NASA SLS Rocket design was done by politicians as much as engineers. There is an old saying at NASA, “Failure is not an option”. Unfortunately due to once again having congress design a rocket instead of the engineers at NASA “Failure is an option”. Indeed it may be an inevitable outcome. During its first launch attempts both launch scrubs were due to the use of super cold liquid hydrogen. This is the fuel that the new booster uses. As you might imagine managing a liquid this cold is very difficult to use and manage. So difficult in fact that when NASA was looking at the replacement for the Saturn V, engineers we dead set against using it. The issues in building engines that use it in addition to the difficulties in storing it make this fuel very costly and inefficient. They were overridden by congress and our politicians.