As I have mentioned before, I am trying to optimize an Earth - Mars low-thrust transfer using a particular method. It has been mentioned to me, and I have seen it in many papers, that thrust history is quite important. I understand that it is important in the sense that the thrust can't be too high for the thruster to actually follow that trajectory - but is there more? Why is thrust history so important? It seems to me that if it were just about keeping the levels within a range you could just include it as a penalty method in the optimiser?
The main reference I am consulting is Conway, B. "Spacecraft Trajectory Optimization"