SpaceX is developing a big rocket using stainless steel material. This would be the first time that stainless steel is being worked with for spacecraft development since the efforts made during the Atlas program in the 1950s. The spacecraft that is being developed using stainless steel is the SpaceX Starship.
The carbon fiber that made the body of the Starship rocket and the super heavy booster is to be substituted with 300-series stainless. Elon Musk tweeted a picture of the test version of the Starship on 10th January. It is essentially a prototype that is able of suborbital VTOL (vertical take-off and landing) and achieving a height of 16,400. Elon Musk dubbed them as ‘hops.’
In an interview, Musk told that the design of the Starship and the Super Heavy rocket booster I have been changed to incorporate a unique alloy of stainless steel. He agreed that this sound counterintuitive and that he had trouble convincing his team to go into this direction. However, he was certain that the team was convinced now. According to Musk, the team was pursuing an advanced carbon-fiber structure. However, the process was slow and also cost $136 per kg. Not to mention the 35% scrap rate.
In contrast, stainless steel is much cheaper. Although it is not the easiest and lightest material to work with, looking at the characteristics of the high-quality stainless steel, you wouldn’t be able to tell that its strength is boosted by 50% at cryogenic temperatures. Steel also has a high melting point. In fact, it has a melting point that is higher than that of aluminum. For example, with aluminum or carbon-fiber, you can maybe take it to 300-400 Fahrenheit. However, with steel, you can easily achieve 1500 to 1600 Fahrenheit.
Elon Musk believes that by making use of stainless tell, the schedule for the Starship will be accelerated. The steel is not only easy to work with but also costs $3 per kg as opposed to about $200 per kg of carbon fiber (accounting for the 35% scrap).