The third prototype of the Spaceship from SpaceX is now also broken. This time the tank seems to have passed the pressure test. But then it was destroyed when the liquid nitrogen was released. Elon Musk spoke of a possible error in the test configuration, but he still wants to wait for the data evaluation. In the first prototype, the top cover of the tank burst. The weak point in the second prototype was the engine mounting on the lower part of the tank.
Nasaspaceflight.com published a video of the failed test. It shows that the overhead oxygen tank was still covered by frost and was probably filled with it, while the methane tank below was already emptied. Then the tank buckled. The order does not necessarily have to be decisive for the failure. The cause could also have been an accidentally left open valve.
Very thin-walled tanks of rocket stages not only have to be able to withstand a high pressure inside, the pressure is also necessary to stabilize the tank filled with several thousand tons of fuel. A similar principle has already been applied to the older American Atlas missiles and the Centaur upper stage. Like in a well-known video of the collapse of one Atlas Agena rocket in 1963 the starship also lost pressure before the tank collapsed.
The pressure test with liquid nitrogen is intended to simulate the conditions of a tank filled with liquid oxygen and methane at a temperature of -195 degrees Celsius. The day before, the prototype had already been successfully tested at ambient temperature. The second test was delayed by several hours after a few attempts on the test stand caused some valves to leak due to the low temperatures.
The destruction of the third Starship prototype is another setback for the program. However, SpaceX seems to have successfully eliminated the weaknesses in the structure and structure of the millimeter-thin sheet steel tank. The landing legs necessary for the first flight test were already installed at a height of 150 meters in the prototype. Control surfaces and the tip of the nose were dispensed with for this flight program. The program will now only be carried out by the fourth Starship prototype, which was under construction before the test.
The test took place despite measures to contain Covid-19. However, in Texas, where the test took place, the shutdown isn't as strict as in many European countries. While work should generally be moved to the home office, the following applies to so-called essential critical infrastructures and services far-reaching exceptions.