Originally Posted by FordGT90Concept
I think steam turbines are more efficient at generating electricity than steam pistons. It's also substantially lighter. Seems silly to use an inferior, older technology unless they require lots of torque for something.
If you already have rotational motion you could use it to change the pitch, yaw, and roll of a probe without the need of too much additional hardware that way you don't need to use electric motors instead leaving more power for other things.