Markus didn’t need to calculate Ymir ’s rotation in his head. He didn’t need to know her spin rates about her three axes or the torque needed to counteract them. He didn’t even need to pull up the user interface on his tablet. All he had to do was fly around the shard and look for places where thrusters were staying on continuously. Those were the ones that were overloaded and underpowered. Those were, therefore, the ones where New Caird ’s big engine could be used most effectively.