Solids or no, there were a lot of engine-out scenarios that would cause loss of crew. There were substantial parts of the flight where the orbiter wouldn't have the energy to reach a runway.
And the whole dispersed engine system of the Shuttle made any sort of engine out quite dangerous due to imbalanced thrust. When the engines are all right next to each other it's much more resilient against the failure of one, but the Shuttle would be in trouble if it lost any of it's three legs.
And the whole dispersed engine system of the Shuttle made any sort of engine out quite dangerous due to imbalanced thrust. When the engines are all right next to each other it's much more resilient against the failure of one, but the Shuttle would be in trouble if it lost any of it's three legs.