus of the next test, and the modified next-generation prototype SN2 passed the pressure test on March 8 of that year.
On May 29, 2020, the Starship prototype SN4 exploded after a static ignition test of the engine, causing a fire. Musk said a fuel leak caused the explosion, and the next prototype will fix the problem. However, SN4 had passed four ignition tests before this and became the longest surviving starship prototype at the time.
After several spacecraft exploded, SpaceX even began to deliberately create explosions. For example, on June 23, 2020, the prototype numbered SN7 exploded again during a pressure test. Different from the past, this time the scientists were testing the limits of the fuel tank and deliberately caused an explosion, with white nitrogen clouds spurting out. During this period, the team wanted to replace the 301 stainless steel used in manufacturing the hull with 304L. The experimental results indeed confirmed that 304L has better performance than 301.
Later, during flight tests, the prototypes experienced more violent explosions.
On December 9, 2020, the Starship prototype SN8 conducted an impressive high-altitude test flight. It reached a maximum altitude of 12.5 kilometers above the ground. At that time, it shut down the engine, laid itself down, and prepared to glide to the launch pad and land vertically. But during an attempted vertical landing, insufficient pressure in the fuel tanks caused a hard landing and the prototype exploded. But Musk is still excited: "Just flying to the highest point is already very strong, and being able to land at the exact location is even more epic."
On February 2, 2021, SN9 also exploded due to a violent impact during landing. On March 7, 2021, SN10 reached the planned altitude and landed smoothly during the flight test. However, some flames could be seen near the landing, and it exploded a few minutes later.
On March 31, 2021, SN11 reached the planned altitude and returned, but it exploded over the launch site before it reached the ground, and debris fell like raindrops. The investigation concluded that a small methane leak caused an engine fire, partially burned the avionics system, and caused a "hard start" of the engine, which is when there is too much fuel and pressure in the combustion chamber during ignition, ultimately causing the prototype to fail. The machine exploded.
The successive failures caused SpaceX to suspend test launches and improve the design to help the spacecraft land safely - after all, the goal of the Starship development team is to create a reusable transportation system for human interstellar flight. On May 5, 2021, after the structure, control system and engine design were adjusted, the new generation prototype SN15 was launched. It reached an altitude of 10 kilometers above the ground and landed on the designated landing pad when it returned. Although there were still flames burning at the bottom of the starship after landing, they were extinguished by the remote-controlled fire extinguishing system within a few minutes.
