SpaceX should withdraw its application for the Starship as an Artemis lunar lander.

 Copyright 2023 Robert Clark

 In the blog post, "SuperHeavy+Starship have the thermal energy of the Hiroshima bomb. UPDATED". I noted the thermal energy content of both stages is comparable to the explosive force of the Hiroshima bomb, ca. 15 kilotons of TNT. However, it is quite important to keep in mind that NASA uses estimates of the explosive force of a possible rocket explosion that is some fraction of what the total thermal energy might be. Based on this, I estimated the explosive force might actually be in the range of 3.4 to 5.4 kilotons. This is as much as 5 times higher than the explosive force attributed to the famous Soviet N-1 rocket failures at ca. 1.2 kilotons. 

 To get an idea of the enormity of 1.2 kilotons explosive force, and remembering also an SH/ST explosion might be as much as 5 times more powerful, look at the case of the Beirut explosion of 2020. This was not a rocket explosion but of ammonium nitrate but its estimated explosive force was about that of N-1 rocket at ca. 1.1 kilotons.

 

 In the explosion, homes as far away as 10 kilometers were damaged and the terminals at the Beirut airport 10 km away suffered moderate damage with some doors and windows blown out.

 Note now populated areas such as Port Isabel consisting of thousands of residents are within 10 km of the SH/ST launch site, and an explosion of this rocket might be 5 times more powerful than the Beirut explosion.

 In my blog post, I argued that not sufficient attention was being given to the possibility of an explosion by either the FAA or NASA. I wrote to one of NASA's safety offices and was told the safety of commercial launches is not the purview of NASA, but of the FAA. But when NASA is depending on that the commercial rocket to complete the planned flagship space program of NASA they have a responsibility to ensure that rocket is being developed safely as well.

 With the failure of the April 20th test flight of the Superheavy/Starship fortunately now both NASA and the FAA are giving closer scrutiny of the safety of the rocket as it should be.

The Superheavy/Starship actually is the N-1 rocket.

 The explosive force of the N-1 rocket, comparable to that of the devastating Beirut explosion, serves as a cautionary tale for those in the space industry. The comparison has been made of the SpaceX SuperHeavy/Starship approach to the Soviet multiple failed N-1 rocket in that they both wanted to test by actually flying the full rocket until it works, despite the number of failures. 

 This comparison was criticized on the grounds the N-1 engines were not tested individually. Instead, the engineers on the N-1 selected an engine at random from a batch to see if that worked. If it worked the entire batch was chosen. The engines could not be tested individually because the testing was destructive. That engine could not be used if it were first tested.

 The SpaceX Raptor engines on the other hand are tested individually. But here’s the major failing of the Raptor: even if the engine is tested successfully there is still a quite high chance the engine will still fail when used on a flight. That is a major flaw in a rocket engine. No rocket engine would be considered successfully developed with that flaw.

 Because of the numerous failures of the Raptor both on the test stand and in short test hops of the Starship landing methods prior to the April test flight, I estimated the chance of engine failures of the SuperHeavy/Starship test flight was 1 out of 3. SpaceX claimed prior to the April test flight their Raptor 2 was more reliable. The result? Only 1 in 4 of the engines failed. That is still a stunningly high percentage. As a point of comparison it would be like on every flight of the Falcon 9 the expectation would be at least two of the engines would fail during each flight.

 The upshot of this in a very real sense the Super/Starship is just like the failed Soviet N-1 in flying with engines with poor reliability.

 It is my contention the attempt of SpaceX trying to reach a 2025 deadline to have the SH/SS flying and with multiple successful test flights completed puts undue pressure on its normal safety procedures. For that reason my opinion is it should withdraw the Starship for consideration as a lander for the Artemis III lander mission.

   Robert Clark